Dr Carolyn Lam: Welcome to Circulation on the run, your weekly podcast summary and back stage pass to the journal and its editors, and welcome to a whole new podcast format in 2019. Ha-ha, I bet that surprised you. Well guess what? This new format promises more interaction, more discussion and a whole lot more fun, and that's because to begin with, you don't have to listen to me talk to myself half the time anymore. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore, and I am simply delighted that Santa gave me a partner on this podcast, and co-hosted with me, and my gift is none other than Dr Greg Hundley, associate editor from the Pauley Heart Center, at Virginia Commonwealth University Health Sciences. Welcome Greg.
Dr Gregory Hundley: Thank you so much Carolyn. How exciting is it to start this new year with this exciting format, where we'll take several of the key manuscripts from Circulation and discuss them? Picking five each time, and as you've alluded to, we're not going to get rid of that favorite format, where we take a select paper and interview and work with the authors.
Dr Carolyn Lam: Exactly. In fact, maybe I could liken it to welcoming everyone to join us over a cup of coffee, each week, with the journal in the hand and we're just going to discuss it, and never forgetting that feature paper with the authors, and this week's paper is huge. I love it. We're actually going to be talking about blood pressure control in the barber shop. But before then, here's the articles that we've chosen to discuss. So Greg, you got your coffee ready? Shall we start?
Dr Gregory Hundley: Absolutely Carolyn, and let's get going first with Gorav Ailwadi, from University of Virginia, his paper evaluating the utility of MitraClips in those with secondary mitral regurgitation. This is really a follow-up from the EVEREST study. It's not a randomized trial, but it's a longitudinal look over time, at 616 patients. Interestingly, those individuals that had class three or four heart failure, that had the MitraClip, the left ventricular volumes got smaller in a year, the hazard ratio for events became less. The magnitude of mitral regurgitation went from 4+ down to 2+. Exciting findings.
Dr Carolyn Lam: Interesting, but you know Greg, these all sound so positive. Why is it so different in the Mitra FR study?
Dr Gregory Hundley: Absolutely Carolyn. So, as you know, Mitra FR, that was a randomized trial. So, this study doesn't compare, the EVEREST study in this issue, doesn't compare with conventional medical therapy, that's number one, and Mitra FR did. Also, the Mitra FR patients were a little bit sicker. The ejection fraction really was 15 to 40 percent, and in the EVEREST study, much higher, average 45 percent. In fact, many had a normal EF. So it really raises a lot of questions as to whether or not this finding will hold up in future randomized trials, which we'll be looking to see the results.
Dr Carolyn Lam: Indeed, and it was really nicely discussing the accompanying editorial wasn't it, which I really enjoyed. Well, the paper I picked out Greg is from Dr Gatzoulis from The Royal Brompton Hospital, and it's actually the MAESTRO trial. Now, MAESTRO is a randomized control trial of the endothelin receptor antagonist macitentan in patients with Eisenmenger syndrome. Short and long of it, macitentan did not show superiority over placebo on the primary endpoint of change in baseline to week 16 in exercise capacity. And there was also no relevant trends observed for the secondary endpoints.
However, among the exploratory endpoints, macitentan did reduce Nt-proBNP in the main cohort, and improved pulmonary vascular resistant index, and exercise capacity, in a hemodynamic sub-study. Importantly also, there were no specific safety concerns with macitentan.
Dr Gregory Hundley: Sounds really interesting, Carolyn. But how did this compare with prior studies that have really focused on endothelin?
Dr Carolyn Lam: Great question. So, MAESTRO's only the second randomized control trial of an endothelin receptor antagonist in Eisenmenger Syndrome. BREATHE-5 was the first, and this used a different endothelin receptor antagonist that was bosentan, also in Eisenmenger Syndrome, and actually found that bosentan reduced pulmonary vascular resistance as its primary efficacy endpoint, without worsening systemic pulse of symmetry.
So, very different trials in terms of endpoints, as you can hear, but also importantly, different populations that were enrolled. MAESTRO enrolled a more heterogeneous population with more complex forms of Eisenmenger, including patients with Down syndrome, had a broader WHO functional class inclusion, and allowed the use of pre-existing therapies such as PDE5 inhibitors.
Dr Gregory Hundley: That's really spectacular, Carolyn. Very interesting findings for something that these vasoconstrictors, vasodilators, often very harmful. Switching over, I've got sort of another paper that is also working on vasodilation, but comes really from the world of basic science. And it's from Ingrid Fleming from Goethe University in Frankfurt, Germany, examining how does hydrogen sulfide, a common gas that we have in the environment, it smells terrible, we worry about sulfuric acid and acid rain, but how does this promote vasodilation in the system?
And so, in this basic science study, they unlocked sort of a key that this hydrogen sulfide is produced by cystathionine gamma-lyase, CSE. And why is that important, and what does it do? Well, production of H2S by CSE goes and inhibits human antigen R, or HuR, that regulates cellular proliferation and growth. And so, basically these authors have unlocked a mechanism by which hydrogen sulfide can be protective.
So, what's interesting Carolyn is that patients can have elevated levels of L-cysteine, increased expression of CSE, so you've got the components and the manufacturer of H2S, but they still have low arterial levels.
Dr Carolyn Lam: Hm. So, how can this be addressed then? How can we raise that H2S?
Dr Gregory Hundley: That's what's so clever that the investigators found out, Carolyn. They found a slow-release oral active drug, a sulfide donor called sodium polysulthionate, H2R, or sulfhydration, and can inhibit atherosclerosis development or progression when these levels are low.
Dr Carolyn Lam: Indeed. sodium polysulthionate. Awesome, Greg! That is so cool. Honestly I just loved your explanation of that. Okay. Well, I've got another paper to share. And this is from Dr Bress and colleagues from University of Utah School of Medicine. And this one is really interesting because these authors estimated the number of cardiovascular disease events that could be prevented, and the treatment-related serious adverse events that could occur over ten years, if U.S. adults with hypertension were achieving the 2017 ACC/AHA guideline recommended BP goals, compared to their current blood pressure levels, as well as compared to achieving the older 2003 JNC7 goals, or the older 2014 JNC8 goals.
Now, basically they found that achieving and maintaining the 2017 guideline blood pressure goals over ten years could prevent three million cardiovascular disease events, a greater number of events prevented compared to prior guidelines, but this could also lead to 3.3 million more treatment-related serious adverse events.
Dr Gregory Hundley: So, Carolyn, hasn't a main concern of this type of work been that these new guidelines over-extend the reach of our treatment?
Dr Carolyn Lam: That's a real concern that I've also heard. The lower blood pressure thresholds used to define hypertension in the 2017 guidelines could indeed lead to more diagnoses. However, this paper helped because remember that the recommendation for anti-hypertensive drug treatment in patients with the pre-treatment blood pressure of 130-139 systolic, or 80-89 diastolic, was limited to those at high cardiovascular disease risk. So not everyone, but only those at high cardiovascular disease risk.
And so, treatment under the 2017 guidelines, by these data, would lead to more health gains, while only extending treatment to 5.4% more adults with hypertension compared to JNC7. So, this paper really modeled these things out with important contemporary U.S. adult populations using a national representative, a sample of U.S. adults, and NHANES, as well as REGARDS, and they also used estimates of benefit from the recent large meta-analysis of 42 blood pressure-lowering trials.
So, important data that I think are going to be reassuring to a lot of people managing these patients. Well Greg, that really brings us to the end of our little chat. Now, let's move to our future discussion, shall we?
Could cutting blood pressure in a barber shop be the long-term solution to hypertension in African-American men? Well, the future paper of this first issue in 2019 really talks about it. Greg and I are so delighted to have with us the authors of the paper, Dr Ciantel Blyler, and Dr Florian Rader from Cedars-Sinai Medical Center, as well as our associate editor, Dr Wanpen Vongpatanasin.
So, Ciantel, can you just perhaps start by telling us what you found.
Dr Ciantel Blyler: So, what we're talking about today are the 12-month results as a follow-up to our 6-month results that we published earlier this year. So, we took 319 African-American men in Los Angeles County, and randomized them to two groups. One group saw a clinical pharmacist who worked with them to reduce their blood pressure, and the other group just worked with their barber to talk about blood pressure, and encourage usual follow-up.
And, as we saw at the 6-month mark, blood pressure really improved in the group that was able to work with the clinical pharmacist. So, we saw an almost 29 mm Hg drop in the intervention group, as compared to only 7 mm Hg in the control group.
Dr Gregory Hundley: Ciantel, Florian, that is really exciting results. What is a collaborative practice arrangement, and how did you affect that in Los Angeles?
Dr Ciantel Blyler: So, collaborative practice is actually widespread in the United States. California is one particular state that is kind of ahead of the curve with respect to collaborative practice between pharmacists and physicians. But what it essentially allows a pharmacist to do is to prescribe, monitor, and adjust medications underneath a physician's supervision. So, a document is drawn up, medications are selected, and an algorithm so to speak is put together so that a pharmacist can treat a patient independently of a physician needing to be there.
Dr Greg Hundley: Very nice. And did you find in the pharmacist-led group that these patients were taking a different anti-hypertensive regimen, or were they more compliant? What do you think was the reason for the discrepancy in this magnificent blood pressure drop in this group of hypertensive men?
Dr Florian Rader: So clearly, there were a lot of differences between the two groups. First of all, we had a protocol with our favorite blood pressure medications that we use clinically here in the hypertension center at Cedars-Sinai. Essentially it is long-acting calcium channel blocker, specifically Amlodipine, longer-acting angiotensin receptor blockers, or ACE inhibitors, and a third line, usually a thiazide diuretic, and also a longer-acting one, not the usual Hydrochlorothiazide, but specifically Indapamide that we used for this research study.
Dr Greg Hundley: And do you think that there was more compliance in this pharmacist-led group?
Dr Florian Rader: One would expect that. First of all, I think that seeing the clinical pharmacist, more frequently being reminded of taking the medications, having feedback by actually seeing the blood pressure numbers in the barber shop, I think would help. But then, in addition, we choose these medications not only because they affect it, but also because they're easy to take. They're once-a-day medications with very high continuation rates in larger studies, so they're just easier to take than other medications that are oftentimes prescribed.
Dr Greg Hundley: It sounds like also, there might have been a trust factor. Because you're seeing the same person over and over in a very nice environment. Was that a factor?
Dr Ciantel Blyler: Absolutely. I think there's a different level of trust that's established when you meet somebody on their own turf. So I think the fact that we met men in barber shops where they felt comfortable, where many of them had been going to the same barber for over a decade, it made all the difference in terms of establishing a rapport, and gaining their trust with respect to having them take medications. So, I think that was a huge part of why we saw increased adherence, and really sort of a commitment to the program.
Dr Greg Hundley: And we certainly recognize how harmful hypertension is in individuals of Black race. How does this group in Los Angeles translate to perhaps other Black men in the United States? Particularly, for example, in the South.
Dr Ciantel Blyler: I think the program could translate really anywhere. I think what makes it so tailored to African-American men is this notion of going into a barber shop, which is a very important place in the Black community. So, again, sort of going back to what I said earlier, most of these men had been seeing the same barber as frequently as almost every two weeks for over a decade. So, it really helps increase the frequency with which we could interact with the men, and it helped with continued follow-up and adherence to the program.
With respect to the area of the country again, I think it translates.
Dr Carolyn Lam: I've got a follow-up question to that, if you don't mind. So, I'm here listening all the way from Singapore, and I'm just so impressed, and frankly just enamored by this study. And wondering what is the barber shop to my local Chinese guy? I'm actually wondering if it's the kafei dian and that stands for coffee shop, and I'm also wondering what about the women? Wanpen, do you have any insights that you want to share?
Dr Wanpen Vongpatanasin: I believe that even Dr Victor had thought about the beauty shops, that is a barber shop study in parallel, and this could very well work very well. Who knows, we could be going to massage parlor, anywhere, that when we feel relaxed and be ourselves, we go out our way, out of our regular activity, and it could really be a neat idea. And for a study, I'm not sure I could do something out of the box. I would say it must have been successful as this approach, and partly it could be because of the additional pharmacists engage likely. So, I think this is a perfect combination.
Dr Greg Hundley: Wanpen, you had mentioned Ron Victor. Maybe Ciantel, Florian, and Wanpen, you used to work with him. What did Ron mean to this study? Ron Victor unfortunately passed away this past Fall.
Dr Florian Rader: Ron hired me almost seven years ago now straight out of fellowship. He was personally my mentor. He taught me all the tricks when it comes to the work of the management of hypertension, so personally I owe him a lot. Regarding the study, he's been thinking about this for a long time, this approach to hypertension management. He's tried it in Dallas. It worked partially, but not very well because he didn't have a pharmacist, and he didn't have somebody that made it their goal to lower blood pressure no matter what.
And in this study, we had somebody like that, the clinical pharmacist. So, Ron Victor has thought about this for a long time, has done a lot of analysis of the Dallas hypertension study, and figured out why it didn't work out in Dallas, and really cooked up a recipe for this trial, and the results speak for themselves.
Dr Greg Hundley: Wanpen, do you have anything to add about Ron? I think he was your mentor as well.
Dr Wanpen Vongpatanasin: Absolutely. I trained with him actually from the internship until fellowship, and I owe my career to him. And actually, I see this idea stemming from the Dallas heart study when he did the survey, and realized that if you just wait for patients to show up in the clinic, that you're not going to get anywhere, because African Americans have higher blood pressure at a younger age, and are more susceptible for target organ damage. And as we all know, by the time many presented with, they already have end-stage kidney disease or cardiovascular disease by the time first presentation. So, to avoid it, we have to go into much earlier, not wait until they come to the healthcare facility, and I'm glad to see that this idea is really becoming widely successful more than anyone can imagine.
Dr Carolyn Lam: What a beautiful tribute. What a poignant note. Thank you, all of you, for your great input, and for publishing this amazing paper with us at Circulation!
Thank you, listeners, for joining us today on Circulation on the Run with Greg Huntley and me. Thank you, and don't forget to tune in again next week.
This program is copyright American Heart Association 2019.
Dr Amit Khera: Welcome to Circulation on the Run, your weekly summary and backstage pass to the journal. I'm Dr Amit Khera, associate editor and digital strategies editor from UT Southwestern Medical Center in Dallas. And I have the privilege of standing in for Dr Carolyn Lam, your usual weekly podcast host. Today we have a special treat. It is our semiannual fellows and training FIT podcast. And the additional part of this treat is we have three very special FITs today. These are our assistant editors for social media for Circulation. And really I want to introduce you just a moment, but I want to thank these three for their hard work and efforts. It really is them that helped bring our social media to life. And importantly for us, we really have a commitment to enhancing fellow education involving fellows in our editorial process and really making sure that the journal is appealing to fellows in training. So we really rely on these three to help us understand what best resonates and what is most helpful for fellows in training. So without further ado, Jainy Savla from UT Southwestern. Welcome Jainy.
Jainy Savla: Thanks for having me on the podcast today.
Dr Amit Khera: And we have Daniel Ambinder from Johns Hopkins University. Hi Dan.
Daniel Ambinder: Hey Amit. Thanks for having me on the podcast today.
Dr Amit Khera: Absolutely. And finally we have Jeff Hsu from UCLA. Hi Jeff.
Jeff Hsu: Hi Amit and hi everyone. Very glad to be here.
Dr Amit Khera: Well, Jainy, I'm going to start with you. You've been with us on the social media side the longest. I think it's maybe almost a year or a bit more that you've been working on these efforts. And again, very much appreciate all of your hard work and insight. Tell us a bit about yourself.
Jainy Savla: So I'm currently a research fellow at UT Southwestern. So I completed my general cardiology training and I've been doing some extra research training in one of our basic science labs there.
Dr Amit Khera: So not surprisingly with your background, do you select an article? So we've asked them each to select one article as they've been working through the social media side and see all of our articles come through. Each to select one that they found was interesting and perhaps summarize for us what it included and what appealed to them. So Jainy, tell us a little bit about the article you chose and why you chose it.
Jainy Savla: So, I chose one of the articles that was published in April of 2018 from the Molkentin team lab. And this is a basic science article that focused on which types of cells contribute to heart regeneration. They hadn't thought that there was cardiac progenitor cell that could contribute to the development of new cardiomyocytes. And more recent data has shown that maybe that's not quite the case. So what this study did was used a lot of fancy lineage tracing models to try to figure out which types of cells we're actually contributing to the development of new cardiomyocytes. So importantly, what came from this was that one of their models, they were able to delete two transcription factors that are necessary for cardiomyocytes to develop from these progenitor cells. But they found that when they did that, they even got a higher number of cardiomyocytes that formed. And then what they were able to show in this paper was that actually comes from fusion of leukocytes to cardiomyocytes. And then interestingly, they found a role for one of these transcription factors and the development of endothelial cells. So that was kind of a new, not known function of one of these genes that was previously thought to be just contributory to cardiac development.
Dr Amit Khera: It's really a fascinating article when you think about it. Most of the science we publish are people bringing to light new discoveries and certainly there was a component of that here. But in many ways, it was kind of a different article where there had been this a prevailing thought about these c kit positive cells and here they're actually had gone through, refuted what people had thought was happening with these in this de novo cardiomyocyte formation. So you'll see that very often where people's articles or work is headed out to sort of maybe refute or set right what's happening in the literature in the field. Can you comment on that as to that type of article and how that appealed to you in this study?
Jainy Savla: That is interesting because previously it has meant that these cells can be used as a therapeutic option in human patients. But some of them were recent data showed that perhaps the new cardiomyocytes weren't actually coming from these cells, but it was hard to say. So the nice part about this paper was really they used a lot of important lineage tracing models to really show where these cells are coming from. And it helped clarify some of the, I guess, more confusing science that had been in the field since there were a few papers that showed these cells were contributary and then a few papers that have shown that maybe they weren't. So I think that's really helpful, particularly when you're talking about things that could be potentially used as therapeutic agents in human. And also the interesting thing is that while these cells themselves may not be useful to perhaps harvest and give to someone, you could potentially alter these cells and then they produce cells that fuse with cardiomyocytes. Or could you use this a different way? So I thought that was also interesting about this article.
Dr Amit Khera: Great points in it. It does remind us again that in our enthusiasm for rushing things to clinical practices in some things in this field, the importance of rigorous basic science to really understand the molecular underpinnings. And as you mentioned, there's some new insights here that could be used for clinical therapeutic purposes in the future. So definitely an interesting article and glad you enjoyed it and brought it to our attention. I'm going to ask you a bit of a different question. You again have been working with this in the social media side for longer. You've seen this now for some time about the different articles that come through. I know you and I've had several conversations about our different platforms, Twitter or Facebook, and how they're different and how we engage with them and how we engage with the audience. Can you tell us a little bit just reflecting now on your time and working with social media from a journal perspective, kind of what you've learned? What are some interesting observations over this year?
Jainy Savla: Definitely one interesting observation is just that their general usage of these social media platforms has increased significantly since I've started doing this. And you can see this with when we get articles that are accepted, how many authors have Twitter handles that they'd like to be tagged in some of these posts. And that's just gone up significantly since I've started doing this. And that also changes sort of what the comments we get on some of the posts and the back and forth discussions that we're seeing on these platforms. And then the second thing I found really interesting over time is that the way people use Facebook is really different from the way people use Twitter. And you can follow the discussions that people have linked to our posts a little bit better on Facebook. And then on Twitter, there's also a lot of similar discussions about these posts. But they kind of manifest in different ways and it's really interesting to see how that plays out.
Dr Amit Khera: I think those are fantastic points. And from a fellow's perspective, how do you think fellows are engaging with social media now compared to maybe, I don't know, when you started your training a few years back. What have you seen in a positive light?
Jainy Savla: I mean in general, there are more fellows on Twitter now than when I was a first-year fellow. Even myself, I've got my Twitter account when I was in fellowship. I didn't have one prior to that. I mean it's interesting because people are able to showcase their work a little bit better I think with these types of handles whereas before maybe you wouldn't know that even one of your own co fellows had published something. So it's kind of nice to see people use that kind of as a networking tool in some ways or to showcase some of their own work, which is something that when I was a first year and I didn't have a Twitter handle and there weren't as many fellows on Twitter, I didn't really notice some of the work that's being done by some of my colleagues at my level.
Dr Amit Khera: Those are great points and I'll stoplight some of the things you just said talking about it being a way for fellows to really showcase their work, to help with networking and in some ways, it's sort of the great equalizer. So I think it's really a valuable platform specifically for fellows. Well thank you Jainy. I'm going to move on to Daniel and hear a little bit from Daniel. Tell us a bit about yourself.
Daniel Ambinder: I'm currently a second year cardiology fellow at John's Hopkins Hospital and I plan on doing interventional and structural cardiology in the future.
Dr Amit Khera: Great and certainly a lively and growing field and so many exciting things happening. Well, it's interesting you chose an article today that is more of a clinical article and obviously quite different than the last one we heard, but equally as interesting. Tell us a little about the article you've chose and why you chose it.
Daniel Ambinder: I was very excited about this article that was published in Circulation back in July 2018. So, it's by Dr Borlaug and Reddy on how to diagnose HFpEF and what they did was they took patients with clinical dyspnea and they used invasive human dynamics to kind of assess whether or not they had HFpEF. And by doing so they were able to generate a list of clinical and eco based guidance to help us kind of identify patients with heart failure with preserved ejection fraction. So they came up with this amazing little table which was featured in Circulation and on Circulation twitter, where they have a chart that basically goes through several clinical variables including weight and hypertensiveness, atrial fibrillation, pulmonary hypertension, being elderly. And filling pressure is based on echo cardiographic information. And by that they were able to generate a score and give you a probability of if your patient has HFpEF or not.
And the reason why I really enjoyed reading this article and also posting this article was because going through internal medicine and not being so fundamentally aware of echo and kind of what goes into understanding left ventricular filling pressures, it was challenging to make a diagnosis of heart failure with preserved ejection fraction. Do you just basically say, "My patient has lower extremity swelling but normal EF? They have heart failure with preserved ejection fraction and [inaudible 00:09:32] on the [inaudible 00:09:33]. And so I thought that this would be really helpful to the medical community at large. And in fact, shortly after we posted it, I saw that our cardiology console fellow is actually utilizing this exact table to help one of the medicine teams manage a patient with lower extremity swelling and come to the diagnosis of heart failure with preserved ejection fraction. So that is why I chose this article for today.
Dr Amit Khera: That's a great article and I thought you summarized it very well. And it is a field. HFpEF you'd see a lot of articles in Circulation on this topic. We have many people that are interested from an editor’s level but also from a society level. This is a huge problem, but we know very, very little. And I'm sure you know that as well and this was a wonderful tool. Just shows you're sort of the beauty and simplicity. Although if you read it, the message were pretty rigorous and they had a lot of great work that they did to develop it. But I love that the H2 HFpEF, how they basically came up with it h for heavy and the f from fibrillation. So I thought that was incredibly creative and a very simplistic but useful score. So, you said your, tell us about yourself. Have you used the H2 of the HFpEF score yet?
Daniel Ambinder: Absolutely. I use it in clinic on a daily basis. And I actually pull up the Tweet in my office and show the patients why I think that they have heart failure preserved ejection fraction, especially since many of my patients start to get really nervous when you start talking about heart failure. But then they don't understand that they have a normal functioning heart. They can't really put those two together. And so going through this chart and going through the etiology, or at least what we know about heart failure with preserved ejection fraction, turns out to be quite helpful.
Dr Amit Khera: And the basis of this study goes back to hemodynamics. This obviously is a cohort where they had done invasive hemodynamics to essentially diagnosed HFpEF based on pressure. So as you, as someone who's going interventional and structural where we are really seeing kind of the rebirth or refocus on hemodynamics again, tell me a little bit like what you're learning in terms of hemodynamics and how you think that importance in today's practice of cardiovascular medicine.
Daniel Ambinder: One of my passions is spending as much time as I possibly can in the cardiac ICU. And we're fortunate to meet many different patients that come in with very different kinds of cardiogenic shock for other hemodynamic compromise from other types of shock. And I have found it extremely helpful to think about either using a virtual Swan or by actually getting the measurements with a PA catheter to kind of identify where the break in the system is to hopefully provide our patients with the ability to turn them around in a fast manner before they develop metabolic compromise from prolonged hypoperfusion.
Dr Amit Khera: Great summary of how you're using hemodynamics and the training. And I'm going to pivot. The last question for you is when we first met I think several months back and we're communicating about your interest in social media, one thing that was really interesting and fascinating was the great work you're doing on Twitter on your own account where you essentially, if I think you told me this right, you sit on your iPhone and basically in this matter of a very few minutes would construct cases and teaching points on Twitter. So tell me a little bit about that, about using Twitter for medical education and learning cardiology and cases. And I know you're passionate about that. So tell us a little bit more about that.
Daniel Ambinder: Back in May, last year, I had been in my first year of cardiology fellowship. And I was really kind of obsessed with grabbing as much imaging and cases as I could to construct them into teaching stories to share these important stories that I encounter with other people. And so also share the aha moments that I have when I'm learning from my mentors about a new clinical condition or even a clinical condition that I've encountered many times. We never thought about any unique way. And so I was putting these all together and developing somewhat of a library of cases. But I would share them with the residents that I was working with at the time. And then Dr Erin Michos was one of my mentors at Hopkins. She's an echocardiographer and she kind of exposed me to the Twitter community where you're really able to just start reaching out to different people and share the same insights that I had saved on my drive on my computer. And so I started constructing these cases, putting that together and developing them and then associating them with like a few bullet pointed tidbits of pearls that I can put on Twitter. And I quickly realized what an amazing community Twitter have to offer in terms of cardiology and in terms of the medical education community at large.
At first, I realized you can't put out content and not expect to participate in a conversation. It has to be two ways. You have to really engage with others and others will engage with you. And then just a couple months later, it's really grown that you can post a case, post the teaching pearl and in about 24 hours it can be viewed thousands and thousands of times, really internationally. And generates just so much great conversation. So it's been really a tremendous way to communicate with the world, especially within the cardiovascular world.
Dr Amit Khera: Well thanks. I think there's so much learning that can happen and I think the work you're doing with cases and with others. And I know when I've gone on Twitter, even in just two minutes you can see really fascinating things and learn a lot. So keep up the good work and appreciate your efforts there. I'm going to switch gears and finally finished with Jeff Hsu from UCLA. Jeff, tell us a bit about yourself.
Jeff Hsu: I'm a fellow at UCLA. So I actually finished my general cardiology fellowship pretty recently and now I'm a research fellow in the STAR program here. I'm also enrolled in the PhD program at UCLA in the Department of Physiology and planning to defend in the next few months. So right now, very stressed out about that. Starting in July, I'll be starting advanced fellowship in advanced heart failure and transplant here at UCLA.
Well excellent and best of luck to you in your PhD defense. Now you also chose a very interesting article that again, all of yours are a bit different. So tell us a little about the article you chose and why you chose it.
When I chose this article, I was really excited by a few weeks ago. It was published in the December 4th issue of Circulation called Determining the Pathogenicity of a Genomic Variant of Uncertain Significance Using CRISPR/Cas9 and Human Induced Pluripotent Stem Cells. So this came out of the lab of Joe Wu at Stanford and the co first authors is Ning Ma, Joe Zhang and Ilanit Itzhaki. But I think the beauty of this article is that it really addressed this frustrating clinical scenario in question that we often encounter nowadays in this era of genome sequencing. And now that we're sequencing a lot more people, since the cost of sequencing has come down a lot, we were finding a lot of these mutations that we don't know what to do with, so I think Dr Wu's lab really try to address this question using the disease model with the cardiomyopathy. So, leveraging Dr Wu's expertise in using human induced pluripotent stem cells or iPSCs, they found a patient who is actually healthy but apparently had this mutation in this gene called MYL3 or myosin light chain 3. And so this patient had a variance of uncertain significance in this gene.
Now, notably, this patient, again had no clinical phenotype, was very healthy and the patient's family members over three generations were all healthy too. But had this mutation that based on in silico analyses was thought to be likely pathogenic. So using cells from this patient that they reprogrammed into cardiomyocyte, they tested various properties of these cells from the same patient to see whether or not they thought this mutation is actually a pathogenic mutation. So again, using these reprogrammed cardiomyocytes, they tested a variety of things including gene expression, sarcomere structure, and cell contractility, action potentials, and the handling of calcium. And they saw that even with this mutation, there were no abnormal findings in vitro in their system.
Now just to prove that their cell culture system and this in vitro model of testing the pathogenicity of certain mutations actually works, they actually took cells from a patient who did have the clinical phenotype as a result of a known mutation that causes hypertrophic cardiomyopathy. And found that when testing those cells in vitro, they did demonstrate abnormal phenotypes in all the parameters I mentioned before. So I thought this is really exciting. I thought this is a great way to address, potentially answer whether or not we think these variants of uncertain significance that we often encounter are indeed pathogenic because we are often just left in this situation where we don't know what to do with this information. But this potentially at least is a proof of concept for this protocol where we can finally take advantage of the ability to take cells from our patient and actually test them in the lab to see whether or not either various treatments work or whether or not these mutations that actually will results in pathology down the line. So I thought overall this was a great paper that was a great summary of how we can take the bedside to the bench actually. And I'm just really looking forward to the future where we can maybe then bring it back to the bedside.
Dr Amit Khera: Well thanks. I think that's an excellent choice and a great summary. And this article really hit all of the kind of timely and cutting-edge topics in the era genomic medicine and precision medicine have really kind of individualized treatments. And when we get stuck, these VUSes, these are a nightmare. And also this is sort of proof of concept for extending this to other treatments and other ways to test drugs and therapies. I've heard Joe, we talk about this before and use the word disease in the dishes. He did I think in the article itself and it's exactly that. I mean the potential here is profound. I'll pivot this into the next question for you. For our roles, one thing we do is we interact a lot with media and I interact a lot with them to help translate, I guess, the articles that we have to things that would be able to be digestible for media and for lay individuals. It was interesting because it's hard for us to do that with basic science and most of the time we have some difficulty in translating that. But this one translated pretty well and I think we had done some various press releases and things because it really showed the potential of modern medicine and kind of the excitement of it.
But that gets to the question I have for you, something we have discussed as well, your interest in basic science and some of the challenges of taking basic science articles and digesting them down to a couple hundred-word tweet. Even as beautiful as all the pictures are, and in this article I think there's six figures, but each panel is 10 pictures or 10 figures by themselves. And how do we digest basic science articles down to make them really appeal to people on social media and help people understand that may not be in the fields or in basic science that are clinicians, if you will. I know you've thought about that a little bit. Tell me a little bit about your thoughts on that.
Jeff Hsu: Jainy, Dan and I have this challenge on a weekly basis, figuring out how to summarize great articles such as this one into a short tweet. And I think that is a big challenge particularly for basic science articles on social media to make it appeal to a broader audience because the audience you're seeing on Twitter and Facebook, again, they're not just basic scientists. If you want to catch people's attention, you need to find a way to really understand the big picture of the question you're answering in your basic science research. So I think that is a challenge. You're challenged to make your science appealing to a broader audience. But I think again, that's one of the advantages of social media is that you can appeal to a larger audience and have a wide range of people engage with your research and understand your research. So it is something that we work on is to try to pick out the figure that best represents the science that was done in these basic science articles.
It can be quite challenging because a lot of times one picture won't do it justice. So it's tough to distill a full article in one picture. It is helpful when some articles do have a summary, a graphic or figure where they typically reserve their last figure for either a cartoon or some type of schematic that really explains either the mechanism or pathway that they explored in their article. So what we've found is that these articles that do have some of these illustrations or summary figures, they seem to engage a larger audience on Twitter and social media. So personally I find it more appealing when I do see these summary figures. So if there is one recommendation, I would have the basic science researchers, especially trainees is in this age of social media, try to come up with an illustration or summary figure for your research. I think it helps you figure out what is truly important with the research that you've done and helps you communicate this research to a broader audience. And I've seen a lot of people take advantage of a graphic designers to really help them illustrate their research. And I found that to be very effective in articles I've read on social media.
Dr Amit Khera: Thanks Jeff. That's a great point and great suggestion. And certainly these days the most effective communicators are those they can translate their complex science into easily digestible bites and can think of ways to portray them in ways that sort of summarize, like you said, be it summary figures or otherwise. And it's a challenge and also talent. And you all are certainly perfecting that. Well, I think we've had an excellent conversation. I have to tell you, I'm so excited to get the chance to spotlight you all. You do excellent work each day. Every week you're working hard and coming up with great ideas and suggestions and we really value having your input as fellows and training and as a colleague.
Thank you for joining us today on our FIT podcast. Amit Khera standing in for Carolyn Lam. We look forward to seeing you for our next edition of Circulation on the Run. This program is copyright American Heart Association 2018.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
In today's feature discussion, we will be doing a deep dive into the LEADER trial results, looking at new results of liraglutide and its effects in patients with type two diabetes, with or without a history of myocardial infarction or stroke. All of that coming right up after these summaries.
In today's issue, five groups of investigators in two original basic research articles and three research letters tackled the same biological question, and all reached the same conclusion that cells in the heart expressing the SCA-1 cell surface antigen do not become cardiomyocytes to any meaningful degree, and instead become endothelial cells. Among the original basic papers, first author Dr Vagnozzi, corresponding author Dr Molkentin from Howard Hughes Medical Institute and Cincinnati Children's Hospital Medical Center, and their colleagues use the inducible recombinase method and generated a constitutive recombinase at the SCA-1 locus. They found that cardiac resident SCA-1 positive cells were not significant contributors to cardiomyocyte renewal in vivo. Instead, SCA-1 positive cells generated cardiac vasculature throughout development, during aging, and following injury with trivial contribution to the cardiomyocyte population.
In the second paper from co-first authors, Drs Zhang and Sultana, with corresponding author Dr Cai from Indiana University School of Medicine and colleagues, these authors engineered a series of genetically altered mice to identify and track SCA-1 positive cells in the heart, and found that SCA-1 positive cells were purely of the endothelial lineage. Together with three research letters, these five papers add to the growing body of evidence that in adult mammals, our new cardiomyocytes arise from preexisting cardiomyocytes and rarely, if at all, from adult cardiac stem cells.
Could metformin be cardioprotective in patients with type one diabetes? Co-first authors Drs Bjornstad and Schafer, corresponding author Dr Nadeau from University of Colorado School of Medicine, and their colleagues hypothesized that adolescents with type one diabetes have impaired vascular function, and that metformin may improve insulin resistance and vascular dysfunction.
To test this hypothesis, they studied 48 adolescents with type one diabetes and 24 non-diabetic controls using MRI of the ascending and descending aorta, as well as assessment of carotid intima-medial thickness by ultrasound, brachial distance ability by DynaPulse, fat and lean mass by DXA, fasting labs following overnight glycemic control, and insulin sensitivity by hyperinsulinemic euglycemic clamp. The adolescents with type one diabetes were randomized one as to one to three months of 2000 milligrams metformin or placebo daily, after which the baseline measures were repeated.
The authors detected early signs of cardiovascular disease with MRI in these adolescents with type one diabetes compared to controls. They further found that three months of metformin therapy improved insulin sensitivity as assessed by gold standard hyperinsulinemic euglycemic clamp, both in normal weight and obese adolescents with type one diabetes. Moreover, metformin improved carotid intima-medial thickness and aortic wall shear stress and stiffness. Thus, metformin may hold promise as a cardioprotective intervention in type one diabetes.
What are the clinical genetic and environmental determinants of varicose vein formation? Co-first authors Drs Fukaya and Flores, corresponding author Dr Leeper from Stanford University, and colleagues applied machine learning to agnostically search for risk factors of varicose veins in nearly half a million individuals in the UK bio bank. They found that greater height appeared as a novel predictor of varicose vein disease in machine learning analyses, and was independently associated in multi-variable adjusted Cox regression. Using Mendelian randomization, they demonstrated that greater height had a causal role in varicose vein development. A genome-wide association study identified 30 new genome-wide significant loci, identifying pathways involved in vascular development, and skeletal/limb biology, and discovering a strong genetic correlation between varicose veins and deep vein thrombosis. The knowledge greatly expands our understanding of disease pathophysiology, and may help future improvements in the management of varicose veins and their associated complications.
The final original paper describes the effect of glucagon-like peptide-1 receptor agonist liraglutide on cardiovascular events, and all-cause mortality in patients with type two diabetes and chronic kidney disease. First and corresponding author Dr Mann from Friedrich Alexander University of Erlangen in Germany and their colleagues performed a post hoc analysis of the LEADER trial comparing the liraglutide's treatment effects in patients with and without kidney disease.
As a reminder, LEADER was designed to recruit a subgroup of at least 660 patients with an estimated glomerular filtration rate, or eGFR, less than 60, approximately 220 patients with severe renal impairment, eGFR less than 30, and at least 440 patients with moderate renal impairment with an eGFR of 30 to 60. The authors found that the liraglutide reduced the risk of major adverse cardiovascular events, and all-cause mortality compared with placebo in patients with chronic kidney disease defined as an eGFR less than 60, and also in patients with albuminuria defined as a urinary albumin to creatinine ratio above 30.
The overall risk of adverse events did not differ between the liraglutide and placebo treated patients either with or without chronic kidney disease in the LEADER trial. In summary, these results show that liraglutide added to standard of care reduced the risk of major cardiovascular events and all-cause mortality in patients with type two diabetes and chronic kidney disease. Furthermore, these results appear to apply across the chronic kidney disease spectrum that was enrolled.
And that brings us to the end of our summaries. Now for this week's feature discussion.
Cardiovascular outcome trials have transformed the world of treating patients with diabetes. And for our feature discussion today, we're going to be talking about a new analysis from a very important trial, the LEADER trial of GLP-1 receptor agonists, and that's the liraglutide. I'm very proud to have the corresponding author of this paper with us, Dr Subodh Verma, and he's from St Michael's Hospital and University of Toronto, and our senior associate editor, Dr Gabriel Steg, from University of Paris. Actually, Gabriel, I'm actually going to start with you for once because I recall perhaps something you may have written about cardiovascular outcome trials.
Dr Gabriel Steg: Yeah, it's really funny. I'll try to take it graciously. You know, I wrote a frame of reference in Circulation a few years ago, wondering whether we were doing good by doing all these large outcome trials for safety with new anti-diabetic drugs, because there had been not one but two, three, four, five, six trials that were essentially neutral, enrolling more than 107 patients and participants at the expense of millions of dollars, and not much came out of it. And this was published in circulation. I was very happy until the next trial comes up, and this is EMPA-REG. And the next one is LEADER. And we have two trials that literally transform our vision of anti-diabetic agents as major agents for cardiovascular prevention. The trial we're going to discuss today, which you wrote about, is one of these trials. And I think I have to revisit my own writings and probably eat my hat.
Dr Carolyn Lam: So indeed, that's a great segue. Thank you, Gabriel. And Subodh, tell us then, what did you look at this time in LEADER? And maybe start by saying a little bit about LEADER, and the rationale for doing this particular sub analysis.
Dr Subodh Verma: Right. So, as Dr Steg mentioned, these were FDA-mandated studies to look at safety and potential efficacy of newer antihyperglycemic agents. The entire premise was that cardiologists and cardiovascular specialists were not really getting that excited about antihyperglycemic therapies in people with diabetes, because there was no data that they did much. And as Dr Steg mentioned, even the data leading up to some of these trials were disappointing, suggesting that they're safe, but they neither reduce nor increase events.
So, I think EMPA-REG and LEADER really changed the calculus in many ways of how we look at cardiovascular risk reduction with antihyperglycemic agents. LEADER was a trial that was 9,340 patients. These are patients that were at high cardiovascular risk, but unlike EMPA-REG that only enrolled people with prior to ischemic cardiovascular events ICAD, PAD, and CVD, LEADER took a position of enriching the population with this spectrum of patients with cardiovascular disease and risk factors.
So, some were in so-called high risk primary prevention who had not had established ASCVD, but had multiple risk factors such as uncontrolled hypertension or chronic kidney disease. Some had evidence of ASCVD, but had not had a prior myocardial infarction. And some, in fact, had had a prior MI stroke or PAD. So, it was a broad population of patients that was enrolled. And the primary result, again, for the primary outcome of MACE, demonstrated a significant reduction in favor of liraglutide versus placebo. And then for the individual components of that primary outcome, they were all statistically significant, or at least went in the right direction. Importantly, CV death was reduced by 22% with liraglutide versus placebo.
I would like to emphasize that in this day and age, and Dr Steg has nicely set the stage, we have started thinking about how do we think about cardiovascular phenotypes of patients. You know, is a drug more likely to reduce heart failure? More likely to reduce ischemic events? And with LEADER, we found that in fact the trial actually reduced mostly ischemic events, and was really not that beneficial on heart failure related outcomes.
So, that was the broad positive outcome from LEADER. They've led to guideline changes worldwide that patients with diabetes should be prioritized to receive an agent that has shown benefit, particularly if they have cardiovascular disease. And one of those agents was empagliflozin. The other was liraglutide. But, secondary prevention is a pretty crowded space, and not everybody can get everything, and not everybody should get everything, and not everybody can afford everything. So, I think leaders like the two of you here are often thinking about, how do you risk-stratify these populations, and how do we start thinking about people who are at greater risk, people who can actually derive benefit? And I think that's the smart and thoughtful way of doing this. And is there a certain threshold at which point the therapy loses its ability to reduce cardiovascular events, at least in the short term?
So, in that theme, in that vein, what we looked at here was an analysis of people in LEADER who truly had a prior ischemic event. And the work that Dr Steg and others have done in REACH registries, etc. clearly establish that that's a population of patients, type two diabetes and a prior ischemic event. You don't really need many more calculators beyond that. That's the highest risk population. And then, the next level is really type two diabetes with a ASCVD. And we know that from REACH as well, that that's the next level of risk. And then, what about people who have type two diabetes just by itself? Which certainly are much higher risk than people who don't have diabetes, but we didn't have a non-diabetic group to compare to.
And what we find is that the higher the baseline risk defined by this, the greater is the absolute risk reduction. The P value is consistent for ... You know, this is non-significant for heterogeneity. but specifically, people with a prior ischemic event derive benefit. People without a prior ischemic event who've had ASCVD derive significant benefit. But, in fact, we found that the curves were almost superimposable for people who did not have prior ASCVD. And that's not to say the GLP-1 receptor agonists should not be used in diabetes in the absence of cardiovascular disease, because they're great glucose lowering agents. They cause hypoglycemia, they cause weight loss. And potentially, within longer exposure times, cardiovascular benefit may actually emerge. And we've heard data from Dr Gerstein's study called Rewind that is positive, that will be presented next year. Harmony Outcomes was a study that was presented recently that also showed a benefit. So, whether in the primary prevention group we see a benefit in the future remains to be seen.
Dr Carolyn Lam: Oh, that's a great, great summary. But Subodh, you know, it's become a bit of what do we define as a primary and secondary prevention anymore, you know? And the patient that already got type two diabetes. Now, in this paper, it's very nice. As you said, has a history of myocardial infarction and stroke. And maybe I could just clarify to the audience, you couldn't just pick up the primary paper and see that because the way the inclusion exclusion criteria were designed in LEADER, you can't just pick up the sub-groups. So, this specific analysis, so carefully and wonderfully done, was absolutely needed. But then you know, what do you think? What's primary and what's secondary prevention anymore?
Dr Gabriel Steg: Well, I want to commend the authors for doing the careful stratification of diabetic patients they've done in the paper, and particularly for pointing out that it's one thing to have had an event where you actually ruptured a plaque and had a traumatic event. And it's very different from merely having plaque in one of your carotids or your arteries, and which is, of course, in turn very different from the majority of diabetic patients who have neither an event, nor diagnosed plaque or established plaque. And when we think about preventing cardiovascular and diabetes, we have to remember that the outer circle, the broader circle of diabetic patients who haven't had disease is the largest component.
Dr Subodh Verma: True.
Dr Gabriel Steg: And these are the patients whom we treat every day with the hope of eventually keeping them from harm, safe from harm, or with therapies that are new and potentially beneficial. And I think your research very clearly shows that there's a gradient of benefit. The sicker the patient, the greater the benefit in preventing MACE. And as long as you get to more healthier phenotypes of diabetes, then there is less of a benefit. Which doesn't mean that we shouldn't use these agents. As you point out, they're very convenient and effective agents for glucose control. But then, their cardiovascular benefits are more uncertain. And I think this is the key message from this analysis, and it's a great analysis.
Dr Subodh Verma: Thank you. I appreciate that. I totally agree that for the doctor in the trenches, particularly the cardiologist who's just trying to get their feet wet with antihyperglycemic therapy, you know? Cardiologists will embrace PCSK9 inhibitors and rivaroxaban at low dose, and maybe a new way of doing surgery or putting an LVAD. But it's very hard to get their attention when it comes to antihyperglycemic therapy. So, defining for them the population that matters the most, where the greatest risk and risk reduction can be achieved, I think is quite important from a clinical standpoint. And I think most cardiologists will agree that type two diabetes and a prior ischemic event is a high-risk population. Type two diabetes in a prior ASCVD is a high-risk population, and the magnitude of CV death reduction here is something meaningful for them to pay attention to.
Dr Carolyn Lam: Yeah, indeed. That's what I love best about this paper. It's actually asking the question the way a cardiologist would, exactly like you had both put. So, what do you think is the next step now? Do you think we need to look at this primary prevention type two diabetics with no established cardiovascular disease? Do we really need to? Is it that we need a method analysis, which you can talk about? Or, is it that we need longer follow up? Or, what next?
Dr Subodh Verma: I think that first of all, we have to get rid of the terminology, and maybe as a heart surgeon, I can be a little bit provocative and just say it. I wrote an editorial to the Declare Study that was just published yesterday in The Lancet called "Pumps, Pipes, and Filter: Do SGLT2 inhibitors cover it all?" Then I made a strong statement there that this nomenclature of primary and secondary really is artificial because it only captures ischemic risk, and does not capture risk of heart failure or renal disease. So, in a patient, as you've asked, Carolyn, who has type two diabetes, whose renal function is 54 or GFR is 55, who's not had a prior MI ... Is that patient primary prevention? Maybe from an ischemic standpoint, but he's clearly secondary prevention from a renal standpoint.
Dr Subodh Verma: So, I think we need to just think about all disease as a spectrum, and not as an artificial cutoff that, if you've had an ischemic event, suddenly the world changes for you there. Because, that gradient I think is probably what we need to somehow appreciate as to where that risk lies. The patient who's 40 who's had no risk factors, you know? The Rashami paper from the New England Journal that looks at risk factor control and diabetes make a very compelling story that if you control your five risk factors, you actually don't have an excess risk of cardiovascular events in diabetes, at least from MACE. The story is whether anybody can have those five risk factors controlled. But, early on in diabetes, with diabetes duration not being that significant, with risk factors not being that significant, I think maybe that's not the population to go after. But certainly, waiting for ASCVD to develop and then start therapy is also not the right way of doing it, so ...
Dr Carolyn Lam: Interesting. I really wonder what new guidelines are gonna show. Gabriel, any other perspective?
Dr Gabriel Steg: Well, first of all, I love the editorial. I thought the title was fantastic, and you summarize here what we need to think about when we think about diabetes; not solely the pipes. As an interventional cardiologist, I'm very interested in the pipes.
Dr Subodh Verma: Me, too.
Dr Gabriel Steg: Not solely the pump, but also the filter. And there's more than the heart and vessels in the complications of diabetes. So I thought it was a great, great title. My view is that we still need to remember that if we take the lifetime perspective, a healthy youngster with type one diabetes, a relatively healthy patient in his fifties with type two diabetes, their probability of dying from cardiovascular disease is enormous. Even though risk calculators will give them a relatively low probability over the 5 year or 10 year term, eventually that's what's gonna get them. And therefore, we still have progress to make. We are fortunate to have lived an incredible period in the past few years where we've had emergence of new risk preventive therapies in diabetes. That's incredible. It's an epiphany. But, it's not over. We need more information, more trials in other populations. We need to look at renal function and heart failure. So, it's a great time to be doing clinical trials in diabetes.
Dr Subodh Verma: Right.
Dr Carolyn Lam: And indeed, a great time to be publishing in circulation. We've been really doing a lot of publications in the cardiovascular outcome trials in diabetes here.
Dr Subodh Verma: And it's being noticed. There's no doubt about it.
Dr Carolyn Lam: I hope so. And, maybe a time for a new frame of reference, because what you just said was diametrically sort of in contrast.
Dr Subodh Verma: I would emphasize one more point, and that is, you know in atherosclerosis, the dominant mechanism has been LDL, right? And Dr Steg here is changing the landscape of that with Odyssey Outcomes and many other strategies. But again, in Circulation, Dr Bhatt, and I, along with the LEADER investigators, recently presented and published a paper showing that liraglutide's benefit is seen independent of LDL cholesterol, and all the way down to people with LDLs of below .5. So, the point is that this mechanism of benefit of GLP-1 seems to be complimentary to LDL lowering. And therefore, I think it offers great hope that you can actually reduce the ischemic burden in diabetes, not just by ultra-low LDL, but by potentially additional mechanisms as well.
Dr Carolyn Lam: Absolutely. And then now, because I have to have the last word here on this show, let's not forget heart failure outcomes in diabetes. I think it's underestimated. I think it's really important. Okay, and with that, thank you gentlemen for joining me today.
You've been listening to Circulation on the Run. Don't forget to tune in again next week.
This program is copyright American Heart Association, 2018.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. What are the long-term effects of oxygen therapy in patients with suspected acute myocardial infarction? Well, to find out, stay tuned for our discussion of our feature paper this week, coming right up after these summaries.
The first two original papers demonstrate that, similar to neonatal mice, one day old and two-day old neonatal pigs are capable of mounting a cardiac regenerative response following myocardial infarction, which is characterized by restoration of contractile function, cardiomyocyte replenishment, and minimal fibrosis. Now, interestingly, this regenerative capacity is lost after the first two days of life.
The first paper is from co-corresponding authors, Drs Yeh and Cook from National Heart Research Institute of Singapore and National Heart Center, Singapore, and the second from co-corresponding, authors Drs Zhang and Zhu from the University of Alabama at Birmingham.
These authors report collectively that proliferation of preexisting cardiomyocytes appear to be the primary source of cardiomyocyte replenishment in neonatal pigs with markers of cardiomyocyte mitosis, sarcomere disassembly, and cytokinesis elevated following injury in the one day and two-day old hearts, but not at later time points.
Furthermore, cardiomyocyte DNA synthesis was increased following neonatal pig myocardial infarction. Cardiomyocyte proliferation significantly decreased after this two-day window, which was associated with a marked reduction in telomerase activity.
Heart failure with preserved ejection fraction may look different in the young compared to that in the elderly. First author, Dr Jasper Tromp, corresponding author, myself, Carolyn Lam from the National Heart Center, Singapore and Duke National University of Singapore, and our colleagues from the Asian Heart Failure Registry studied more than 1,200 patients with HEF PEF from 11 Asian regions and found that 37% of our Asian HEF PEF population was under 65 years of age. Younger age was associated with male preponderance, a higher prevalence of obesity, and less renal impairment, atrial fibrillation, and hypertension. Left ventricular filling pressures and the prevalence of left ventricular hypertrophy was similar in the very young of less than 55 years and elderly HEF PEF of more than 75 years of age.
Compared to age matched controls from the community without heart failure, the very young HEF PEF patients had a three-fold higher death rate and twice the prevalence of left ventricular hypertrophy. Thus, young and very young patients with HEF PEF display similar adverse cardiac remodeling as their older counterparts, but very poor outcomes compared to controls without heart failure.
Obesity may be a major driver of HEF PEF in a high proportion of HEF PEF in the young and very young.
How important is hospitalization for heart failure as a complication of diabetes? In the next paper from first and corresponding author, Dr McAllister from University of Glasgow, the authors examined the incidents and case fatality of heart failure hospitalizations in the entire population age 30 years and older resident in Scotland during 2004 to 2013.
Over the 10-year period of study, among 3.25 million people, the coot incidence rates of heart failure hospitalization were 2.4 per thousand-person years for those without diabetes, 12.4 for those with type two diabetes, and 5.6 for those with type one diabetes. Heart failure incidents had fallen over time for people with and without diabetes, but remained around two times higher in people with diabetes than those without diabetes. Heart failure case fatality was higher in people with type one diabetes. Duration of diabetes and glycated hemoglobin was associated with increased risk of heart failure in type one and type two diabetes. Thus, clinicians should be aware of the importance of heart failure and diabetes, especially in type one diabetes where this is under appreciated.
What are epigenetic mechanisms contributing to ischemia reperfusion injury? Co-first authors Dr Yu, Yang, and Zhang, co-corresponding authors, Dr Xu from Nanjing Medical University, Dr Sun from Fudan University, and Dr Ge from Fudan University, and their colleagues evaluated the potential role of megakaryocytic leukemia one, or MKL 1, as a bridge linking epigenetic activation of NAD pH oxidases, or NOX, to reactive oxygen species production and cardiac ischemia reperfusion injury in mice. They found that genetic deletion of pharmaceutical inhibition of MKL 1 attenuated cardiac ischemia reperfusion injury in mice. MKL 1 levels were elevated in macrophages, but not in cardiomyocytes in vivo, following cardiac ischemia reperfusion injury.
MKL 1 recruited the histone acetyltransferase, MOF, to activate NOX transcription in macrophages. Pharmaceutical inhibition of MOF attenuated cardiac ischemia reperfusion injury in mice, and pharmaceutical inhibition of NOX one or four attenuated cardiac ischemia reperfusion injury as well.
These findings provide a novel link between MKL 1-mediated epigenetic regulation of gene expression in macrophages and ischemic heart disease. This opens the door to small molecule compounds targeting the MKL 1 MOF NOX access as a novel therapeutic strategy against ischemic heart disease.
Is the time from last hospitalization for heart failure to placement of a primary prevention ICD associated with patient outcomes? First and corresponding author Dr Ambrosy from the Permanente Medical Group in San Francisco performed a post hoc analysis of Medicare beneficiaries enrolled in the national Cardiovascular Data Registries implantable cardioverter defibrillator, or ICD registry, all with a known diagnosis of heart failure and an ejection fraction of less than 35%, undergoing a new ICD placement for primary prevention.
They found that older patients, currently or recently hospitalized for heart failure, undergoing initial ICD placement for primary prevention, experienced a higher rate of periprocedural complications and were at increased risk of death compared to those receiving an ICD without recent heart failure hospitalization. Additional prospective real world pragmatic comparative effectiveness studies should be conducted to define the optimal timing of ICD placement.
The final original paper presents result of the VERDICT trial, a large scale randomized controlled trial evaluating the value of very early invasive strategy conducted within 12 hours of diagnosis on long term clinical outcomes in patients with non-SD elevation acute coronary syndrome. First and corresponding author Dr Kofoed from University of Copenhagen and colleagues studied 2,147 patients who were randomized and found that an invasive strategy performed within 4.7 hours after diagnosis was not associated with improved outcomes, compared to an invasive strategy conducted within two to three days.
However, in the pre-specified subgroup of patients with a GRACE risk score of more than 140, a very early invasive treatment strategy did appear to improve outcomes, compared to a standard invasive treatment strategy. And that wraps it up for our summaries. Now, for our feature discussion.
For our feature discussion today, we are talking about oxygen therapy for patients with suspected acute myocardial infarction. Something that seems so benign, something we've taken for granted, and yet now we now question since the Detox AMI trial. Well, for today's feature paper, we have a follow-up of this trial, and I'm so pleased to have actually our associate editor, but also author of this paper, Dr Stefan James from Uppsala Clinical Research Center, and the guest editor for this paper, Dr David Morrow, who's from Brigham Women's Hospital and Harvard Medical School. So, thank you both for being here.
Stefan, could I just ask you to start by taking us back. How was Detox AMI first conceived? What made you even question oxygen therapy? And then, perhaps then, tell us about what this new paper adds.
Dr Stefan James: I think that's so interesting because I think we all learned in medical school that for myocardial infarction, you should always deliver oxygen. That's sort of the first choice. And the other sort of first choice that we learned was morphine. Some of the other important things that we learned was to give not only oxygen but morphine, and nitroglycerin, and perhaps aspirin. And by those four, only aspirin is really the agent that has been proven beneficial to patients.
But we thought for many years actually about this oxygen hypothesis, or we were interested in trying to understand, is it really helpful to give patients oxygen? Or are we in fact harming patients? Because there is, as you may know, there is a metanalysis performed long ago with small trials on the fibrinolysis era that showed actually a threefold increased risk of dying in those patients who had received oxygen in randomized various small trials, and their animal experience actually suggesting that oxygen is also hazardous. You don't think about that so often, but it's really an agent that constricts arteries, and so as the arteries close by a clot in myocardial infarction, there is no way the oxygen that you breathe in your nose can reach the suffering myocardium. It actually contracts the arteries, and may make the infarct larger than it would be otherwise.
Dr Carolyn Lam: I love that explanation. Alright, so what did you find in the current analysis of longer term results?
Dr Stefan James: So, we performed this, the main oxygen trial that we call Detox. We built it upon our national registries, and so we decided to include not only MI patients, but patients who were suspected of MI, in order to be able to enroll patients before the diagnosis was clear. We didn't want to wait for troponins, so we enrolled patients in the ambulances, in the emergency departments, in the cath labs, or in the wards, patients who had suspected myocardial infarction.
Most of them, eventually, did have myocardial infarction, but a proportion did not have myocardial infarction. They had other diseases that resembles MI and have breathing problems. And we selected the cut point of 90%. We said if they are below 90%, they're hypoxic, and it would be unethical to withdraw oxygen, if you were hypoxic. So, we sort of arbitrarily selected the cut point of 90%. And then, we randomized patients to receive oxygen or do not receive oxygen.
We considered to do double blind, but in order to do a double blind, you need to provide air on a mask. And air is not available in ambulances or in the emergency department. We cannot put a mask without anything in it because then it will feel more difficult to breathe. So, we had actually oxygen versus nothing, and we enrolled all patients coming to the cath labs, and emergency departments, and ambulances in Sweden. And thanks to the infrastructure that we have built on the national registries, we were able to enroll these to conduct this large trial, larger than any other trial, 6,600 patients.
In the main study, we found no benefit, and fortunately, no harm of providing oxygen for our primary end point, which was all caused death. But we realized that we were little bit underpowered actually to really clearly rule out that there was any benefit on the primary endpoints. And so, we said, we probably need a longer follow-up, and we probably also need other important measures such as heart failure. Because we thought that oxygen may, if it works, it may reduce the infarct size and may result in a lower risk of heart failure in the long-term. We don't believe that we will reduce the risk of re-MI because we're not interfering with atherosclerosis or plaque ruptures, but we may interfere with the development of heart failure.
So, in this particular paper, we said, longer follow up in order for patients to possibly develop heart failure and increase their risk of heart failure hospitalizations. So, in this paper, we used as a primary endpoint of this analysis, death or hospitalization for heart failure, post MI. And with this way of calculating events, we are more sure that we are not underpowered for this evaluation.
Dr Carolyn Lam: Right. And the results?
Dr Stefan James: The results were completely neutral. There was no benefit at all in any sub group. It doesn't matter if you were ST elevation MI, or no ST elevation MI, or no MI, or high risk prior MI, prior heart failure, respiratory disease, there is no benefits and no harm, which is good. And those results are supported by our findings on troponin levels. So, we checked troponins repeatedly. I shouldn't say top troponin, but the highest measured, we did not find any difference between the two groups in Troponin elevations. And we did not find any difference in LVEF and in Echo performed during the initial hospitalization.
So, I think both of those results support the primary endpoint of death and repeat hospitalization for heart failure.
Dr Carolyn Lam: So David, you've thought a lot about this, and also framed it so nicely when we were just talking a little bit earlier. What do you think is the real significance of this paper on so many levels?
Dr David Morrow: Yeah, I think there are many levels. I think it's such important work because it takes something that we are still doing in many hospitals every day for patients and is difficult to study because it's become part of standard of care, as Dr James pointed out, and so the authors are to be congratulated for being able to study this intervention. And I think in additionally because it is a therapy that's not associated with high cost, has been part of our care for so long, it's not one where there is the support for a large type of randomized trials. So, the ability to perform this with relatively low costs by nesting it in a registry is important, not only for this particular test, but also as a model for future research of so many interventions that we make right now where they started in a time where our threshold for a need for data was much less.
Dr Carolyn Lam: Yeah. Indeed. That's wonderfully put. I am also really struck. It's the importance of the message, but also especially about how you do a pragmatic registry-based randomized trial. The ability of Sweden to do this, it's just rock the world, right? Because we really need solutions like that for our clinical trial world, which has to be sustainable somehow. Could you maybe take us behind the scenes a little bit? I mean you did already in your description. I didn't realize there were so many considerations when you're planning this, but how easy or difficult is it to do a trial like this?
Dr Stefan James: We call the entity RRCT. We call it registry based randomized trial, but being aware that there is no strict definition of what is a registry based randomized trial. So, sometimes for some simple interventions like strategies, we can use only the registry for collection of baseline variables, procedure variables, and also outcomes. The registry can really do everything. The only thing we need to add is a randomization, so then we just program into the registry, which is used live in front of the patients.
So, when I enter a patient in the registry, the personal identification number collects me to the population registry that supports directly back to me name and gender of the patient, and then I enter all the baseline characteristics anyway in the registry. And then, there is a question that comes up that screens my patients. So, the system proposes to me to randomize patients who are eligible because I programmed the inclusion/exclusion criteria. So, it proposes to every doctor in the country, this is a patient that is eligible potentially for this trial and just click randomize, and that's the trial. Everything is completed by that. No extra tests, no visits, no follow up, no telephone calls.
That's the basic, very simple format that can only be used for a strategy, like a device or a strategy. But many of the questions we have in medicine are really regarding strategies. How long should you treat? How often do you need to come back? Sort of strategies. Then, when we've tried to expand this to pharmaceutical agents, and oxygen was the first pharmaceutical agent that we wanted to try. You may not consider oxygen as a pharmaceutical agent, but it is in fact. But it's not manufactured by any companies, and we are still, in this trial, wanted to keep all-cause mortality as the primary end point because that's very reliable. That's indisputable, and in our country it's absolutely 100% correct. If they registered dead, they are dead. There's no question.
The next level we did in the validate was a true pharmaceutical agent manufactured by a company, [byobatterin seprin 00:18:31]. A little bit more complex because you need to be careful about making sure that the patients are receiving the pharmaceutical agent in the right manner, in the right time point. We need to be a little bit careful about collection of side effects, and complications, and so on, but it also worked very well in that trial. If they validated, we did actually adjudicate events because in the primary end point we had it where it was more complex primary endpoint, including myocardial infarction. If you include myocardial infarction or bleeding events, that needs to be defined in a certain way according to protocol. You need to adjudicate. If you really need to rely on the outcome assessment.
We're not trying to take this type of study to the next level, to use it for typical oral pharmaceutical agents. Our largest trial now running is the spirit HFPF lactone versus no treatment in patients with HFPF. And again, this is a pharmaceutical agent that is a very inexpensive. There's no company that would sponsor such a trial, but we think it's a really important question. There's so many patients that suffer from HFPF, and in order to do that trial, it has to be simple and inexpensive.
So, that's running. We hope to be successful. There are, of course, many challenges. Like any other trial, it's difficult to write a protocol. You have to be very dedicated and detailed for any trial. So backstage, this is not easier than any other trial, but for the investigator, it is much easier. That's the reason we have succeeded to reach out to every hospital in the country, and every physician seeing these patients are investigators. And many of them have never done any trials before. They have no experience with research, but still they should be able to randomize and do the trials because it seems to be so easy for them and for the patients. That's the whole idea.
Dr Carolyn Lam: Yeah. I'm just enamored by the whole concept, and of course, a lot of people I think are wishing that we could institute that in all countries as well. Trust me, a lot of conversation has occurred about that in Singapore, for example, where population based capture is possible. But, as you said, it's not that easy. It's got to be well thought out. Protocols still have to well thought out. Investigators still need to be trained, and so on.
Dr Stefan James: We want the investigators to feel that it's easy, that it's attractive to participate. Not for money, just because it's so easy and so interesting to be part of such an experiment.
Dr David Morrow: I think testing some of those therapies that are commonplace that they're used to, and our nature of practice is this is the perfect type of setting than more complicated interventions where you may need to train the investigators more in order how to implement to them, and apply the therapy correctly. That's the new trend, is ... I think the key issue is that in order to reliably test things where mortality is not the acceptable outcome that you could power adequately for, it's really the endpoint collection in the safety collection, and because of the robust medical record systems you have, you're able to do that. And we're so far from being able to do that reliably in the United States right now that it's not possible to do that. Unless we have specific well-constructed registries, which we do in some areas. I think we're learning, and hopefully we'll get there, but we're far behind [crosstalk 00:21:55].
Dr Stefan James: [crosstalk 00:21:55] Yeah, but even-
Dr David Morrow: [crosstalk 00:21:57] Nationals-
Dr Stefan James: Even if you're not able to do a registry based, I think we all should consider in all trials to do it as easy as possible and really try to ask ourselves, what is the most important reason we're doing this trial? Sometimes we need to collect a lot of extra information because we need to understand the mechanisms or the side effects. If that's the case, I don't think at this trial methodology is not suitable. You shouldn't perform it that way. It needs to be the more traditional, more conservative, more expensive and burdensome way, but for many therapies, a more simple approach, more pragmatic approach is preferable.
Dr Carolyn Lam: Well, thanks again for diving into that because it gives us a real, to me at least, even greater appreciation for this paper when you understand the amount of work that's gone into it. But may I just end by saying, what do you think is the take home message for clinicians now? David, for example, you started by saying everyone's still doing it? I fully agree.
Dr David Morrow: Yeah. I think it's a very simple message, and that we know that oxygen is not effective in patients who have an oxygen saturation above 90%. And there's really no rationale to use it.
Dr Carolyn Lam: Perfect. Has this been put in practice in Sweden already?
Dr Stefan James: It has been. One of the virtues of running these registries is that we can also check the adherence to the results, so we can check that this is not used anymore.
Dr David Morrow: And since the investigators are your entire country, they all learned actually from participation in these trials.
Dr Stefan James: Exactly. Exactly.
Dr David Morrow: There's more of an investment in it already.
Dr Carolyn Lam: That's amazing. So, thank you again for sharing. Thank you for publishing this in circulation and for helping us to do that.
You've been listening to Circulation on the Run. Don't forget to tune in again next week.
This program is copyright the American Heart Association in 2018.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore.
Our featured paper this week reports the five-year clinical outcomes and valve durability in the largest available cohort to date of consecutive high-risk patients undergoing transcatheter aortic valve replacement. You must listen up for this discussion, coming right up after these summaries.
The first original paper describes a personalized risk assessment platform that promotes the implementation of precision medicine by helping us with the evaluation of a genomic variant of uncertain significance. A genomic variant of uncertain significance is a rare or novel variant for which disease pathogenicity has not been conclusively demonstrated or excluded and thus cannot be definitively annotated. These variants therefore pose critical challenges to the clinical interpretation and risk assessment. New methods are therefore urgently needed to better characterize their pathogenicity.
Co-first authors, Dr Ma, Zhang, and Itzhaki, corresponding author Dr Wu from Stanford University School of Medicine and colleagues recruited a healthy, asymptomatic individual lacking cardiac disease clinical history and carrying hypertrophic cardiomyopathy associated genetic variant in the sarcomeric gene, MYL3, which has been reported by ClinVar database to be likely pathogenic.
Human-induced pluripotent stem cells or IPSCs were derived from the heterozygous carrier, and their genome was edited using CRISPR/Cas9 genome editing to generate karyo-specific IPSCs. Extensive essays, including measurements of gene expression, sarcomere structure, cell size, contractility, action potentials, and calcium handling were performed on the isogenic IPSC-derived cardiomyocytes, and together, the platform was shown to elucidate both benign and pathogenic hypertrophic cardiomyopathy-functional phenotypes.
Thus, this paper demonstrates for the first time the unique potential of combining IPSC-based disease modeling and CRISPR/Cas9 genome editing technology as a personalized risk assessment platform for determining the pathogenicity of a variant of unknown significance for hypertrophic cardiomyopathy in a patient-specific manner.
Transcatheter aortic valve replacement is increasingly being used for the treatment of severe aortic valve stenosis in patients at intermediate risk for surgical aortic valve replacement. The next paper provides real world data comparing indications and clinical outcomes of patients at intermediate surgical risk undergoing isolated transcatheter vs. surgical aortic valve replacement.
Co-first and corresponding others, Dr Werner and Zahn from Clinical Ludwigshafen in Germany compared clinical characteristics and outcomes of more than 7,600 patients with intermediate surgical risk who underwent isolated transcatheter or conventional surgical aortic valve replacement within the prospective all-comers, German aortic valve registry between 2012 and 2014.
Multi-variable analyses reveal that factors that were associated with performing transcatheter instead of surgical aortic valve replacement included advanced age, coronary artery disease, New York Heart Association class three or four, pulmonary hypertension, prior cardiac decompensation, and elective procedure, arterial occlusive disease, no diabetes mellitus, and a smaller aortic valve area.
Unadjusted in-hospital mortality rates were equal for transcatheter and surgical aortic valve replacement, whereas unadjusted one-year mortality was significantly higher in patients with transcatheter aortic valve replacement. After propensity score matching, the difference in one-year mortality was no longer significant. Thus, this large registry analysis suggests that both transcatheter and surgical aortic valve replacement are reasonable treatment options in a real world population with aortic stenosis and intermediate surgical risk.
The next paper demonstrates a key role of vascular endothelial growth factor receptor 1 in hemorrhagic telangiectasia type 2. Now, this is an inherited genetic disorder where haplo-insufficiency of the activin receptor-like kinase 1 gene, ACVRL1, results in blood vessels that are prone to respond to angiogenic stimuli, leading to the development of telangiectatic lesions that can bleed.
First author, Dr Thalgott, corresponding author, Dr Lebrin from Leiden University Medical Center and colleagues used ACVRL mutant mice and found that vascular endothelial growth factor, or VEGF receptor 1 levels were reduced, causing increased VEGF receptor 2 signaling that promoted sprouting angiogenesis, correcting the abnormal VEGF gradient, by expressing membranal-soluble VEGF receptor 1 in embryonic stem cells or blocking VEGF receptor 2 with antibodies in mutant mice, normalized the phenotype both in vitro and in vivo.
Importantly, VEGF receptor 1 was reduced in the blood and skin blood vessels of patients with hemorrhagic telangiectasia type 2 compared with H match controls, demonstrating an important role of VEGF receptor 1 in these patients and explaining why their blood vessels might respond abnormally to angiogenic signals. These findings support the use of anti-VEGF therapy in hemorrhagic telangiectasia type 2.
The next study suggests that hydroxychloroquine could be repurposed to reduce the risk of rheumatic heart disease following acute rheumatic fever. First author, Dr Kim, corresponding author, Dr Wicks from Walter and Eliza Hall Institute of Medical Research and University of Melbourne and their colleagues analyzed the immune response to group A streptococcus in peripheral blood mononuclear cells from an Australian Aboriginal acute rheumatic fever cohort by a combination of multiplex cytokine array, flow cytometric analysis, and global gene expression analysis by RNA sequencing.
They then tested the widely used immunomodulatory drug, hydroxychloroquine for its effects on this response. They found that group A streptococcus activated persistent IL-1 beta production and selective expansion of a specific group of T helper 1 cells that produce GMCSF. Furthermore, hydroxychloroquine limited the expansion of these group A streptococcus-activated, GMCSF-producing T helper cells in vitro.
Gene transcriptional profiling of peripheral blood mononuclear cells from patients with acute rheumatic fever showed dynamic changes at different stages of disease. Given the safety profile of hydroxychloroquine and its clinical pedigree in treating autoimmune diseases such as rheumatoid arthritis where GMCSF plays a pivotal role, the authors therefore proposed that hydroxychloroquine could be repurposed to reduce the risk of rheumatic heart fever following acute rheumatic fever.
The next paper identifies a new anchoring B genetic variant in unrelated Han Chinese probands with ventricular tachycardia. In this paper from co-first authors, Dr Zhu, Wang and Hu, co-corresponding authors, Dr Hong from Second Affiliated Hospital of Nanjing University, Dr Mohler from Ohio State University Wexner Medical Center and colleagues, the authors identified the first anchoring B variant, Q1283H, localized to the ZU5C region in a proband with recurrent ventricular tachycardia.
Knocking mice with this variant showed an increased susceptibility to arrhythmias associated with abnormal calcium dynamics. The variant was associated with loss of protein phosphatase 2A activity, increased phosphorylation of ryanodine receptor, exaggerated delayed after depolarization-mediated trigger activity, and arrhythmogenesis. Furthermore, the administration of metoprolol or flecainide decreased the incidence of stress-induced ventricular arrhythmias, representing potential therapies for anchoring B variant-associated arrhythmias.
Does variability in metabolic parameters affect health outcomes? First author, Dr Kim, corresponding author, Dr Lee from Seoul Saint Mary's Hospital College of Medicine and Catholic University of Korea and their colleagues used nationally representative data from the Korean National Health Insurance system, consisting of more than 6.7 million people who are free of diabetes, hypertension, or dyslipidemia and who underwent three or more health examinations from 2005 to 2012 and were followed to the end of 2015.
Variability and fasting blood glucose and total cholesterol, systolic blood pressure and body mass index was measured using the coefficient of variation, standard of deviation, variability independent of the mean, and average real variability. They found that a high variability in fasting glucose and cholesterol, systolic blood pressure and body mass index was associated with a higher risk for all-cause mortality, myocardial infarction, and stroke. Variabilities in several metabolic parameters had additive associations with the risk of mortality and cardiovascular outcomes in the general population.
These findings suggest that treatment strategies to reduce fluctuations in metabolic parameters may be considered another goal to prevent adverse health outcomes.
How much exercise over a lifetime is necessary to preserve efficient ventricular arterial coupling? First author Dr Hieda, corresponding author Dr Levine from Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center and colleagues studied 102 seniors and grouped them based on their 25 years of exercise training history. The dynamic Starling mechanism was estimated by transfer function gain between beat-by-beat changes in diastolic pulmonary artery pressure and stroke volume index.
They found that there was a graded dose-dependent improvement in ventricular arterial coupling with increasing amounts of lifelong regular exercise in healthy older individuals. Their data suggested that the optimal does of lifelong endurance exercise to preserve ventricular arterial coupling with age appeared to be at least four to five sessions per week. The sufficient lifelong endurance exercise was effective for maintaining the normal dynamic Starling mechanism, left ventricular compliance, and arterial compliance with aging, all of which may lead to favorable effect on cardiovascular stiffness or function.
And that brings us to the end of our summaries this week. Now, for our feature discussion.
Transcatheter aortic valve replacement is taking over the interventional world. It's really rapidly growing, and we're increasingly using it for the treatment of aortic stenosis. It was initially used for inoperable and high-risk patients but now is indicated even in the treatment of intermediate-risk patient, and even low-risk patients are being enrolled into current trials.
So, with TAVR being used for low- and intermediate-risk patients, the longer-term results of this treatment involved your abilities becoming more and more important. Well, gratefully, we have today's feature paper, and it describes the five-year clinical outcomes and valve durability of the FRANCE-2 Registry.
I'm so pleased to have with us the corresponding author, Dr Martine Gilard from University Hospital of Brest in France, we have our editorialist, Dr Anita Asgar from Montreal Heart Institute, and we have our associate editor, Dr Dharam Kumbhani from UT Southwestern.
Martine, congratulations on this largest cohort of high-risk patients and long-term outcomes. Could you please tell us what you found?
Dr Martine Gilard: Yes, and I'll just quote, actually, to have a follow-up of five years. We have 1,200 patients arrive at five years after rotation of TAVI. Each patient was a high-risk patient because it was at the beginning of each treatment, and in this time, it's only the high-risk patient was implanted with TAVI, and actually, we can follow this 1,200 patients, 50% of these patients of these patients have an echography because when we analyze these patients, we have an echography at five years, and the patients who have not echography at five years, the only difference is the age.
It's very old patient. It's very difficult to make this echography on this patient to come back in our center, so it's why there is not all the patient who have an echography at five years.
But our patients who have an echography, we can see that it's a very, very good result at five years. There is always the same area, just after before, of the valve. There is the same gradient. There is not a sign of deterioration.
As you know, we have some guidelines published last year about how we asked to define deterioration of the valve, surgical or TAVI, and if we apply this new recommendation, we saw that in this largest cohort, at five years, there is only 13% of patient who have some sign of deterioration, and of these patients, we never need to make another valve in valve because the deterioration was not so important, and patient leave with this valve like that. There is no necessity to make a new valve in valve, so at five years of this very high-risk patient treated by TAVI, there is no necessity to implant a second valve because the valve deterioration. It's a very, very important message.
Dr Carolyn Lam: Thank you, Martine. Indeed, an important message. And Anita, you wrote a beautiful editorial about it. First, could I ask you to frame the issue? I mean, is there any reason we would expect the durability to be any different from a surgical replacement?
Dr Anita Asgar: I think that's a great question, Carolyn, and I congratulate again Martine and her team for doing a fantastic job to add some very important results to the clinical literature on TAVI. Five years is relatively early to see structural valve deterioration, so in a sense, it's not surprising, and we would consider this sort of medium-term follow-up rather than really long-term durability, but very reassuring that in a high-risk population of patients, that TAVR performs very well in this population of patients and as mentioned, is very low to the dynamic structural valve deterioration.
One question I have for Martine is, as you mentioned, there was only about 12% that had some evidence of structural valve deterioration hemodynamically, but this didn't result in another procedure, and I wonder if you could explain a little bit about that, whether it's the hemodynamic dynamic value, and yet there's a clinical indication for re-intervention. How do you incorporate the two?
Dr Martine Gilard: It's actually hemodynamic deterioration, there is some form of regurgitation. However, there is no need or clinical indication to make another intervention. So, if you compare this research to the bioprostheses surgical paths, the only one who have, at five years, no need to make a re-intervention appearing rotated, which is a valve, a surgical valve we have a longer bioprostheses surgical path.
So, if we compare this best bioprostheses surgical valve, we have sustained results at five years. At five years, we have no need to make a re-intervention because the deterioration was not so important or as needed for clinical evidence as a need to make a new intervention.
Dr Anita Asgar: So, there were some increased rates of heart failure in those patients with structural valve deterioration in your paper, and I know that in the paper you did mention that this is not an adjudicated outcome, and there wasn't a VARC definition for heart failure, but what's your interpretation of increasing heart failure events in these patients with structural valve deterioration?
Dr Martine Gilard: We have no real definition about that. We know that there is another registry. We say that there is an increasing of heart failure, and during the follow-up, and the result of this heart failure increase in mortality. There is an increasing of heart failure, but the number of these patients, there is more. So I don't know if this due to because patient is a high-risk patient, or it's because of the TAVI, but it's very difficult actually to have a real explanation about that.
Dr Carolyn Lam: Thanks, Anita and Martin. Dharam, could you share some of the thoughts and the discussions that were going on behind the scenes with the editors when we saw this paper?
Dr Dharam Kumbhani: Professor Gilard, this was a really excellent paper. We really appreciated you sending it to us, and I think for us, the fact that this was a very large cohort, the largest published cohort that has gotten to five years in a TAVR population, in a multicenter study, and having very good follow-up up to five years, with these patients is always this competing hazard that you want to know what the valve is doing at five years from an echocardiographic and hemodynamic perspective, but there's such a high competing hazard of death, just given the population that you're enrolling, and still, you had one of the largest echo follow-ups on these patients, so we want to congratulate you on the study and really a monumental endeavor, and so really great, great work there.
And I think this is, exactly some of the questions that I think we had and I'm sure that the audience would have as well, I guess the one other question I have, and it's not really a question about your paper. So the median Euro score is 21 in this study, approximately 21, so that's obviously gonna, consistent with the patients that are being enrolled at that time between 2007 and 2012, which were predominantly high-risk and inoperable patients. Can you talk to us a little bit about the landscape of, how is TAVR practice in France as a society or from the regulatory standpoint, what are the benchmarks that you have achieve as you move towards low-risk now? Because intermediate-risk, I'm assuming is a [inaudible 00:20:16], so could you talk to us a little bit about the landscape there?
Dr Martine Gilard: Yes. In France, it's difficult because we have the authority to follow, not immediately, the ESC recommendations, so actually in France, we are allowed to implant only patients with high risk, patients with complication of surgery, and actually just since one year, patients with automatic risk, but we have no authorization to implant patient with low risk.
However, the most important fact is the heart team, and if they write. Because we need to have something written, and if they write, if they explain that it's necessary to implant a patient at low risk because of some point while not including the risk score or it's very difficult to explain, for example, frailty or something, we can implant a patient with low risk.
But normally actually, it is only for complication or high risk and for intermediate risk like the recommendation of the ESC.
So the rate of implantation in France increased because we implant only 2,000 people per year, but actually, in 2017, we have implanted 10,200 patient, and this year, we think that we implant 12,800 patients, so as the number of patients increase, the number of patients who have a very high risk decrease because there is a futile indication, and we have a lot of futile indication, so we doesn't implant patient while too high-risk, and we select the most majority of patient implanted in France was high-risk but also intermediate-risk.
Dr Dharam Kumbhani: So, you think you're implanting more intermediate, like that is a bigger population that is getting TAVIs right now in France?
Dr Martine Gilard: Yes, exactly.
Dr Carolyn Lam: How about perspectives from Montreal? What do you think the implications of this findings from today's paper in relation to the types of patients that you might perform this in now?
Dr Anita Asgar: For us, this is exceptionally reassuring, and as Martine has said, I mean, we have transitioned as well away from that very inoperable cohort C type of patient to more your higher-risk patient or intermediate, and to be honest, everyone over the age of 80 in Canada essentially is getting a TAVR.
Dr Carolyn Lam: Oh, wow.
Dr Anita Asgar: Because regardless of their risk, and we've been very aggressive with that because trying to get patients back to an appropriate quality of life is very important, and to seeing this very reassuring data is telling us that, as she has already mentioned, we have reached the standard, at least in midterm follow-up as the gold standard of surgical valve replacement, and so structural valve deterioration is not as big a concern.
I think we still however need longer-term data when we're looking at lower-risk patients, and lower-risk patients, let's remember, are not 60-year-olds. They're the 75-year-old, perhaps. But we're still gonna need some more data, but it's very reassuring, and patients are asking for it and are really advocating on their behalf to have a less invasive approach, and I think we can say now with more certainty that we know after five years, your chance of structural valve deterioration is actually quite low, and so I think that's very helpful from our point of view.
Dr Carolyn Lam: I love that, Anita, and it's so consistent with the title of your editorial, "Closing in on the Finish Line". Love it, love it, and recommend all listeners pick it up and have a good read. Dharam, I want to leave the last words to you. What do you think are the implications of this paper?
Dr Dharam Kumbhani: Well, I think that, as Anita said, this is very encouraging results that, in this kind of extreme and high-risk patient cohort, that there appear to be no medium- to long-term signals of structural valve degeneration, that the biggest hazard from this procedure is all upfront, and after that, it's pretty much, it's as we have seen with surgery, that after that, the actuarial rates come back to what you would expect.
If they didn't have aortic stenosis and then they would die from whatever causes they had. Now obviously, that wasn't tested, but it seems like looking at the curves, that that seems like what's going on, so I think they've done a great service to our TAVR community in terms of showing us these results in very large, multicenter cohorts from France.
Dr Carolyn Lam: Thank you so much for joining us today. Thank you, listeners. You've been listening to Circulation on the Run. Don't forget to tune in again next week.
This program is copyright American Heart Association, 2018.
Dr Carolyn Lam: Welcome to Circulation on The Run, your weekly podcast summary and backstage pass to the journal and it's editors. I'm Dr Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore. We will be discussing accelerated diagnostic protocols for chest pain, a very, very important issue in Cardiology with very important new safety and effectiveness data on one such protocol provided in our feature paper this week. Coming right up after these summaries.
Our first original paper this week identifies a new link between specific gut bacteria and atherosclerosis. Co-First authors, Dr Yoshida and Emoto, corresponding author, Dr Yamashita, from Kobe University Graduate School of Medicine, and colleagues recruited patients with coronary artery disease and controls without coronary artery disease but with coronary risk factors. They then compared gut microbial composition using 16S ribosomal RNA gene sequencing in fecal samples. Subsequently, they used atherosclerosis prone mice to study the mechanisms underlying the relationship between such species and atherosclerosis. Their analysis of gut microbial profile in patients with coronary artery disease showed a relative depletion of bacteroides vulgatus and bacteroides dorei compared to controls with coronary risk factors. Gavage with live bacteroides vulgatus and bacteroides dorei decreased fecal and plasma lipopolysaccharide levels and protected against atherosclerosis in apoE deficient mice. Fecal lipopolysaccharide levels in patients with coronary artery disease were significantly higher compared to controls. These findings suggest that bacteroides treatment may serve as a novel and effective therapeutic strategy for suppressing lipopolysaccharide-induced inflammatory response in coronary artery disease.
The next paper identified a potential novel molecular target in the treatment of myocarditis. Co-First authors, Dr Chen and Zeng, Co-Corresponding authors, Dr Song from Fuwai Hospital in Beijing, and Dr Yang from Shenzhen University School of Medicine, and their colleagues aim to elucidate the role of BCL2 Like protein 12 in the pathogenesis of biased T Helper-2 response in myocarditis. Using a combination of mouse models of myocardial inflammation and human hearts from patients undergoing heart transplantation, the authors found that CD4 positive T-cells isolated from hearts in myocarditis at the end stage of heart failure expressed high levels of BCL2 Like protein 12, which was required for the development of aberrant T Helper 2 polarization in the heart. Thus, BCL2 Like protein 12 may be a novel target in the treatment of myocarditis, as well as other T Helper 2 biased inflammatory processes.
Could vaccination against LDL be a way to prevent atherosclerosis? Well, the next paper brings us one step closer to this dream. First author, Dr Gisterå, corresponding author, Dr Hansson from Karolinska School University Hospital and colleagues developed T-cell receptor transgenic mice to study LDL autoimmunity in a humanized hypercholesterolemic mouse model of atherosclerosis. A strong T-cell dependent E-cell response was induced by ODL leading to production of anti-LDL IgG antibodies that enhanced LDL clearance and ameliorated atherosclerosis. Results show that anti-LDL immuno-reactivity evoked three atheroprotective mechanisms, namely 1) antibody-dependent LDL clearance, 2) increased cholesterol excretion, and 3) reduced vascular inflammation, thus targeting LDL-reactive T cells may enhance atheroprotective immunity, and vaccination against LDL components may be an attractive way to prevent atherosclerosis.
MicroRNAs regulate nearly all biological pathways and dysregulation of MicroRNAs is known to lead to disease progression. However, are there cell type specific effects of MicroRNAs in the heart? Co-First authors, Drs Rogg and Abplanalp, corresponding author, Dr Dimmeler from Goethe University Frankfurt, and colleagues assessed MicroRNA target regulation using MicroRNA 92a3p as an example. Their data showed that MicroRNAs have cell type specific effects in vivo which would be overlooked in bulk RNA sequencing. Analysis of MicroRNA targets in cell subsets disclosed a novel function of MicroRNA 92a3p in endothelial cell autophagy and cardiomyocyte metabolism. These findings may have clinical applications for the fine tuning of autophagy and metabolism to mitigate tissue damage in patients with cardiac disease.
The next paper establishes a mechanism by which cardiac inflammation may be initiated in response to hemodynamic stress, but in the absence of significant cardiomyocyte cell death. Co-First authors, Drs Suetomi and Willeford, Co-Corresponding authors, Drs Brown and Miyamoto from University of California San Diego, and their colleagues used conditional cardiomyocyte-specific calcium calmodulin-regulated kinase Delta all CaM kinase II Delta knockout mice to demonstrate that cardiomyocytes generate inflammatory chemokines and cytokines and are the initial site of NLRP3 inflammasome activation. They further identified a causal role for CaM-Kinase II Delta-mediated activation of NLRP3 inflammasome and inflammatory responses in macrophage recruitment, cardiac fibrosis, and development of heart failure induced by pressure overload. Their elegant mouse experiments revealed sites and mechanisms of proinflammatory gene and inflammasome activation within cardiomyocytes which could serve as targets for early intervention or disease prevention.
Are there different metabolomic effects between PCSK9 inhibitors and statins? First author, Dr Sliz, Corresponding Author, Dr Würtz from Nightingale Health Limited in Helsinki, Finland, and their colleagues quantify 228 circulating metabolic measures by Nuclear Magnetic Resonance Spectroscopy for over 5300 individuals in the PROSPER Trial at six months post randomization. The corresponding metabolic measures were also analyzed in eight population cohorts, including more than 72,000 individuals using a specific PCSK9 inhibitor SNP as an unfounded proxy to mimic the therapeutic effects of PCSK9 inhibitors. Scaled to an equivalent lowering of LDL cholesterol the effects of genetic inhibition of PCSK9 on these 228 metabolic markers were generally consistent with those of statin therapy. Alterations of lipoprotein lipid composition and fatty acid distributions were also similar. However, discrepancies were observed for very low-density lipoprotein or VLDL lipid measures where genetic inhibition of PCSK9 had weaker effects on lowering VLDL cholesterol compared with statin therapy. Genetic inhibition of PCSK9 showed no significant effects on amino acids, ketones, or a marker of inflammation, where a statin treatment weekly lowered this marker of inflammation. Thus, if VLDL lipids have an independent causal effect on cardiovascular disease risk, the observed discrepancy on VLDL lipid lowering could contribute to differences in cardiovascular risk reduction between statins and PCSK9 inhibitors for an equivalent reduction in LDL cholesterol. Moreover, these results exemplify the utility of large-scale metabolomic profiling with genetics and randomized trial data to uncover potential molecular differences between related therapeutics.
The final original paper this week demonstrates a novel biomarker discovery paradigm to identify candidate biomarkers of cardiovascular and other diseases. Co-First authors, Dr Mosley and Benson, co-corresponding authors, Dr Wang from Vanderbilt University Medical Center and Gerszten from Beth Israel Deaconess Medical Center, and their colleagues employed a virtual proteomic approach linking genetically-predicted protein levels to clinical diagnosis in more than 40,000 individuals. They used genome-wide association data from the Framingham Heart Study to construct genetic predictors for more than 1100 plasma protein levels. They validated the genetic predictors for 268 proteins and used them to compute predicted protein levels in more than 41,000 genotyped individuals in the eMerge Cohort. They tested associations for each predicted protein with more than 1100 clinical phenotypes. These associations were validated using directly-measured protein levels and either LDL cholesterol or subclinical atherosclerosis in the Malmo Diet and Cancer study. Using this virtual biomarker strategy the authors identified CLC1B and PDGFR Beta as potential circulating biomarkers of atherosclerosis and validated them in an epidemiologic cohort. Thus, these results demonstrate that a virtual biomarker study may efficiently identify potential biomarker disease associations, and that wraps it up for our summaries. Now for our feature discussion.
Accelerated diagnostic protocols for testing are used everywhere. They're designed to improve the quality and value of chest pain risk stratification. However, many of them lack sufficient prospective safety and effectiveness data. We're so pleased to have a paper today that provides such important data on one of these accelerated diagnostic protocols for chest pain, and it's the HEART Pathway. To discuss this, I've got the corresponding author of today's featured paper, Dr Simon Mahler from Wake Forest School of Medicine, as well as our Associate Editor, Dr Deb Diercks from UT Southwestern. Simon, could you start by just telling us, what is the HEART Pathway?
Dr Simon Mahler: Sure. Yeah, it's an accelerated diagnostic protocol. It's based on an accelerated diagnostic protocol called the HEART Score. We use a modified version of the Heart Score. We actually use a HEAR score, and that stands for the history, EKG, Age, and risk factors. That is combined with two troponin measures at 0 and 3 hours. We also factor in whether or not the patient has had prior coronary artery disease or has an acute ischemic EKG. So, to be low-risk you have to have a HEAR score of 0-3. HEAR is an acronym. You get points for each of those categories. If you have less than 3 points that's a low score. You have to have a low score, a non-ischemic EKG, no history of prior coronary disease, and two troponins less than a 99th percentile at 0 and 3 hours to be considered low risk and recommended for early discharge. If you don't meet any of those criteria then you are considered non-low risk and appropriate for further in-hospital evaluation.
Dr Carolyn Lam: That's great. Could you just tell us what you did to give us some real-world safety and effectiveness data on this.
Dr Simon Mahler: Yeah, so we had done a single-site randomized controlled trial. That was published in 2015 in Circulation: Quality and Outcomes, and really showed some promising results. We received some funding to do an implementation trial. So, this is the results of our implementation study. It's a before and after study. What we did was we sought to implement a HEART Pathway as a clinical decision support tool, integrated fully into our electronic medical record so that when providers see the patient with chest pain and order a troponin they interact with a HEART Pathway tool that guides them through the HEART Pathway risk assessment and then provides real-time decision support regarding their treatment and disposition decisions based on whether or not the patient has a low-risk assessment or a non-low-risk assessment. The design of the study was we collected data on all patients with chest pain and troponin order for one year while we worked on how we were gonna build this tool and embed it, and then we had three month watching period where we built the tool into the electronic health record across our three sites. Then, we had one year where we were post implementation where we collected data and looking at the difference in outcomes, particularly looking at both safety and utilization outcomes before and after use of the HEART Pathway.
Dr Carolyn Lam: That's just such a clever design. Just give us a summary of the results before I ask Deb to chime in here.
Dr Simon Mahler: There's a few really important things that we found. Probably the most important thing was the safety data that came out of this study. We had some good safety signals on prior studies. They didn't have enough sample size to really have a good precision around the safety point estimate, so in this study we had over 4000 patients in our post-implementation cohort, and about 31%, 30.7%, of those patients were classified as low-risk by the HEART Pathway. Among those patients that were classified by low-risk, the rate of death and MI, the composite outcome at 30 days, was 0.4%. Typically for these accelerated diagnostic protocols we want them to have an adverse cardiac event rate less than 1%, so a finding of 0.4% with a confidence in our role that doesn't extend beyond 1% that was a really important finding that really confirms the safety of this strategy.
The other thing that we found which was interesting was that the use of the HEART Pathway was actually associated with detecting more myocardial infarctions during the index visit, which means that possibly the HEART Pathway use improved the recognition of those patients that were presenting with MIs. It's possible that without using the HEART Pathway some of those cases may have been missed. Finally, we were able to demonstrate that use of the HEART Pathway as a clinical decision support tool was able to decrease hospitalizations and some other utilization metrics such as stress testing and possible length of stay.
Dr Carolyn Lam: Oh, that's awesome, Simon. I said it earlier. I'm gonna say it again. Thank you so much for publishing this wonderful work with Circulation. I really think that implementation, science, and decision support tools you've got that all in this paper, just beyond even the actual topic. Deb, take us behind the scenes a little bit with how we reacted as editors to this paper, please.
Dr Deb Diercks: Well, I think that overall, we were really excited about this paper. It really does add a real, real context to something we were really discussing and wondering about. I think one of the great things about the implementation, and Simon, please comment on this, is the diversity of the places that you actually used this in. I mean, most of us when we look at papers there's always a fear that it won't be able to be generalized to real-world practices. Correct me if I'm wrong, but you really applied it to just a wide variety of Emergency Departments that really support that this could be used anywhere.
Dr Simon Mahler: Yeah, I think that's a really important point, that we did this across our system so that included a large academic busy Emergency Department that sees over 100,000 patients per year, all the way, basically to a smaller 12,000 per year, essentially almost a free-standing Emergency Department at the time that we started our study; it now has inpatient bed capacity, and then a suburban/rural hospital, as well, with about 30,000 patient visits per year. We extended beyond kind of the typical kind of comfort zone of large academic centers and into smaller community Emergency Departments as well.
Dr Deb Diercks: One of the things that this manuscript nicely articulated is that you kind of break it into the HEAR and then the troponin.
Dr Simon Mahler: Right.
Dr Deb Diercks: Things change in the US with troponin. How do you think that's gonna impact how you guys apply this Pathway in the future?
Dr Simon Mahler: It's a big topic of discussion right now, what to do with these Pathways. Are these Pathways still needed with the availability now of high-sensitivity troponins in the United States? I think that for many years as we've kind of followed data coming out of Europe we've been anxiously awaiting the arrival of these tests in the U.S., and there's a lot we can learn from the European data so far. Most of that data suggests that the high-density troponins are best used still in the context of a Pathway or an accelerated diagnostic protocol.
I think that this particular study was conducted just using contemporary troponins, particularly given the time frame of the study in which we were accruing patients from 2013 through 2016, but I think it's still gonna be highly relevant, because I think that best practices are gonna still require us to use some sort of structured framework with high-sensitivity troponins. Now, it does remain to be seen a little bit what the best Pathway is gonna be to incorporate that. My take on this is that I believe that clinical decisions support tools or decision aids integrated with high-sensitivity troponins is going to be the best way to go. I'm a little bit skeptical about troponin-only approaches.
Dr Deb Diercks: That's a great summary. I don't think it's time to throw out all the value of that risk stratification tool, and I think your study showed that how it can easily be incorporated into what we do in a manner that doesn't really negatively impact the work flow, which I think is so important.
Dr Simon Mahler: You know, we did a smaller study where we looked at the performance of the HEART Pathway with high-sensitivity assays. We studied it with both the Roche troponin high-sensitivity troponin T and the Abbott high-sensitivity I, and at the 99th percentile it actually made very little difference in terms of the performance of the HEART Pathway. What the potential advantages of incorporating high-sensitivity assays is that you probably no longer need a 0 and 3 hours, evaluation can be condensed. I think there's a lot of really interesting questions that availability of high-sensitivity troponins has created, and I think that there's gonna be a lot of emerging evidence over the next few years about new Pathways, and what are the best ways to fully take advantage of these higher-sensitive assays because, frankly, most of the decision aids that are currently in use they were developed using contemporary troponins, and they may not fully take advantage of high-sensitivity troponins. We may see modifications of our Pathway, and it will interesting to see kind of how things evolve as we study the impact of high-sensitivity troponin.
Dr Carolyn Lam: Wow, exciting work ahead. Just one last question regarding the future. So, you followed up the patients in your study for 30 days. Am I wrong? Any plans to follow them up longer, and do you think such data are needed?
Dr Simon Mahler: Yeah, we actually followed them for a year. Our primary analysis was through 30 days, and so we do have one-year data on all of our patients, and so we'll be doing a secondary analysis looking out to a year. Yeah, you can look forward to that coming up hopefully in the next six months or so.
Dr Carolyn Lam: That is awesome. Thank you so much, Simon. Thank you so much, Deb. Thank you, listeners, for joining us today. You've been listening to Circulation on the Run. Don't forget to tune in again next week. This program is copyright American Heart Association 2018.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore.
Is there a unique lipoprotein profile for incident peripheral artery disease as opposed to coronary or cerebral vascular disease? Well, you're just gonna have to wait for our feature discussion to find out. That's coming right up after these summaries.
Our first original paper this week tells us that gene variance known to be associated with idiopathic and peripartum cardiomyopathy are also associated with preeclampsia. First and corresponding author Dr Gammill from University of Washington and colleagues studied 181 participants with confirmed preeclampsia from the Preeclampsia Registry in BioBank. Saliva samples were collected for DNA isolation and whole exome sequencing was performed to detect rare variants in 43 genes known to be associated with cardiomyopathy.
Results were compared with data from two controlled groups, unrelated women with a gynecological disorder, sequence using the same methods and instruments, as well as published variant data from 33,000 subjects in the Exome Aggregation Consortium.
The results showed that women who developed preeclampsia are more likely to carry protein altering mutations in genes associated with cardiomyopathy, particularly, the TTN gene which encodes the sarcomeric protein titin. Thus, detecting these gene variants may allow more specific diagnosis, classification, counseling and management of women at risk.
Prior trials have shown that nonsteroidal anti-inflammatory drugs or NSAIDS confer cardiovascular risk. Now this has been postulated to be due to enhanced formation of methyl arginines in the kidney that would limit the action of nitric oxide throughout the vasculature. However, the next original paper in this week's journal suggests that this may not be correct. First author, Dr Ricciotti, corresponding author, Dr FitzGerald from University of Pennsylvania Perelman School of Medicine and colleagues, used multiple genetic and pharmacological approaches to disrupt the COX 2 pathway in mice and analyze plasma from patients taking NSAIDS.
However, they did not observe an increase in methyl arginines. In contrast, they did observe an increase in plasma asymmetric dimethylarginine or EDMA in mice-rendered hypertensive by infusion of angiotensin II at a dose that also caused renal impairment. After a four week washout period following the infusion of angiotensin II, blood pressure, creatinine, and ADMA levels all fell back to normal levels.
Celecoxib-treated mice also exhibited increased ADMA and plasma creatinine in response to infusion of angiotensin II and their levels also returned to normal thereafter. Thus, it seems likely that the previous reported elevations in ADMA reflected renal dysfunction rather than a direct consequence of COX 2 deletion or inhibition. The authors end by suggesting that the most plausible mechanism by which NSAIDS confer a cardiovascular risk, is by suppression of COX 2 derived cardioprotective prostaglandins such as Prostacyclin rather than by enhanced formation of methyl arginines.
The next original paper identifies new targets with the potential to prevent vascular malformations in patients with hereditary hemorrhagic telangiectasia. Co-corresponding authors, Dr Ola and Eichmann from Yale University School of Medicine and colleagues looked at SMAD4, which is a downstream effector of transforming growth factor-beta/bone morphogenetic protein family ligands that signal via activin-like kinase receptors.
The authors generated a tamoxifen inducible postnatal endo-fetal specific SMAD for a mutant mouse and showed that SMAD4 prevented flow-induced arterial venous malformations by inhibiting casein kinase II. The uncovered pathways provided novel targets for the treatment of vascular lesions in hereditary hemorrhagic telangiectasia related juvenile polyposis patients carrying SMAD4 mutations.
The next original paper provides important data for the accurate diagnosis of long QT syndrome. Long QT syndrome can be a challenging diagnosis partly because the optimal method for QT assessment is not unequivocally established. QT experts advocate manual measurements with a tangent or threshold method.
In today's paper, first and corresponding author, Dr Vink from Academic Medical Center University of Amsterdam and colleagues, aimed to assess similarities and differences between these two methods of QT interval analysis among 1,484 patients with a confirmed pathogenic variant in either KCNQ1, KCNH2 or SNC5A genes from 265 families. Both QT measurement methods yielded a high inter and intra reader validity and a high diagnostic accuracy.
Using the same current guideline cutoff of QTC interval 480 milliseconds, both methods had similar specificity but yielded a different sensitivity. QTC interval cutoff values for the QT measured by the tangent method was lower compared to that measured by the threshold method. Plus, values were different depending on the correction for heart rate, age, and sex.
The authors provided an adjusted cutoff values specified for method, correction formula, age, and sex. In addition, a freely accessible online probability calculator for long QT syndrome at www.QTcalculator.org has been made available as an aid in the interpretation of the QT interval.
The next original paper demonstrates for the first time that thrombin mediated signaling may play a role in diet-induced atherogenesis. Co-first authors, Dr Raghavan and Singh, corresponding author Dr Rao from University of Tennessee Health Science Center and colleagues, used a mouse model of diet-induced atherosclerosis and molecular biological approaches and explored the role of thrombin and its G protein coupled receptor signaling in diet-induced atherosclerosis.
They found that thrombin-induced CD36 expression and foam cell formation required protease activated receptor 1, G alpha 12, Pyk2, GAB 1, and protein kinase C theta dependent activating transcription factor 2 activation. Thus, inhibition of thrombin G protein coupled receptor signaling could be a promising target for the development of new drugs in reducing the risk of diet-induced atherogenesis.
The next study provides insights into the long- term association of LDL cholesterol with coronary heart disease mortality in individuals at low tenure risks of atherosclerotic cardiovascular disease. First and corresponding author, Dr Abdullah, from VA North Texas Medical Center and UT Southwestern Medical Center and colleagues studied more than 36,000 subjects in the Cooper Clinic Longitudinal Study cohort who are at low tenure estimated risk of atherosclerotic cardiovascular disease. In other words, a low tenure risk of less than 7.5%. They've followed these patients for more than two decades.
Results showed that LDL cholesterol and non-HDL cholesterol at or above 160 milligrams per deciliter were independently associated with a 50 to 80% increased relative risk of cardiovascular disease mortality. The associations between LDL cholesterol and cardiovascular disease mortality were more robust when follow up was extended beyond the traditional 10 year estimated risk period.
The associations remain significant in those with an estimated tenure atherosclerotic cardiovascular disease risk of less than 5%. These data suggests that LDL cholesterol levels at or above 160 milligrams per deciliter in individuals deemed to be at low tenure atherosclerotic cardiovascular risk are associated with worse long term cardiovascular disease mortality. These findings, along with other observational data and data extrapolated from clinical trials, support further consideration of appropriate LDL cholesterol thresholds for lipid lowering interventions in individuals categorized as low short-term risk.
The final paper this week uncovers a novel therapeutic target for the prevention and treatment of thoracic aortic aneurysms. First author, Dr Nogi, corresponding author Dr Shimokawa from Tohoku University Graduate School of Medicine and colleagues, used genetically modified mice to show a pathogenic role of the small GTP binding protein, GDP dissociation stimulator in the development of angiotensin 2 induced thoracic aortic aneurysms and dissection. Down regulation of this protein contributed to dysfunction of aortic smooth muscle cells and hence oxidative stress, and matrix metalloproteinase activities in the pathogenesis of thoracic aortic aneurysms and dissection.
Local over expression of this small GTB binding protein GDP dissociation stimulator around the thoracic aorta inhibited aortic dilatation and rupture in deficient mice. And that wraps it up for this week's summaries. Now for our feature discussion.
Atherosclerosis has been considered a systemic process, meaning that when we see a disease in one vascular bed, we assume that that's a risk marker for disease in other vascular territories, and that they share pathophysiology, they share risk factors. However, if we think about it, the prior studies have all been sort of focusing on coronary and cerebral vascular disease, but today's feature paper changes that a bit because it addresses a key knowledge gap in peripheral artery disease risk, and interestingly suggests that there may be a unique lipid profile that's related to peripheral artery disease.
This is gonna be an exciting discussion and I have the first author, Dr Aaron Aday from Vanderbilt University Medical Center currently. We have our editorialist, Dr Parag Joshi from UT Southwestern, and our associate editor, Dr Anand Rohatgi from UT Southwestern. Welcome gentlemen and Aaron, could we start with you sharing about your study?
Dr Aaron Aday: So, as you mentioned, a lot of the previous epidemiologic data on atherosclerosis have been primarily in coronary artery disease and stroke, and when we looked at peripheral artery disease or PAD, there seemed to be some subtle differences. So for instance, total cholesterol on HTL cholesterol seemed to be the strongest risk factors for future peripheral artery disease and in terms of LDL cholesterol, the data are somewhat mixed. Some have found a weak association, some have actually found no association. And so building on that, we wanted to see if using nuclear magnetic resonance spectroscopy, we could elucidate more details about the litho protein pathways associated with peripheral artery disease.
And we did this in the women's health study which is a prospective cohort study of women free of cardiovascular disease, the baseline, they were aged 45 and older. And what we've found in terms of the standards with their profiles, we again found that there was no association between LDL cholesterol and future peripheral artery disease, whereas certain standard lipid measures like HDL cholesterol were strongly associated with PAD, and then using the Endemol spectroscopy tool, we found that actually, small LDL particles and total LDL particles were concentrations of both of those markers, were strong risk factors for future PAD and other measures like total HDL particle concentration were even more strongly associated with future PAD than coronary artery disease.
So essentially the signature associated with future peripheral artery disease, had some important differences than that for a composite of coronary artery disease and stroke.
Dr Carolyn Lam: Aaron thanks for that. That's beautifully described and just so intriguing. Parag, could you tell us how should we be thinking about results like this?
Dr Parag Joshi: It's a great paper and it really highlights a new and unique approach in that we ... Peripheral artery disease as an isolated incident event is fairly understudied I guess we could say and so, this is a really nice paper to start choosing out some of the risk factors for that. I think overall, when we think of peripheral arterial disease in general, I think historically, we've thought of it as similar pathophysiology, you know LDL particles and perhaps other particles depositing in the arterial space. But this does highlight some important differences that might exist and I think one of those seems to be that maybe this is more a signature of elevated remnant lipoproteins or triglyceride rich remnant lipoproteins, small dent LDL particles, low HDL, that sort of metabolic syndrome type patterns that we look at as a high risk factor that may be more contributory to peripheral artery disease than coronary disease, or at least more specific to peripheral artery disease.
I guess one of my main questions about that from your work Aaron is, how can we be sure this isn't just a pre-clinical marker of diabetic patients which we know have this type of pattern?
Dr Aaron Aday: Sure, it's certainly a possibility. I think what's notable in the cohort, at least a time enrollment. And there was a very little diabetes and actually there was a much greater prevalent of metabolic syndrome. So in my mind, it may be more of a metabolic syndrome specific marker rather than necessarily down the diabetes pathway, but it's certainly something that needs to be explored further.
Dr Parag Joshi: I wonder whether women's health studies such a healthy cohort that I wonder if this is picking up some signal before the answer to diabetes or as you said, metabolic syndrome, you know which certainly suggests an insulin resistance pattern and we know the association of diabetes with peripheral artery disease is stronger and so I wonder if this may be a sort of earlier way of picking that up.
Dr Aaron Aday: It may be. I think one thing to notice is the outcome of peripheral artery disease that we're using. So it is symptomatic disease. So, we're not picking up a lot of ulcers that are developing in the future, it's more the claudication and then people who've undergone revascularization. Certainly diabetics have both of those as well but I think that may suggest it's not fully unexplained by developing diabetes than peripheral artery disease further down the line.
Dr Parag Joshi: Yeah that's a great point.
Dr Carolyn Lam: Yeah great questions, great thoughts. Anand, what about you? Did you have questions too?
Dr Anand Rohatgi: I think from my perspective and thinking about it for circulation and its readership, we found this really interesting for several reasons. Number one, I think is, as you all have discussed, peripheral arterial disease just is not as well characterized and you can see that here in over 25,000 people, add about a 100 a bed, so I think in younger folk, it takes a lot of people to study, to be able to really understand kind of the pathophysiology of peripheral arterial disease.
The other thing that they think they really shed some light on is how this is happening in women in particular and in women, of course as we know have been understudied in all cardiovascular diseases, but in particular, diseases like this which are less common. It's really insightful to see that these lipid abnormalities in women are contributing to peripheral arterial disease more so than your typical LDL cholesterol management and interestingly enough, most of the women who had PAD events in this study, did not have other cardiovascular events.
They really just had PAD events exclusively and I thought that was really intriguing, and the use of this advanced lipoprotein testing, this NMR modality has been very useful in terms of biology and research, and I think that's the case here where we really go under the hood Carolyn, as you said, and get kind of deep dive, the lipid metalobles on abnormalities. And I think Parag and Aaron hit the nail in the head that this is really capturing an insulin resistance of phenotype and what I really liked about this is, instead of studying people who are 70, 80 years old and a lot of things are sort of clustering, a lot of diseases are clustering and they're manifesting all at the same time, it's very hard to tease apart the effective age.
Here, we captured women in their 50s and middle aged, just as they have kind of gone through menopause and this adverse metabolite's phenotype starts to rise in women. And then we could follow them over time and see what the natural history of that is, and the women who have this phenotype go on to have this devastating consequence, this peripheral arterial disease. One of the questions I had then, Aaron for you is, what do you think the implications are from these findings? Does it mean that in terms of diagnostics, we should be doing more advanced testings looking at LDL and HDL type particles with NMR or some other mortality? Does it change therapies with new therapies beings studies right now? What do you think the implications are from your work?
Dr Aaron Aday: That's important right. I think you mentioned this and I see the inter marked tool in this study, is really a way to try to dig further into the biology of peripheral artery disease as a form of atherosclerosis. I think that we already know patients who are extremely high risk or PAD, those are patients with diabetes, smoking history, metabolic syndrome et cetera., and as you can see in a patient population in 28,000 middle aged women who are pretty healthy, we only had just over a 100 PAD events.
So, I think even if you were to scale this up in terms of cost, I'm not sure that that would necessarily be a viable option for patients, but I think it does suggest that truly focusing on LDL in a very high-risk patient population, meaning patients with PAD, or we may not be fully addressing their risk. And so I think this is a need to highlight that important gap, think about other therapeutic options and we'll soon have ongoing trials, triglyceride low in therapy that may be particularly beneficial in this patient population and so that's how I see this being used.
Dr Anand Rohatgi: That makes a lot of sense and particular because in middle aged women like this, your standard risk score algorithms will not really capture that they're at increased risk, even if they smoke, just because they're women and they're younger and so, I think this really is a call to arms to more refined risk assessment in these women.
Dr Parag Joshi: Aaron, do you think there's actually a difference in the biology in the peripheral arteries compared to the coronary and cerebral vascular beds, or is there data to kind of look at that or maybe histopathological data to look at that?
Dr Aaron Aday: We know there's a lot of overlaps, so I don't wanna suggest that PAD is not a former atherosclerosis. I think one limitation is that the primary animal model for PAD is the hyperCKemia model. That doesn't fully recapitulate what's happening in a limb with PAD and so I think that has been one limitation in understanding the biology. But I think what we're starting to see in some clinical trials that have come out in the last couple of years or starting to see a somewhat different signal for therapies in patients with PAD so for instance, in 48, we actually saw that there was a greater benefit to LDL lower [inaudible 00:21:00] inhibitors than for coronary disease. We now have the compass trial results, again, more events, higher risk among these patients but for their benefit, add on River Oxodine therapy, we've seen lymph events or lymph signals in the SGLP2 inhibitor trials. So, I think we're starting to get a sense that there may be something else on top of the traditional ascariasis biology that may be a potential target on down the road.
Dr Parag Joshi: I think it's really a fascinating biological question of how these different territories might actually differ in their pathophysiology. I think it's a really a nice time to look at this. Also I think, Anand and Aaron both mentioned ongoing trials. The omega 3 fatty acid trials I think reduce it, will be soon to be presented and hopefully published in the next month or so. It would be nice to see if they evaluate peripheral events in that group, I'm sure they will.
Dr Carolyn Lam: Indeed, these have been just such great thoughts and discussion. Nothing really much to add there. I suppose I could say something cheeky like for the first time, and I never thought I'd say it on the podcast, I feel kind of bad that there are no men included in this trial but anyway, I just learnt so much from this. I just wanna thank you gentlemen for a great discussion.
Thank you, listeners, for joining us today and don't forget to tune in again next week to Circulation on the Run.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore.
This week's feature discussion focuses on first and man pilot study results of pericardiotomy and its influence on left ventricular diastolic reserve with volume loading. Very fascinating implications for heart failure with reserved ejection fraction, coming right up after these summaries.
Cardiac dysfunction is a major component of sepsis-induced multi-organ failure in critical care units. But what are the underlying mechanisms and potential therapeutic approaches to this? Well, in today's paper from co-first authors Drs Sun and Yao, corresponding author Dr Chang, and colleagues from UT Southwestern Medical Center, the authors examine the status of cardiac autophagy and its role during sepsis pathogenesis using a rodent lipopolysaccharide-induced sepsis model. They've found that forced overexpression of Beclin-1 in the heart promoted autophagy and mitophagy, protected mitochondria, improved cardiac function, and alleviated inflammation and fibrosis after a lipopolysaccharide challenge. Whereas, haplosufficiency for Beclin-1 resulted in the opposite effects. For the more injection of a cell permeable Tat-Beclin-1 peptide improved outcomes in lipopolysaccharide-challenged animals. Thus promoting Beclin-1-dependent signaling may be a novel and effective intervention to alleviate organ dysfunction caused by maladaptive autophagy during severe sepsis.
The next paper presents important experimental data that causes us to consider the potential cardiovascular hazards of anti B-cell activating factor immunotherapy, which is currently approved for the treatment of autoimmune systemic lupus erythematosus. You see, genomic data has shown that B-cell activating factor receptor pathway is specifically essential for the survival of conventional B lymphocytes, which is a key driver of coronary heart disease. However, in today's paper from co-first authors, Drs Tsiantoulas and Sage, corresponding author Dr Binder and colleagues from Medical University of Vienna, the authors reported an unexpected finding that B-cell activating factor neutralization increased atherosclerotic plaque size and complexity despite efficient depletion of mature, conventional B lymphocytes. Furthermore, the authors provided evidence suggesting a novel B-cell independent anti-inflammatory property of B-cell activating factor. They showed that the expression of the alternative B-cell activating factor binding receptor, transmembrane activator and CAML interactor in myeloid cells limited atherosclerosis thus showing novel atheroprotective pathways. Thus, these results introduce a new perspective with respect to the potential cardiovascular hazards that may be associated with the long term blockade of B-cell activating factor in chronic inflammatory settings. There is a need for more refine therapeutic approaches targeting the B-cell activating factor pathway.
Vascular smooth muscle cells are known to possess remarkable plasticity undergoing fundamental phenotypic switches from a differentiated to a dedifferentiated state in response to vascular injury or remodeling. However, what are the underlying cellular processes by which vascular smooth muscle cells maintain their cell identity? Well, in today's paper from co-first authors Dr Yao, Yu and Li, corresponding Dr Wang from Fu Wai Hospital National Center for Cardiovascular Diseases, Chinese Academy of Medical Science and Peking University Medical College. The authors applied single cell RNA sequencing to analyze disease human arteries and identified histone variant H2A.Z as a key histone signature that maintains vascular smooth muscle cell identity. H2A.Z occupied genomic regions near vascular smooth muscle cell marker genes and it's occupancy was decreased in vascular smooth muscle cells undergoing dedifferention. H2A.Z expression was dramatically reduced at both messenger RNA and protein levels in diseased human vascular tissues compared to those in normal arteries. Notably, in vivo overexpression of H2A.Z rescued injury-induced loss of vascular smooth muscle cells identity and new intima formation. Together, these data introduced dynamic occupancy of a histone variant as a novel regulatory basis contributing to cell fate decisions and implied that H2A.Z may be a potential intervention known for vascular diseases.
What is the causal role of body mass index and cardiovascular health in young adults? In the next paper from first and corresponding author Dr Wade from University of Bristol in United Kingdom and her colleagues. The authors used a combination of conventional multivariable regression analyses, Mendelian randomization and subsample recall by genotype methodologies. Recall by genotype is a novel approach that exploits the random assortment of alleles through meiotic cell division at conception to inform genetically base recall and enables the collection of precise phenotypic measures in smaller studies while maintaining statistical power and ability for causal inference. The authors use these methods to estimate the causal effect of body mass index on gross level and detail cardiovascular health in healthy participants from the Avon longitudinal study of parents and children at age 17 years as well as in an independent sample from the same cohort study at age 21 years.
Their results showed that higher body mass index was likely to cause worse cardiovascular health specifically higher blood pressure and higher left ventricular mass index even in youth. Higher body mass index also resulted in increased cardiac output in the recall by genotype study which appeared to be solely driven by stroke volume, as neither the Mendelian randomization nor the recall by genotype analyses suggested a causal effect of body mass index on heart rate. These consistent results support efforts to reduce body mass index from a young age to prevent later adverse cardiovascular health and illustrate the potential for phenotypic resolution with maintained analytical power using a recall by genotype methodology.
Older adults undergoing aortic valve replacement are at risk for malnutrition, however, what is the association between pre-procedural nutritional status at midterm mortality? First author, Dr Goldfarb, corresponding author Dr Afilalo from McGill University in Montreal, Quebec, reported results of the FRAILTY-AVR prospective multicenter international cohort study conducted between 2012 and 2017 in 14 centers in three countries. This study included patients 70 years and older who underwent transcatheter aortic valve replacement or surgical aortic valve replacement. The mini nutritional assessment short form was assessed by trained observers pre procedure with scores seven or less out of 14 being considered to be malnourished. The short performance physical battery was simultaneously assessed to measure physical frailty. The authors found that malnutrition was associated with higher one-year mortality and 30-day adverse events following aortic valve replacement via a transcatheter or surgical approach. While malnutrition and frailty were interrelated, the integration of nutritional assessment resulted in improved predictive value for frail patients. Clinical trials are needed to determine whether pre and post procedural nutritional interventions can improve clinical outcomes in these vulnerable patients.
Do newer generation ultra-thin strut drug-eluding stents improve clinical outcomes over contemporary thicker strut stents? First and corresponding author, Dr Bangalore from New York University's School of Medicine and colleagues search PubMed, Embase and Central and identified 10 trials that randomized more than 11,650 patients and evaluated three newer generation ultra-thin strut drug-eluding stents, that is defined as a strut thickness less than 70 microns, versus thicker strut second generation drug eluding stents and reported clinical outcomes. They found that newer generation ultra-thin strut drug-eluding stents were associated with a 16% reduction in target lesion failure, which was a composite of cardiovascular death, target vessel myocardial infarction or ischemia-driven target lesion revascularization evaluated at one year follow-up. Ultra-thin strut drug-eluding stents reduced the risk of target-lesion failure driven by a reduction in myocardial infarction and also a qualitatively lower rate of stent thrombosis compared to contemporary thicker strut second generation drug-eluding stents.
Ambient air pollutants are known to be associated with increased cardiovascular morbidity and mortality, however, what is the association between air pollution and cardiac structure and function? First and corresponding author Dr Aung from Queen Mary University of London and colleagues performed a cross-sectional analysis of a large population free of preexisting cardiovascular disease in the UK Biobank population study. They found that higher past exposure to fine particulate matter and nitrogen dioxide were associated with larger cardiac biventricular volumes. Proximity to major roads, a surrogate for chronic air pollution exposure, was additionally associated with higher left ventricular mass. These associations between ambient air pollution and at first cardiac phenotypic changes, in individuals without prevalent cardiovascular disease, suggest that air pollution should be recognized as a major modifiable risk factor which needs to be targeted by a public health measures.
The final original paper this week is the first study to demonstrate a causal link between atrial fibrillation and the NLRP3 inflammasome, which is an innate inflammation signaling complex. Co-first authors, Drs Yao and Veleva, corresponding author Dr Li from Baylor College of Medicine and colleagues assessed MLRP3 inflammasome activation by immunoblot in atrial whole tissue lysates and cardiomyocytes from patients with paroxysmal or long-standing persistent atrial fibrillation. They found that NLRP3 inflammasome activity was increased in these patients. To determine whether cardiomyocytes specific activation of NRLP3 was sufficient to promote atrial fibrillation, they established a cardiomyocyte specific knock in mouse model which expressed constitutively active NLRP3. These mice developed spontaneous premature atrial contractions, an inducible atrial fibrillation, which was attenuated by a specific NLRP3 inflammasome inhibitor. Cardiomyocyte-specific knockdown of NRLP3 suppressed atrial fibrillation development in these mice. Thus, these results establish a novel pathophysiological role for cardiomyocyte NLRP3 inflammasome signaling with a mechanistic link to the pathogenesis of atrial fibrillation, and suggests that inhibition of NLRP3 may be a potential novel atrial fibrillation therapy approach.
And that brings us to the end of our summaries.
Now for our feature discussion.
Is pericardiotomy going to be our next treatment for heart failure with preserved ejection fraction or HFpEF? I have the first and corresponding author of a very intriguing research letter. Dr Barry Borlaug from Mayo Clinic in Rochester, Minnesota, joining me today to tell today about his great paper. Barry, welcome back to the show. You are amazing. Congratulations on yet another wonderful publication. So, could you set us up. Those of us who don't think about this every day. The hemodynamics of what pericardiotomy does. Tell us what was the rationale of doing this study?
Dr Barry Borlaug: You know, it's interesting. We think about intracavitary pressures on the left side ventricle and the left atrium causing congestion and pulmonary hypertension. We think that this is all related to left ventricular issues, but about 30 or 40% of the pressure is actually related to external restraint on the heart as mediated by the right ventricle across the septum and the pericardium and external pericardial contact restraints. In animals, we've known since back in the late 1970s, that with the chest open, if you open up the pericardium, which we know in HFpEF, on average, is shifted up and to the left. It's stiffer. This effect really comes into play more at higher heart volumes. It doesn't have as much of an affect at lower heart volumes like might be absorbed with rest. It's even been rumored that in some species like greyhounds, illicit dog racers, would actually cut away the pericardium so these dogs could race better. It's actually been shown that they can experimentally, in a paper in the 1980s, that they can exercise the higher peak VO2. They have a higher cardiac output response, because the heart is better able to utilize the Frank-Starling relationships to augment ventricular filling and ejection at fuller pressures.
Dr Carolyn Lam: Oh my goodness. I didn't know that latter fact about the racing dogs. Could I ask you something? We've talked about this before back in the day. When you say the left side the filling pressures go up when there's pericardial restraint, remember we used to talk about a parallel shift upwards versus true intrinsic stiffening ... diastolic stiffening. You still do mean that parallel shift upwards, right?
Dr Barry Borlaug: That's right. If it was purely an increase in stiffness, we would expect it to sort of rotate, pivot from the bottom left up, but what we see, and in human data, we published a number of years ago, most of the increase in LV end-diastolic pressure is a parallel shift upward in the diastolic pressure volume relationship. That really suggests that there's an increase in restraints on the heart. That's why we think that that's an important target and it's possibly more remediable to treatment since we're having such tough luck changing the viscoelastic properties of the left ventricle, not that we shouldn't be doing that, but this might be something different that we could do that might give us a little bit more of a benefit in terms of filling pressure reduction.
Dr Carolyn Lam: True. True. But the way you describe it too, it does mean that we may be talking about, I hate to say this but, specific subsets or types of HFpEF, where that may play a bigger role and I'd just like to bring the audience to your incredible paper that I think that I've cited a gazillion times already on the obese HFpEF phenotype. Do you want to remind everyone about that because I think there you really [inaudible 00:16:30], didn't you that ventricular interdependence played a big role.
Dr Barry Borlaug: So, in people with obese HFpEF, which is now becoming by far one of the most dominant. Oh God. We did a study that compared them to non-obese and we see that the obese patients have a bit more plasma volume expansion, a bit more cardiac remodeling, right heart enlargements, increase of LV mass and an increase in epicardial fat. What all this does is increases the total heart volume in the pericardial space. Because the pericardium doesn't appear to grow as much as the heart volume, this increases the coupling between the right and left heart. Some people, perhaps like the obese phenotype of HFpEF, might be more poised to derive benefit from approaches to therapeutically remove this excess pericardial restraint.
Dr Carolyn Lam: Okay, now you just have to get down to telling us what you did. This was a first in man pilot study. Drum roll everybody. You gotta listen up. This was so cool.
Dr Barry Borlaug: This physiology just got us thinking that maybe we could do this to help our patients with HFpEF. First we tested this in dogs, then with pigs with features of HFpEF and it seemed to work there so the next step was to show that it might work in people. We took people that were already going to get their pericardium open, so people that were referred for cardiac surgery. We wanted to choose people that had risk factors for HFpEF and diastolic dysfunction but maybe not necessarily diagnosed HFpEF.
Dr Barry Borlaug: We took people who were referred for aortic valve replacement for AS, coronary artery bypass grafting or both and consented them ahead of time, put catheters into them to measure hemodynamics and then we measured resting hemodynamics with the chest open, but pericardium intact, because the changes that we see occur predominantly when there's an increase in volume load to the heart, we then had to stress the system. Now we can't have them exercise cause they're under general anesthesia with an open chest. You achieve that by elevating their legs and giving them a little saline bolus, so we had a pressure at rest, pressure with saline load.
Then we asked our surgeons to open the pericardium, which they do obviously to gain access to the heart for cardiac surgery and we repeated the same assessments and intervention. What we saw was that the resting filling pressures, again these people did have diastolic dysfunction, the resting pulmonary wedge pressure was about 16. With the volume load maneuver, it increased to 25 when the pericardium was intact. After we had opened the pericardium, the increase in wedge pressure, which was our primary endpoint, was reduced from an increase in nine millimeters of mercury down to an increase of only three millimeters of mercury. So that verified our hypothesis that the pericardium contributed and that we could prove total cardiac diastolic reserve, if you will, just by removing that pericardial restraints.
Dr Carolyn Lam: Wow. I love the figures, by the way, that you've drawn as always they illustrate that so beautifully. And listeners, this is a research letter, so there's that one central figure that you must get your hands on right away. Now Barry, I think the first question is this wasn't really HFpEF patients right? Let's be very clear with the audience who these were though and then you did a subset analyses though, a further analysis that showed this may apply more to people with higher wedge at rest. Could you elaborate?
Dr Barry Borlaug: Absolutely. While these people, and Carolyn, I think you know as well, I think a lot of people probably have HFpEF that they have a sort of occult HFpEF, that's not been diagnosed maybe because unfortunately, not everybody else thinks about this diagnosis. When you look at the charts very carefully, and found out about 13 of the 19 patients complained of significant dyspnea based on chart review. Of those 13, 10 had other indicators that according to current criteria would give them the diagnosis. When we looked at this at this very post hoc, sort of exploratory subset, we actually saw that these patients, even though they didn't necessarily have a clinic diagnosis of HFpEF, that these patients actually responded even more favorably to the effects of pericardiotomy in their greater reduction in the increase in wedge pressure. When we plotted in the figure that you mentioned, we plotted the change in the increase in wedge pressure, it was really the patients that had the greatest increase with volume loading initially that derived the most benefit. That makes sense because those were the people where the pericardium and the restraint is the becoming most operative, when the heart is most distended and congested.
Dr Carolyn Lam Maybe one quick last question. What next Dr Borlaug? Gosh, you just keep coming up with one thing after another with the animals. I noticed that it was a non-invasive pericardiotomy. I'm reading between the lines here. What are you going to do next? Do you think this is ready for prime time?
Dr Barry Borlaug: As usual, you're reading correctly between the lines. We have filed a patent awhile back for this and we have a device that can achieve a pericardial modification or an anterior pericardiotomy without the need for open heart surgery, so that you don't crack the sternum. It's done from a subxiphoid approach and we've actually just received some funding to start doing this under an IDE, which we will need to work with the FDA. We hope to do and start testing this in patients that have HFpEF and then look at the acute hemodynamically affects. Then we'll also begin to explore the safety and potential efficacy using other indices like imaging, exercise capacity and things like that.
Dr Carolyn Lam: That is just so cool. I think that one of the immediate take home messages for me now though is when we see patients who we think have HFpEF, have a low threshold to look for evidence of constriction. I would say that we may miss the diagnosis of people who legitimately have constrictive pericarditis and may need to benefit from this. I think it's one of those hidden diagnosis, so that's one thing. And then the next thing, if I could just ask you, are there any patient populations that you say should not undergo this? And I say this because I remember back in the day again, when we were experimenting with dog models, this is just gestalt okay, but I thought that the dogs who had right-sided heart failure, severe right-sided heart failure, needed that pericardium to lean on, and if you released it, the dilatation on the right side would just be inexorable because there is no pericardium to rein them in. Do you get what I mean? I don't know. I'm just curious if you have any patient population right now that you're already thinking I'm not going to include in my trial.
Dr Barry Borlaug: Yeah. That's a very important point, Carolyn. We would not want to apply or test initially certainly this therapy where eccentric cardiac remodeling is a problem because we know that there is a little bit of eccentric dilatation even in people after a regular cardiac surgery with pericardiotomy. Marty Molenter showed that, in a paper back in the 1980s, you have a patient who already has some dysfunction, we would hypothesize that they may get a bit worse, so we would not want to test this in people with the right ventricular dysfunction, right ventricular enlargement phenotype of HFpEF. We would not want to give this to people with HFrEF. Remember with HFrEF, we wanted to do just the opposite. We tested this years ago with the ACORN trial or older studies wrapping the latissimus dorsi around the heart to cause reverse remodeling so this is really something that would maybe work more for people with smaller stiff hearts, HFpEF, where that concern that they're going to dilate and get low EF heart failure either on the left or on the right side. We would want to focus more on the small hearts and away from those people with dilation.
Dr Carolyn Lam: That is so great. Thanks so much Barry for letting us under the hood. Congratulations once again. These are just great papers. Keep them coming. Well listeners. I'm sure you enjoyed that as much as I did. Don't forget to tune in again next week.
James de Lemos: Welcome everyone to Circulation on the Run my name is James de Lemos, I am the executive editor for Circulation based at UT Southwestern in Dallas and I will be filling in for Carolyn today as we discuss this year's surgery themed issue. I would like to welcome Dr Marc Ruel, the chairman of cardiac surgery at the University of Ottawa and a long-time editor of the Circulation of surgery themed issue, as well as Dr Tim Gardner, professor of cardiac surgery at The University of Pennsylvania and our leader at Circulation on the editor team for issues related to cardiac and vascular surgery. Marc and Tim, welcome and thanks for all your tremendous work in this issue.
Dr Marc Ruel: Thanks James for having us.
Dr Tim Gardner: Thank you. Glad to be here.
James de Lemos: Why don't we start Marc with your thoughts on how this issue comes together, how it came to be, you picked the papers and how we ended up with this terrific issue.
Dr Marc Ruel: It’s been a really important year for surgery and for this issue, as some of you may know the supplement which used to be the old designation of this issue has been changed to the surgery themed issue in about 2014 or so where the new Circulation leadership and what we tried to do every year is to bring the very best, not only of cardiovascular surgical science but also of clinical care and pearls around clinical and surgical care. So, I think this year we have had probably more than 60 submissions sent to us. Tim and I have looked at those very closely and you as well, James, we really wanted to get the feedback and the approach from not only cardiac surgeons but also from cardiologists and cardio vascular care specialist around those. We've tried to select the best of science and also some papers that we feel would be very useful with regards to providing new clinical pearls for surgeons and anyone in the circle of care around cardiovascular surgery.
Dr Tim Gardner: If I could just add, James, of course we have other papers that have been submitted by surgeons that are published or that deal with cardiac surgical or vascular surgical topics during the year, this particular issue is very much focused on cardiac surgery but throughout the year we have plenty of submissions of manuscripts by surgeons about surgery about surgically related topics and so on. So, I am actually kept quite busy reviewing and commenting and consulting on manuscript submissions of Circulation. There are plenty of papers over the course of the year that relate to surgical topics.
James de Lemos: Wonderful, I think you will see, as we talk about these papers, really that what Marc and Tim are talking about in terms of papers that are broadly relevant to cardiac surgeons and cardio vascular providers really rings true. Let’s walk through the issue, its set up like most of our issues begins with a couple of opinion pieces, a brief frame of reference, articles about important topics. Marc, do you want to talk about the Domanski paper, talk about revascularization for ischemic cardiomyopathy?
Dr Marc Ruel: Absolutely, we've asked experts, namely Mike Farkouh and Micheal Domanski, to provide us where their thoughts regarding the optimal treatment on patients with LV dysfunction and severe coronary disease. What many of us would call an ischemic cardiomyopathy, which may be construed as a misnomer or as an accurate term, I will not debate on this today, but certainly it remains a very vexing clinical problem. I think we could all agree that the last niche where we still see very high in terms of treatment for coronary disease this is probably mortality and kind of an inability to provide for a tangible result.
Once LV dysfunction has set in and the present of CAD the outcomes are poor, and it took years and literally almost ten years for the STICHES trials to show a benefit for surgical treatment. This is relatively all study now and it has to be put in context and I then that Mike and Mike are doing this extremely well in terms of providing the caveat, for instance, STICHES at its inception added had a 5% mortality rate around CABG, so we know that the modern outcome are probably better than that. It’s very difficult to actually decipher what sound be the mainstay of treatment for each challenging patient and I think the frame of reference provided by Dr Farkouh and Domanski is extremely useful in helping with that.
James de Lemos: Tim we have another frame of reference that is also provocative. Trying to make a case that we think about in patients with hypertrophic cardiomyopathy with obstruction early surgical procedures to relieve the obstruction. Do you want to tell the readers a little bit about this opinion piece and what your thoughts on it are?
Dr Tim Gardner: Sure James, this is a really nice frame of reference article from both doctors Martin and Barry Maron and then their European contributor Paolo Spirito and the point of their opinion paper is that the surgical art for managing this very difficult obstructive cardiomyopathy syndrome has reached the point where we really shouldn't wait until patients are in extremist or in class 3 or 4 status in term of syndromic problems and can consider earlier surgery for these patients. They make the very important point which I think we have to except is that for patients to do well with this operation they need to be in a center where there is experienced surgery and experienced surgeons, but the point is now that the state of the art for managing obstructive cardiomyopathy is as such that good result are obtained and patients should be offered this surgery when appropriate, but earlier, in order to avoid the challenges of end stage cardiomyopathy and difficulty relieving the obstruction, so this is a really important opinion piece. It’s great to see our cardiology colleagues who are experts in this field make this point based on well published data from centers like the Mayo Clinic.
James de Lemos: Moving now to the original articles, we've got 5 original articles, maybe Marc we can start with your thoughts on 2 articles related to revascularization, one in coronary disease and one identifying a really novel approach for treating type A aortic dissection with malperfusion.
Dr Marc Ruel: I think that's well said James, the first of these original papers will be likely somewhat controversial. The first author is Dr Bo Yang and essentially it is a series from Michigan where they look at just shy of 600 patients with acute Type A Aortic Dissection, of whom 135 were identified to have malperfusion syndrome. Essentially defined by the authors as something slightly different than malperfusion per say but really malperfusion accompanied with evidence of necrosis in one of the organs.
Their approach has been new and somewhat controversial in that they have brought these patients first to the interventional radiology suite in order to fenestrate in many cases or at least open the culprit artery or the culprit perfusion territory that leads to malperfusion syndrome and then depending on how the patient is doing they would then proceed to open repair as soon as 24 hours afterwards or they may wait longer in someone where there is no sign of improvement yet prior to moving to the ER, so they have found this has not only improved the results with regards to in hospital mortality after operative repair type A aortic dissection, but also to allow them to better discern or differentiate should I say between patients in whom malperfusion may lead to a futile situation and who then may be avoided from undergoing a very complex and difficult OR so would argue this is probably the first such large organized, well documented series of such an approach and I think it will lead to some head scratching, this being said it must be remembered that the goal standard for Type A aortic dissection is dealing with the intrapericardial aorta first and hoping that the perfusion gets better from this and everyone knows that the results of this approach are not fantastic.
We know that even in the best centers, including the latest data from Germany such an approach has about a 20% mortality rate so clearly there are ways that we can improve with Type A aortic dissection and this paper may be a strike in the right direction.
James de Lemos: The other revascularization paper addresses that, I would say also a quite controversial topic which is how many atrial grafts are optimal in patients that are undergoing surgical revascularization?
Dr Marc Ruel: This is a paper from Toronto where the Ontario ICES database was used and several papers actually dozens and dozens of papers have come out previously from this well established and well allocated database. Steve Fremes who is the senior author and one of his trainees, Dr Rocha and the team of authors got together and decided to look at the impact of 3 versus 2 arterial grafts in patients undergoing cabbage with regards to survival. They have very nice, very compelling follow up information and they basically carry out 2 exercises.
First, they wanted to see if the 3,000 patients or so had 3 or more arterial grafts had a better outcome than the 8,000 patients or so who had 2 arterial grafts and frankly they found there was no significant difference with regards to survival at 8 years and freedom from MACCE at 8 years. However, when they compare those 9 or 8,000 patients or so who had 2 arterial grafts to the rest of 40,000 or so patients who had 1 arterial graft and completions with veins they found that again there was a survival benefit. This last finding is not new and its obviously subject to indication biases as well as expertise bias as we've seen in many of the observational perspectives studies around multiple arterial grafting. But I think the concept of comparing 2 versus 3 arterial grafts is very novel in surely in this paper is being addresses with very high scientific related from the numbers and the quality of the follow up that's been brought to the exercise.
James de Lemos: I've really been struggling, I love your thoughts and Tim, your thoughts on how to reconcile the data in space. I really am having a hard time getting my head around what seems to be conflicting data about the number of arterial grafts in what an optimal CABG looks like in 2018 with the evidence that we have. What are your thoughts on that question?
Dr Tim Gardner: I think that this supports the concept that 2 arterial grafts whenever possible for some patients, younger patients perhaps 3 but I think the important point is, multiple arterial grafting should be attempted and carried out whenever possible. I leave the is 3 better than 2 to some future study or future review that can be more precise about that.
Dr Marc Ruel: This being said I think we don't view efficiently coronary surgery as being an area of expertise and many centers including very strong academic centers may not necessarily marry the concept that coronary surgery has to be something with the dedicated expertise. I think when we look at those observational perspectives series we see the effect of it may be the expertise bias, but it may be more than just 2 or 3 arterial grafts, they may be the whole wrapping of care that comes with it including optimizing beta blockers and managing diabetes etc. So, I think it may be more than purely conduits but definitely, as Tim said, 2 arterial grafts are probably better than just 1 and the jury is still out on whether 3 is better than 2.
James de Lemos: Excellent. Switching gears now Tim, an area that obviously you have tremendous experience and expertise we've got 2 innovative papers addressing surgery for individuals who have congenital heart disease. Can you update us on what we are publishing here?
Dr Tim Gardner: Sure, the one study focuses on the risks of pulmonary valve surgery in adult patients who underwent a correction of tetralogy of Fallot earlier in life. This is a growing population actually we refer to as young adult with congenital heart disease and in many centers they are more numerous in terms of the patients groups than infants because this group has been successfully treated early in life, but this particular group of patients, patients who have had tetralogy of Fallot repaired and end up with what the author calls right ventricular outflow disfunction generally regurgitation through the outflow tract pulmonary valve sometimes obstruction, these patients then face significant clinical challenges in death from heart failure, right ventricular failure or arrhythmias in their late 20's and 30's. We have been focusing now on the timing and the type of pulmonary valve replacement.
Dr Tim Gardner: Now there is catheter replacement options available, but when to do this and how to minimize risk is really the focus of this one paper that describes a four multi-center study looking at predictors of risk for these patients. Sort of a hypothesis generating paper, but it is an important study none the less, focusing on how to identify patients with right ventricular out flow tract dysfunction and who should have pulmonary valve replacement and when that should optimally be done. It a very good study. The other important study that we have is that the other age spectrum of neonates and this is a study that is based on a review of data from the pediatrics heart health information systems database, led by the group at the Children's Hospital Philadelphia.
Looking at variations in pre-operative care and management of neonates with transposition of the great arteries. This was a little controversial actually when we reviewed it among the editors because the suggestion is that earlier surgery this would be in the first week of life and more perhaps aggressive use of atrial balloon septostomy seems to improve outcomes. This is a generally low risk population, the point of the paper is that these pretty good results can be improved by paying more attention to the timing of surgery and the appropriate use of balloon septostomy. It’s sort of a quality improvement perspective based on a large database and I think it’s a very nice study and undoubtedly creates additional attention to this particular area.
James de Lemos: Marc, our last original paper is a really novel issue engineering approach to creating vascular conduits, can you tell the readers briefly what happens to her in this paper?
Dr Marc Ruel: Indeed. It’s a paper from Stanford, from Joe Woo’s lab and the first author is Daniel von Bornstädt. Essentially, as you say it’s a very innovative novel approach to try to recreate a bioengineered blood vessel. We surely know there's quite a need for such off the shelf conduits, not only in cardiac surgery but also in vascular and vascular surgery and even for things such as AV fistulas and others. It’s really interesting to see that this is what I would call transitional science at its best and surgeons have had an important role over, as you know, centuries in helping develop this and many discoveries have come from surgical labs, especially a few decades ago.
In any case, what Joe and his team have performed is to try to use clinically applicable methods to derive and create a bioengineered blood vessel and they started first with human aortic smooth muscles cells and skin fibroblasts which are literally easy to get and they used those to constructs bi-level cell sheets, they then used a 22 gauge angiocath needle so that the sheets would be wrapped around this in order to lead to a tubular vessel construct. Then the next problem has been traditionally that those bioengineered vessels would burst out with atrial pressure. What Joe's team came up with is to use a commercially available adhesive, so a glue essentially, which is dermabond which typically we use after any form of surgery to keep the incision together and they put dermabond on the surface of this sheet wrapped around an angiocath needle to act as a temporary external scaffold. They then led this into a bioreactor and implanted it in series of 20 rats as a femoral artery interposition graft. The results were excellent. Essentially, patency was perfect and there was a full vascular maturity with all 3 layers of blood vessel that you would expect including an intima that had been formed as a result of the experiment.
I think this is all very promising because none of the methods here are involving something that would have non-autologous issues, or you could easily see this being used with a patient’s own cells in order to achieve an autologous. I think this is obviously small vessels, there are 22-gauge needle is not a big conduit, you’re not going to bypass an LED with this, but I think it’s a start and it’s all done using transitional or clinically applicable methods. I guess the next step would be moving to a large animal model and certainly I think we should stay tuned to see where this leads us.
James de Lemos: I think that's exactly my thinking as well about that discussion and really leads us into some of the issues that come up in the review paper that you are a co-author on new strategies for surgical revascularization. I think this basic in translational science piece is designed to address some of the limitations of current revascularization and you all did a really beautiful job covering some new more clinically ready strategies in your papers. Can you just tell us very briefly what you all covered in that review paper?
Dr Marc Ruel: Indeed, this is a paper that was kind of aiming at being a state of the art around CABG and rapidly the focus was reshaped towards kind of new strategies around surgical myocardial revascularization. Initially we have a section on OPCAB on this and that and minimizing the inflammatory effects of the pump and quickly it became apparent that the desire of Circulation and this themed issue was to focus it more on really what are the up and coming improvements around surgical coronary revascularization. This paper focuses on essentially 4 main areas. One is hybrid coronary revascularization, the second one is less invasive coronary surgery, the third one is the use of multiple arterial grafts to which we eluded a little earlier during this podcast and fourth is the use of an aortic coronary surgery, essentially meaning bypass surgery performed without any manipulation of the aorta.
James de Lemos: As we think about innovation in terms of conduits, the procedure itself, the other aspect that's covered in our last paper is can we make the procedure safer perhaps by modifying our use of anti-platelet therapies based on meshment of the platelet phenotype and Tim do you want to bring us home by just telling us a little bit about what we learned from Paul Gurbel and his group of platelet experts?
Dr Tim Gardner: Well we learnt a lot about platelet science and appropriately so Dr Gurbel is a well-recognized expert in platelet physiology or platelet management and this is a really quite a challenging area because many of our patents come to surgery especially for coronary surgery already on platelet inhibitor agents and what Dr Gurbel and his co-authors showed in this paper is that although there is somewhat limited data there can be and should be platelet function testing and with an appropriate understanding of platelet inhibition drugs that we may be able to limit the time between removal of these or discontinuation of these platelet inhibitor drugs and the necessary surgery which will improve outcomes and reduce bleeding in patients requiring urgent CABG surgery. It’s a very useful update and it is a good example of a paper that isn't written by surgeons, but really applies very much to the cardiac surgical treatment of coronary artery disease
James de Lemos: I really like the very practical tables and figures that lay out the potential tests that surgeons or anesthesiologists may consider for assessing this and even how one might implement. I would like to bring us to conclusion now, first I want to acknowledge, Sara O'Brien at the Circulation office for her amazing work together with Marc and Tim pulling this issue together, making sure that we have a consistent high quality issue with wonderful figures and tables and it really came together beautifully and thank you both for joining me today and the podcast I think it’s obvious that we've got an issue that all of you listen to this podcast need to actually pull out the issue or download it because we have a co-host of wonderful papers to look at and cardiac surgery thriving at Circulation. As we've talked about this is the tip of the iceberg, this themed issue, we've got great content coming, issue after issue. We are already open for business next year’s issue, so please send us your best cardiac surgery research. Please pay attention to these important papers and apply them in your practice because I think many of them are already directly applicable.
Marc given your leadership role in the issue do you want to bring us home and make any concluding remarks?
Dr Marc Ruel: I think your points are very well taken James and I want to reintegrate that if I speak on behalf of the cardiovascular surgical community, we are very thankful to the leadership with Circulation. James, Joe, Tim and many others and obviously the support from the staff in clearly establishing that cardiovascular surgery is a very important therapeutic mentality and the overall scope in the broad scope of cardiovascular therapeutics.
Dr Carolyn Lam: You've been listening to Circulation on the Run. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. This week's issue provides much long awaited healthcare resource utilization and cost implications in the MOMENTUM 3 randomized controlled trial of a magnetically levitated cardiac pump in advanced heart failure. All of this coming right up after these summaries.
The first original paper this week provides important mammalian data on the acute effects of phosphodiesterase type 1 inhibition on the heart. Now phosphodiesterase type 1, or PDE1, is known to hydrolyze cyclic AMP and cyclic GMP in the heart. However, what's important to understand is that data from rodents may not be applicable to humans because rodents express mostly the cyclic GMP favoring PDE1A isoform, whereas human hearts predominantly express PDE1C isoform which has a balanced selectivity for cyclic AMP and cyclic GMP.
In today's paper, first author Dr Hashimoto, corresponding author Dr Kass from Johns Hopkins University School of Medicine and colleagues, determined the acute effects of PDE1 inhibition on PDE1C expressing mammals, dogs and rabbits, in normal and failing hearts. They found that selective inhibition of PDE1 with ITI-214 induced positive inotropic, lusitropic, chronotropic, and arterial vasodilatory effects in dogs and rabbits. These effects occurred via cyclic AMP modulation and were observed in failing hearts. ITI-214 contractile increase was insensitive to beta adrenergic blockade or heart rate increase, but inhibited in vivo by adenosine receptor inhibition. Furthermore, isolated myocytes revealed differences between PDE1 and PDE3 inhibition. Wherein PDE3 inhibition, augmented beta receptor agonism and calcium transients, whereas PDE1 inhibition enhanced function without calcium increase. These findings have important clinical implications for ITI-214 which has completed phase 1 trials and may provide a novel therapy for heart failure.
We know that macrophages are involved in foam cell formation in atherosclerotic plaques, but our next paper tells us we may now have a way to therapeutically modify this. Co-corresponding authors Dr Wei and Schober from Ludwig Maximilian's University Munich elucidated the role of microRNA generating enzyme Dicer in macrophage activation during atherosclerosis. They showed that Dicer deletion in macrophages accelerated atherosclerosis in mice, along with enhanced inflammatory response and increased lipid accumulation in lesional macrophages. In vitro, alternative activation was limited, whereas lipid filled foam cell formation was exacerbated in Dicer deficient macrophages due to impaired mitochondrial fatty acid oxidative metabolism. MicroRNA biogenesis promoted the degradation of fatty acids by mitochondrial respiration in macrophages, which in turn reduced intracellular lipid storage and limited atherosclerosis. Thus, reducing foam cell formation in atherosclerotic arteries by enhancing energy metabolism through microRNA mediated fatty acid oxidation may be a promising approach for the treatment of atherosclerosis.
The next study evaluates how aortic stiffening relates to resting cerebral blood flow and cerebral vascular reactivity in older adults. First and corresponding author Dr Jefferson from Vanderbilt Memory and Alzheimer's Center and her colleagues studied participants free of clinical dementia, stroke, or heart failure, including 155 older adults with normal cognition and 115 mild cognitive impairment. They found that greater thoracic aortic stiffening quantified by cardiac magnetic resonance was associated with lower cerebral blood flow in cognitively normal older adults. Aortic stiffening was associated with reduced resting cerebral blood flow in the presence of preserved reactivity and associated vasodilatory capacity, particularly among participants without hypertension. ApoE4, a well-known genetic susceptibility risk factor for Alzheimer's disease, modified the results with stronger effects among carriers in the temporal lobes, where Alzheimer's disease pathology is known to first evolve. In summary, greater aortic stiffening related to lower regional cerebral blood flow and higher cerebral vascular reactivity in cognitively normal older adults, especially among individuals with increased genetic predisposition for Alzheimer's disease. Understanding the association between higher aortic stiffness and compromised brain health, including cerebral hemodynamics, may allow for earlier detection and targeted interventions to prevent or mitigate the onset of more serious cerebral vascular damage associated with greater aortic stiffening.
Aortic valve replacement for aortic stenosis is usually timed according to the development of symptoms, but could the timing be too late once irreversible myocardial scar has developed? Co-first authors Drs Musa and Treibel, corresponding author Dr Greenwood from University of Leeds and their colleagues found that in patients with severe aortic stenosis, focal myocardial fibrosis determined by cardiac magnetic resonance imaging was present in over 50% of patients and was associated with a two-fold higher late mortality. Focal scar was independently associated with all cause and cardiovascular mortality, after both surgical and transcatheter aortic valve replacement. In severe aortic stenosis, late gadolinium enhancement appears to be a useful biomarker of left ventricular remodeling, and its presence is associated with worse long-term outcomes following aortic valve intervention. Thus, in severe aortic stenosis, late gadolinium enhancement may be a useful biomarker of left ventricular remodeling, and its presence may be associated with worse long-term outcomes following aortic valve intervention.
The next study suggests that endogenous factor Xa activity may be irrelevant pharmacodynamic marker to guide Edoxaban dosing in future. First author Dr Yin, corresponding author Dr Giugliano from TIMI Study Group, Brigham and Women's Hospital in Boston, and their colleagues, describe the value of endogenous factor Xa activity as a pharmacodynamic marker, linking Edoxaban concentrations and clinical outcomes in the ENGAGE AF-TIMI 48 trial. They showed that the extent of inhibition of endogenous factor Xa activity was influenced by Edoxaban dosing and clinical characteristics, and was associated with both antithrombotic benefit and risk of bleeding. The implications are that this approach of linking endogenous factor Xa activity to clinical outcomes may be used to guide dose selection in future clinical trials, to monitor patients in certain clinical scenarios, or to define the doses of oral factor Xa inhibitors in patients who require precise anticoagulation therapy.
The next paper describes a novel multi-protein complex that plays a critical role in regulating cardiomyocyte survival. First author Dr Zhang, corresponding author Dr Yan from University of Rochester School of Medicine and Dentistry and colleagues, showed that phosphodiesterase 1C is activated by transient receptor potential canonical channel-3 derived calcium, thereby antagonizing adenosine A2 receptor cyclic GMP signaling and promoting cardiomyocyte death or apoptosis. Targeting these molecules individually, or in combination, may represent a compelling therapeutic strategy for potentiating cardiomyocyte survival.
The final paper demonstrates a molecular link between two well-recognized biomarkers of fibrosis, Galectin-3 and Osteopontin. First author Dr Shirakawa, corresponding author Dr Sano from Keio University School of Medicine and their colleagues, showed that Osteopontin was almost exclusively produced by Galectin-3 high CD206 positive macrophages, which specifically appear in the infarct myocardium after a myocardial infarct. The interleukin-10-STAT3 Galectin-3 axis was essential for Osteopontin producing reparative macrophage polarization after myocardial infarction, and these macrophages contributed to tissue repair by promoting fibrosis and clearance of apoptotic cells. These results therefore suggest that Galectin-3 may contribute to reparative fibrosis in the infarct myocardium by controlling Osteopontin levels. And that brings us to the end of this week's summaries, now for a feature discussion.
Left ventricular assist devices have truly revolutionized our management of advanced heart failure. In fact, these devices have allowed us to keep patients not just as a bridge to transplantation, but as destination therapy. The devices get better and better but also more and more expensive, and the problem is, that places a lot of strain on our healthcare systems. A lot of us are crying out for information on the cost effectiveness of these newer devices, and guess what? We have answers this week with our featured paper.
I am delighted to have with us the first and corresponding author Dr Mandeep Mehra from Brigham and Women's Hospital in Boston, Massachusetts, as well as our senior editor Dr Biykem Bozkurt from Baylor College of Medicine in Houston, Texas. Hello, Mandeep and Biykem! I am so pleased to be talking about a subject really close to all our hearts. Mandeep, could you start by maybe sketching out the actual issue, and maybe reminding our audience what's the difference between the different types of left ventricular assist systems that you compared.
Dr Mandeep Mehra: The era of left ventricular assist devices took a major therapeutic shift when we recognized that we could usher in continuous flow devices. These are devices that generate no peripheral pulse, they do not have systole and diastole. And these devices are small in profile, have very few moving parts, and there are several commercially available devices, two in the United States and up to three worldwide, that bear these characteristics.
The HeartMate II device, which is a continuous flow device that flows blood in an axial format. The HeartWare, or HVAD device, which is a centrifugal flow pump, where the blood comes in and then is ejected at a 90 degree angle. The Jarvik 2000 pump that is still used in some areas, in many regions experimentally, and then the new kid on the block, the HeartMate 3 device, which is a centrifugal flow pump with some very unique technological characteristics.
Dr Carolyn Lam: Nice! And now drumroll, please tell us what you found in your brilliant study this week.
Dr Mandeep Mehra: First, I'd like to remind the audience that the MOMENTUM 3 trial which randomized patients to the HeartMate II versus the HeartMate 3 device, was called MOMENTUM 3 and was a two-year study. We presented the pivotal two year trials results in 366 randomized patients earlier this year in The New England Journal of Medicine, and this study showed that the HeartMate 3 was superior on the primary endpoint when compared to the HeartMate II. The primary endpoint was survival, free of a disabling stroke, or the need to replace the pump surgically for a pump malfunction. And much of that, Carolyn, was driven by the need for replacement of the pump because the HeartMate 3 pump has some unique features that reduce its proclivity for pump thrombosis.
The HeartMate 3 pump is a frictionless pump. It's completely, magnetically, dynamically, born in the rotor. It has wider blood flow paths, so we don't see hemolysis with this pump. And this pump also has an artificial intrinsic pulse that has been created, that pulsates the pump in a 40 beats per minute configuration. So this was the primary trial result, and one of the lucky foresights that we had when we designed the trial was to embed, prospectively, economic analysis within this trial. We recognized that the cost effectiveness related issues and cost configurations with these devices would become very, very important as we scale into today's day and age of healthcare transformation. And the paper that is being presented in Circulation this week, really speaks to the health resource utilization and cost outcomes between the two devices.
We found that the HeartMate 3 pump is actually a cost minimization device, and what that means, Carolyn, is that we have become very used to thinking of new technology as providing incremental costs. So we think that, "Oh, well, what incremental costs should society bear for the benefits as we allocate new technology?" And in this particular trial, what we found is that while the costs of the pump itself, the HeartMate II and the HeartMate 3, were kept the same, which means its operational implant costs were the same, pretty much. We found that the HeartMate 3 pump was associated with a reduction in healthcare resource utilization over two years and with a marked decrease in cost. And in fact, our estimate of cost reduction was in the range of about 65 thousand dollars less, compared to the HeartMate II, in favor of the HeartMate 3.
Dr Carolyn Lam: Wow, Mandeep, first of all, congratulations on these remarkable findings. Biykem, I really have to bring you in here. What do you think of the implications of this?
Dr Biykem Bozkurt: First, I would like to congratulate the authors for a very innovative approach. As Mandeep has stated, they prospectively collected very challenging billing data from the hospitals, and then also did a very complex analysis including the VRG, as well as looking at payer reimbursements for public versus private. And did a variety of subgroup analysis, which I thought was quite helpful in sorting out that perhaps the cost effectiveness was concurrent both from the Medicare, the public, as well as the private, or regardless of the intent for destination versus bridge to transplant.
Probably the most important concept when you look at these close analysis is incremental cost effectiveness ratio, per quality of adjusted life year gained. Now, I do realize the current analysis doesn't allow us to infer the ICER benefit or the incremental cost effectiveness, which I think the investigators are planning to do with a thousand and more patients over a course of two years, which is going to be probably the more definitive. But as it currently stands, with what is provided by Dr Mehra and his colleagues is, we're probably reaching that sweet spot of what is construed as the cost effectiveness ratio of a cost.
Let's say 100 thousand dollars over the course of a year, then I would like to ask Mandeep whether on the prediction will reach that threshold of less than 100 thousand dollars. Because the former studies, looking at the ICER ratios, or incremental cost effectiveness ratios for the DT destination therapies, usually we select somewhere around 200 thousand dollars. And I know that usually that is seen as a prohibited cost, and there was a discussion whether we would be able to reduce the cost by about half, either doing index admission and add subsequent hospitalizations. With the data Dr Mehra and his colleagues have shown, it looks like the re-hospitalization cost is about, approximately half, or reduced by 50%. Mandeep, any thoughts on that, on that sweet spot?
Dr Mandeep Mehra: Yeah. I think, Biykem, you have articulated this extraordinarily well. And for the audience, since it's worldwide, I'd like to place a few things in perspective on how to think of economic modeling. First of all, the point I would make is that this is the first prospectively collected data that we have in the field, and as you pointed out, it was very, very difficult to pull this data together and is still very complex. But let's just think about what ICER really is. It all starts with what we consider to be health utility.
For example, Carolyn, Biykem, and me less so, would have a health utility of 1.0, 1.0 means a perfect health utility number. And I know, Carolyn, you and Biykem are absolutely perfect so you would be a 1.0, I probably am not a 1.0. But a patient with advanced heart failure has a health utility of about .4, so that's only 40% of what is perfect. And when we place ventricular assist devices, whether you place the HeartMate 3 or the HeartMate II, the health utility actually jumps up to about .7. So it's not perfect yet, but it moves all the way up there.
The incremental cost effectiveness ratios of implanting a device over time are calculated based on this health utility benefit, compared to the population of advanced heart failure. And the best current estimates of the HeartMate II are that ICER is about 200 thousand dollars, per quality adjusted life years gained, and this has been done by creating what's known as Markov modeling. A lot of that, by the way, is conjecture, it's not real information. It is predicted information, so one has to take that data with a grain of salt.
Here in this health resource analysis for MOMENTUM 3, we actually looked at actual data. There are some estimates used in this analysis as well, where we did not have accurate billing forms available, but we focused on those things where we had very clear knowledge of the cost of outcomes. For example, we did not look at the costs of outpatient follow-up care. We mainly looked at the cost differences of hospitalizations. And what we essentially found here is that just looking at hospitalizations and differences between the two devices, the cost differential, whether it's Medicare which is public [inaudible 00:20:14], or whether it's commercial. It ranges somewhere between 50 to 65 thousand dollars of difference between the two devices.
Now, if you assume that the ICER for the HeartMate II is accurately at about 200 thousand, and you reduce that ICER by about 50 to 60 thousand, the ICER would naturally come into the range of what you would consider to be about 135 thousand to 150 thousand dollars per quality adjusted life years gained for the HeartMate 3, compared to an advanced heart failure population. Once we look at it from that perspective, as Biykem pointed out, we are getting closer and closer to the societal norms.
At one time-point, society used to think of a quality adjusted life years gained cost of 50 thousand dollars as something that would be acceptable to society, and this was seemingly based on the threshold for what dialysis provides in benefit. And now, we recognize that we have to really expand that to somewhere around 100 thousand more logically, or between 100 and 150 thousand for some technologies. The important thing I would say to you is that, that is society dependent. So what the United States considers to be a reasonable ICER, say 100 to 130 thousand dollars per quality adjusted life years gained, may not be the same that Great Britain would look at, or Sweden would look at, or another country would look at. And each country actually creates their own economic value propositions, and this will have to be taken into account as we think about this data as well.
Dr Carolyn Lam: How cleverly and clearly articulated, thank you so much Mandeep. Just one last question for both you and Biykem, what do you think this implies for moving to less and less advanced heart failure with these left ventricular assist device systems? Biykem?
Dr Biykem Bozkurt: It's an ever-expanding field, and as these devices are becoming smaller, lower profile with lesser complications and more affordable, probably the utilization will likely increase as we have been seeing. As you know, even the percutaneous non-durable device used, as well as our mechanical circulatory support durable devices are definitely increasing utilization. And thus, one may wonder not only the bridge to transplantation, but the destination therapy portfolio, or bridge to decision portfolio, may really increase as these devices become safer and more affordable.
Dr Carolyn Lam: Wow, that's amazing. How about you, Mandeep, what do you think?
Dr Mandeep Mehra: Carolyn, I couldn't have said it any better than what Biykem articulated. I do think that at least in the United States, as we reach the thresholds of cost effectiveness that we as a society accept, we will start to see a lot more widespread utilization, particularly for lifelong therapy or so-called destination therapy. I completely agree with that. I think that moving the needle to the less sicker population is still challenging, because there are complications with these devices that make that slightly difficult.
There was a trial called the REVIVE-IT trial that was stopped midstream largely because of concerns about pump thrombosis, and that trial was looking at taking these devices to a less sick NYHA class 3 population and was stopped midstream. Now that the HeartMate 3 has pretty much resolved the issue of pump thrombosis, and even show a halfing in stroke rates with this device over two years, I think that that portfolio of evidence needs to be reopened. I would caution though, that until we have confirmatory randomized data in those less sick populations, the use to that population should still stay restricted.
Dr Carolyn Lam: I don't think anyone could have said it better than both of you. Thank you so much for this very insightful and balanced conversation.
Thank you so much for listening today. You were listening to Circulation on the Run, and don't forget to tune again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors.
I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. The ORBITA Trial of percutaneous coronary intervention and stable single vessel coronary artery disease has to be one of the most hotly discussed in the cardiology world. The featured paper of this week adds important knowledge that will help us understand the physiology stratified results of ORBITA.
Coming right up after these summaries.
The first original paper this week provides novel mechanistic insights that may lead to a new treatment approach for obesity and hypertriglyceridemia. Co-corresponding authors, Drs Xiang and Xia from Central South University of Xiangya in China, looked at Reticulin 3, which is an endoplasmic reticular protein that has previously shown to play a role in neurodegenerative diseases.
In the current paper, the authors show that over-expression of Reticulin 3 in mice induced obesity and a greater accumulation of triglycerides. Remarkably, increased Reticulin 3 expression was also found in patients with obesity and hypertriglyceridemia. They further showed that Reticulin 3 played critical roles in regulating the biosynthesis and storage of triglycerides and in controlling lipid droplet expansion. Thus, these results suggest that inhibiting the expression of Reticulin 3 in fat tissue may be a novel therapeutic approach to treat obesity and hypertriglyceridemia in the future.
The next study provides insights into the genetic determinates of residual cardiovascular risk in patients already receiving statins. First author Dr Wei, corresponding Dr Denny from Vanderbilt University Medical Center and their colleagues performed a genome-wide association study and identified that a variation at the LPA Locus was associated with coronary heart disease events during statin therapy and independent of the extent of LDL cholesterol lowering. The association of the LPA Locus with coronary heart disease events persisted in individuals with an LDL cholesterol less than 70 milligrams per deciliter. These findings, therefore, provide support for exploring strategies targeting circulating concentrations of lipoprotein(a) to reduce coronary heart disease events in patients already receiving statins.
The next paper provides important mechanistic results that help us understand pathways in atherosclerotic plague regression. Co first authors, Drs Mueller and Zhu, corresponding author Dr Fazio from Oregon Health and Science University and their colleagues have previously shown that mice lacking an LDL receptor with beta protein 1 in macrophages undergo accelerated atherosclerotic plague formation. However, in the current study they sought to explore the role of macrophage LDL receptor protein 1 during plague regression. They did this by placing EPO E deficient mice on a high fat diet for 12 weeks, then reconstituting their bone marrow using wall type or macrophage LDL receptor protein 1 deficient mice as donors, and finally switching them back to a chow diet for 10 weeks. The authors found that the lack of LDL receptor protein 1 expression in macrophages unexpectedly caused more atherosclerosis regression. Mice with macrophages lacking LDL receptor protein 1 showed less M1 macrophages in the plague and increased CCR7 dependent egress of macrophages from the plague. Thus, loss of macrophage LDL receptor protein 1 has a dual and opposite effect on plague biogenesis, depending on whether the plague is growing or shrinking.
The next paper highlights the intercalated disc, which is a specialized intercellular junction, coupling cardiomyocyte electrical activity in forced transmission as a mechanosensitive signaling hub for causative mutations in cardiomyopathy. First author Dr Trembley, corresponding author Dr Small from University of Rochester School of Medicine and Dentistry and their colleagues showed that myocardin related transcription factors associated with desmosome proteins of their intercalated disc in both murine and human hearts. Genetic deletion of myocardin related transcription factors in cardiomyocytes led to rapid onset of dilated cardiomyopathy in response to pressure overload hypertrophy. Furthermore, myocardin related transcription factors were required for the maintenance of sacromere and intercalated disc integrity under pathological stress. These findings, therefore, provide a unique link between the intercalated disc and mechanosensitive transcriptional regulations. Since myocardin related transcription factors redistribute from intercalated disc in human heart failure, this may represent a novel signaling complex present in cardiomyopathic characterized by desmosome dysfunction.
The next paper investigated the association of blood pressure with peripheral arterial disease events, using data from the ALLHAT Trial. Co first authors Drs Itoga and Tawfik, corresponding author Dr Chang from Stanford University School of Medicine and their colleagues found that both lower systolic blood pressure of less than 120 and higher systolic blood pressure of above 160 millimeters of mercury were both associated with higher rates of peripheral arterial disease events. Diastolic blood pressure less than 70 and a pulse pressure above 65 millimeters mercury were also associated with increased rates of lower extremity peripheral arterial disease events. Given that the recent revised blood pressure guidelines advocate lower systolic blood pressure targets for overall cardiovascular risk reduction, the authors called for future, further refinement of optimal blood pressure targets, specific for peripheral artery disease.
The final original paper this week provides the first integrated atherosclerotic disease risk calculator to incorporate risk factors including high sensitivity C reactive protein, family history, and coronary artery calcium data. First and corresponding author Dr Khera from UT Southwestern Medical Center and colleagues used 3 population-based cohorts to develop Cox Proportional Hazards Models for the outcome of atherosclerotic cardiovascular disease. The derived Astro-CHARM model incorporated factors like age, sex, systolic blood pressure, total and HDL cholesterol, smoking, diabetes, hypertension treatment, family history of myocardial infarction, high sensitivity c reactive protein, and coronary artery calcium scores. The model performance was validated externally in a 4th cohort, and shown to improve risk prediction compared with traditional risk factor equations, and showed good discrimination in calibration in the validation cohort. A mobile application and web based tool was developed to facilitate the clinical application of this tool, and is available at www.astrocharm.org.
And that brings us to the end of this week's summaries. Now for our featured discussion.
Gosh, I am learning for the first time today that it's terribly inconvenient to lose my voice when I am a podcaster. This is Carolyn Lam and our featured discussion that I am so excited about, but the cool thing is the thing we are talking about is so hot that you don't even need me to say anything. And what we are talking about is the ORBITA Trial. That was greeted with as much hype and hoopla and sensationalism since its publication in 2017. I am so proud to have the first and corresponding author Dr Rasha Al-Lamee from National Heart and Lung Institute Hammersmith Hospital in London. I also have Dr Ajay Kirtane from Columbia University Medical Center in New York Presbyterian Hospital and the Cardiovascular Foundation in New York as the editorialist for the paper. And finally, our associate editor Dr Manos Brilakis from UT Southwestern. Rasha, why don't you just take it away and just tell us, what is your paper focusing on in this week's issue?
Dr Rasha Al-Lamee: The paper that was published in this issue in circulation is basically our second analysis of the ORBITA Trial, a substudy analysis. Essentially, looking at the primary endpoint and the secondary endpoints of ORBITA, and having a look at those patients from ORBITA and seeing whether there was any association between their invasive physiological assessment using FFR and ISR at the pre-randomization stage and seeing whether the level of ischemia on ISR or FSR was associated or predicted in the way in which they performed in terms of their endpoints. To see whether there was any difference in the placebo control efficacy of angioplasty in those patients who have more or less severe ischemia on their invasive physiological assessment.
Dr Manos Brilakis: First off, that's a phenomenal paper, and I think she puts things into perspective. I know Ajay put an excellent tutorial. I think all of us were surprised about the findings. You would expect that the more ischemia, that you might see a little more response. Any thoughts as to why there wasn't such an association?
Dr Rasha Al-Lamee: I think it's so difficult because, of course, as we all know from the primary paper that was published in The Lancet, in terms of the primary endpoint, which would be change in exercise time and the difference between the two groups, the difference is actually much smaller than we expected. And when we have such a small difference in exercise time, the ability to be powered enough to be able to split that endpoint based on stratification of invasive physiology becomes very difficult, and we're perhaps underpowered to be able to do that.
Where we did see a very great effect in terms of the primary assessment in The Lancet paper was in stress echo ischemia. What we saw is those patients who had angioplasty were far more likely to have an improvement, or indeed, a normalization of their ischemia on their stress echo. Where we saw a big difference the two groups we were then clearly powered to be able to stratify those patients based on their invasive physiology, and for that secondary endpoint we saw that, in fact, tied to your stenosis or the lower your ISR or FRR, the more likely you are to have an improvement in stress echo, having had placebo controlled angioplasty.
Dr Manos Brilakis: Ajay, I know you had a lot of things insight into the vision of the tutorial for the ORBITA Trial. What are your thoughts about the findings?
Dr Ajay Kirtane: I would, first of all, congratulate Rasha and the ORBITA team, there are others, for not only doing the main trial, but for conducting these detailed analyses, which were clearly set up ahead of time, and that's been one of the critiques of the trial is why were patients with normal-ish range FFRs included. Well, part of it was to test this hypothesis, and perhaps to show that there would be a correlation between the change in the FFR, if you will, and the endpoints that were measured.
So, I think that that's the first part, that this is actually a scientific experiment, and a thoughtful one in doing so. I think exactly as Rasha said though, if there is a limited signal, with respect to the overall trial, then further subsetting is less likely to show a significant signal. I think that's exactly what the investigators found. The only other comment I would make though is, I would commend Rasha and the team for producing other analyses that are novel in this manuscript including the freedom from angina analysis, as well as responding to some of the earlier critiques of the trial and not using specific methodologies to adjust the baseline differences improves. Those are also included in this analysis.
Dr Manos Brilakis: Yeah, absolutely, I think that was very enlightening to see, the freedom of angina. And I know there was some questions whether that might change the overall findings from the studies, so there is some quality of life benefit. Rasha, what is your thoughts about this? I mean, you must understand this study better than anyone else. People who have stable angina, should they undergo PCI or not?
Dr Rasha Al-Lamee: I think the freedom from angina signal was very important, and obviously not something that we had pre-specified, so it wasn't reported in the primary analysis. We're obviously much more able now, since we've published that primary analysis to do secondary analyses and look at things that perhaps we haven't pre specified. And it's interesting to see that 20% more patients are free from angina having had angioplasty vs. placebo. Having said that, to me, it's a fantastic finding, but still a little unexpected. Much less than we might expect looking at unblinded data, or our unblinded clinical experience. I would have expected much higher levels from freedom of angina.
Dr Rasha Al-Lamee: I think what we know, and what we've seen both from this paper, very importantly, and also the primary manuscript, is that the efficacy of angioplasty is very tightly linked to the improvement in ischemia. We've actually, in fact, got more papers that are coming out from our group recently. And that you can predictably tell your patients that if I sense a lesion that's causing a reduction in ISR or FFR, and potentially symptoms, then I will improve your ischemic burden.
What I think is more tricky is how much I will relieve your symptoms, or make you feel better. That may be because symptom assessment itself is very tricky, and perhaps that actually just diagnosing cardiac angina is actually a very difficult thing. The easiest way to piece out improvement in symptoms is to find those patients who become free of angina because, of course, that's the binary end point. When we look at grades of symptoms, and whether their angina frequency improves, or whether the level of angina improves in terms of PCI, then I think it becomes much harder, especially in a blinded trial where, of course, when people come back, even with atypical chest pain, it will still be recorded as potentially angina because, of course, both the investigators and the patients have no idea what they've had done, which is quite different from real life where, of course, you are able to think more about whether this chest pain might indeed be from the heart or from other causes.
Dr Manos Brilakis: Perfect, thank you very much. And I would completely agree with you that, the study was perfect. And, as Ajay said, it is something that we needed, and more of them should be done. And I think you are right that this is the best way to piece out the symptom improvement.
Ajay, any final comments?
Dr Ajay Kirtane: I think that the toughest challenge with trials like this is to really enroll the patients that many of us as interventionists feel would really improve in terms of their symptom class. Even despite these efforts, if one looks at the baseline of anginal frequency in the trial, the means are relatively high, which suggest that the anginal burden, at least in terms of measurements through the anginal questionnaire is not that severe. One could argue that somebody has severe angina that is occurring all the time, that those are types of patients that are hard to randomize in a clinical trial.
I think, at least my overview stepping back perspective of the context of ORBITA within clinical practice, is exactly that. The trial is an important scientific advance, but this does not encompass the answer for every single patient that comes to see us in the office that have a range of symptoms, very severe to less severe. That was something Rasha has been saying all along as well. It's not something that we could over extrapolate this to every patient that we see. So, I think that when the hype dies down, these types of scientific analyses will stand out. They emphasize the need for regular clinical research, and in that way, I think has generated a lot of attention not only to the clinical field here, but also the scientific pursuit of evidence. That's a really magical thing.
Dr Rasha Al-Lamee: I think, if I can add to that Ajay, I think it's probably also sort of the assessment of symptoms is incredibly important. I think many of us, and I'll include myself in this, when we see a very tight stenosis, are happy to essentially correlate any level of symptoms to that tight stenosis. One thing I've learned from all this, I want to see reproducible angina that very much is textbook, cardiac caused chest pain, and the atypical anginas we see, perhaps some of that pain is not from that stenosis, but from somewhere else. Therefore, by fixing that stenosis, we don't necessarily make that pain go away.
Dr Manos Brilakis: Absolutely, and I think you are absolutely, if it is something simple vessel disease, if it's something a little more straightforward, then I think you are right Ajay, that this is much harder, multiple vessel disease especially in people with reduced ejection fraction.
Dr Carolyn Lam: You've been listening to Circulation on the Run! Don't forget to tune in again next week!
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center, and Duke National University of Singapore. Will artificial intelligence replace the human echocardiographer? Aha, well to find out the answer, you have to wait for the incredibly exciting discussion of today's feature paper coming right up after these summaries.
The clinical benefits of the cholesterol ester transfer protein, or CETP inhibitor dalcetrapib depends on adenylate cyclase type 9, or ADCY9 genotype. However, what are the underlying mechanism responsible for the interactions between ADCY9 and CETP activity? In the first paper from today's journal first author Dr Rautureau, corresponding author Dr Tardif from Montreal Heart Institute, and colleagues used a mouse atherosclerosis model inactivated for ADCY9 and demonstrated that loss of ADCY9 protected from atherosclerosis and was associated with improved endothelial function, but only in the absence of CETP. ADCY9 in activation increased weight gain, adipose tissue volume, and feed efficiency, but only in the absence of CETP.
This mouse model reproduced the interactions between ADCY9 and CETP activity observed in patients, and offers new mechanistic insights for the importance of ADCY9 in determining the responses to CETP inhibition. For example, the dal-GenE clinical trial is currently testing prospectively whether patients with coronary disease and the favorable ADCY9 genotype will benefit from dalcetrapib.
The next study addresses the controversy around the cardioprotective effects of Omega-3 polyunsaturated fatty acids, and uncovers signaling pathways associated with eicosapentaenoic acid, or EPA supplementation that may mediate protective effects in atherosclerosis. First author Dr Laguna-Fernandez, corresponding author Dr Bäck from Karolinska Institute, and their colleagues showed that EPA supplementation significantly attenuated atherosclerotic lesion growth. They performed a systematic plasma lipidomic analysis and identified that 18 monohydroxy eicosapentaenoic acid was a central molecule formed during EPA supplementation. 18 monohydroxy eicosapentaenoic acid was a precursor for the plural resolving lipid mediator called resolvent E1.
In the present study, a resolve in E1 was shown to regulate critical atherosclerosis related functions in macrophages through its downstream signaling receptor to transfuse protective effects in atherosclerosis.
Are there racial differences and long-term outcomes among survivors of in-hospital cardiac arrest? In the next paper first and corresponding officer Dr Chen from University of Michigan and her colleagues performed a longitudinal study of patients more than 65 years of age who had an in-hospital cardiac arrest and survived until hospital discharge between 2000 and 2011 from the National Get With The Guidelines Resuscitation Registry whose data could be linked to Medicare claims data. They found that compared with white survivors of in-hospital cardiac arrest, black survivors had a more than 10% lower absolute rate of long-term survival after hospital discharge. This translated to a 28% lower relative likelihood of living to one year, and a 33% lower relative likelihood of living to five years after hospital discharge for black versus white survivors.
Nearly one-third of the racial difference in one-year survival was dependent on measured patient factors. Only a small proportion was explained by racial differences in hospital care, and approximately one-half was the result of differences in care after discharge, or unmeasured confounding. Thus, further investigation is warranted to understand to what degree unmeasured, but modifiable factors, such as post-discharge care may account for the unexplained disparities.
The next study provides insights into a novel mechanism of atherogenesis that involves protease-activated receptor 2, a major receptor of activated factor 10, which is expressed in both vascular cells and leukocytes. Co-first authors Dr Hara and Phuong, corresponding author Dr Fukuda from Tokushima University Graduate School of Biomedical Sciences, and their colleagues showed that in ApoE-Deficient deficient mice, protease-activated receptor 2 signaling activated macrophages and promoted vascular inflammation, increasing atherosclerosis.
Furthermore, they showed that in humans, plasma-activated factor 10 levels positively correlated with the severity of coronary artery disease, suggesting that the signaling pathway may also participate in atherogenesis in humans. Thus, the protease-activated receptor 2 signaling pathway may provide a novel mechanism of atherogenesis and serve as a potential therapeutic target in atherosclerosis.
The next paper tells us that biomarkers may help to predict specific causes of death in patients with atrial fibrillation. First and corresponding author Dr Sharma and colleagues from Duke Clinical Research Institute evaluated the role of biomarkers in prognosticating specific causes of death among patients with atrial fibrillation and cardiovascular risk factors in the ARISTOTLE trial.
They looked at the following biomarkers: high sensitivity troponin T, growth differentiating factor 15, N-terminal pro-B-type natriuretic peptide, and interleukin 6. They found that sudden cardiac death was the most commonly adjudicated cause of cardiovascular death, followed by heart failure and stroke or systemic embolism deaths. Biomarkers were some of the strongest predictors of cause-specific death, and may improve the ability to discriminate among patients' risks for different causes of death.
How do the complement and coagulation systems interact in cardiovascular disease? Well in the final original paper this week, first author Dr Sauter, corresponding author Dr Langer from Eberhard Karls University Tübingen, and their colleagues used several in vitro, ex vivo, and in vivo approaches as well as different genetic mouse models to identify the anaphylatoxin receptor C3AR and its corresponding ligand C3A as platelet activators that acted via intra -platelet signaling, and resulted in activated platelet fibrinogen receptor GP2B3A. This in turn mediated intravascular thrombosis, stroke, and myocardial infarction. This paper, therefore, identifies a novel point of intersection between the innate immunity and thrombosis with relevance for the thrombolic disease of stroke and myocardial infarction.
That wraps up with week's summary. Now for our featured discussion.
Can we teach a machine to read echocardiograms? Well today's feature paper is going to be all about that. I am so excited to have with us the corresponding author of an amazing, and I think, landmark paper, Dr Rahul Deo from the One Brave Idea Science Innovation Center and Brigham and Women's Hospital in Boston, as well as our associate editor Dr Victoria Delgado from Leiden University Medical Center in The Netherlands. Now let me set the scene here. We know that echocardiography is one of the most common investigations that we do in cardiology, and in fact even outside of cardiology, and it is hands down the most accessible, convenient tool to image the heart.
Now let's set this up by remembering that echocardiograms are performed with machines, but led by echocardiologists like me. Now this is really scary Rahul because I think your paper is trying to say ... Are you trying to put people like me out of business?
Dr Rahul Deo: Definitely not. I think what I'm hoping to do is actually two things. One of them is, despite the fact that it's an accessible and safe tool, because it needs people like us, it's probably not used as often as ideally it could be. So part of our hope was to democratize echocardiography by being able to take out some of the expenses from the process so that we can hopefully get more simpler studies done at an earlier stage in the disease process. Because in many ways, at least from my experiences being an attending, it feels like if we could just have gotten to these patients earlier we may have been able to start therapy that could've changed the disease course, but our system can't really afford to do huge numbers of echoes on asymptomatic patients. Really we were trying to find some way of facilitating this by at least helping out on trying to quantify some of the simple things that we do with echocardiography.
Dr Carolyn Lam: I love that phrase, democratizing echo. And you're absolutely right, if we could put it in the hands of non-experts and help them interpret them, we could really lead to detecting disease earlier, and so on and so forth. Wow. But everyone's wondering, how in the world do you go about doing that?
Dr Rahul Deo: One of the things that's really been amazing in these last five years or so is that the field of computer vision, so the field by which computers are trained to mimic humans in terms of visualizing, recognizing, identifying images, has really advanced, and incredibly rapidly. And one of the reasons for that is that the video game type of computing system, the same things that go into Playstations and such, have resulted in much, much more rapid computing. And that's allowed us to train more complex models.
So that's one of the things that's changed, and also, it's just much easier to get our hands-on training data. So machines can be trained to do things, but they need lots of examples. And the harder the task, the more examples they need. So the widespread availability of digital data has made that easier, though I would say that it wasn't that easy to get our hands on enough echocardiography data to be able to train. But in general, almost any task where there's enough data has been solved on the computer vision side. So this has really been an exciting advance in these last few years. So we thought we could very well just used these same technologies on a clinical problem.
Dr Carolyn Lam: Okay, but Rahul what are you talking about here? Like the machine's actually going to recognize different views, or make automated measurements? That's the cool thing, frankly, that you've written about because we know that the machines can already kind of do EF, ejection fraction, but you're talking about something way bigger. So tell us about that.
Dr Rahul Deo: Yeah, so there are many cute examples in the popular press about machines being able to recognize the differences between cats and dogs, or some breeds of dogs. And so if you think about things that way, it really shouldn't be that much more difficult to imagine recognizing between different views, which probably are much more dramatically different than different breeds of dogs. So you could really just take the same models, or the same approaches, give enough examples, label them, and then say figure out what the differences are.
And I think one of the challenges with these systems is they're often black boxes. They can't tell us exactly what it is that they're using, but when it comes to something like recognizing whether something is an apical four chamber view or a parasternal long axis view, we actually don't care that much as to how it is that the computer gets there. We just wanted them to do it accurately, and that's one of the places for some of these computer vision models. It's a field broadly called deep learning, and it's just great at achieving complex tasks.
So, once you recognize views, then the other thing that computers have been shown to be able to do is recognize specific objects within an image. For example, you could give an entire football field and you could find a single player within it. You could recognize where the players are, where the ball is, where the grass is. So computers can distinguish all those things too. And then once you know where something is, you can trace it and you can measure it. So in that sense it's very similar to what a human reader would do, it's just broken down into individual steps, and each one of those needs to be trained.
Dr Carolyn Lam: You put that so simply so that everyone could understand that. That's so cool. You mentioned, though, accuracy. I could imagine that a machine would likely interpret one image the same way again and again, and that addresses something that we really struggle with in echo doesn't it? Because, frankly, one reader against another, we always know. Ejection fraction has got a plus minus seven or something, and then even within the same reader you could read the same thing and say something one day, and say something the other. So this is more than just automating it, is it?
Dr Rahul Deo: Yeah, so it's certainly making it more consistent, and the other thing that we were able to do, I mean once you can teach it to identify and traces the contours of the heart in one image you can have it do it in every single image within the video, and every single video within the study. So now, I mean it's quite painful. I know this from my own experience in terms of tracing these things, so a typical reader can't trace 150, 200, 300, 500 different hearts, that's not going to happen. So instead, they'll sort of sift through manually, pick one or two, and if there's variability from one part of the study to the other, that really won't be captured.
And in this case, the computer will very happily do exactly what you ask it to do, which is to repeat the same thing again and again and again, and then be able to average over that, capture variability. So that's one of the tasks that is much more easy to imagine, setting a computer who won't talk back to you and won't resist and won't refuse to actually taking on the mundane aspect of just getting many, many, many more measurements. And that could happen not only in a single study, but also could happen more frequently. So you could imagine that, again, there's just not that resistance that's coming from having to have an individual do these things.
Dr Carolyn Lam: Oh, my goodness, and not only does he not ... well he, machine, not say no, I mean they don't need to take time off or weekends off. We could get immediate reports directly. Oh my goodness. Victoria I have to bring you in on this. We knew as editors when we found this paper that this is something we just have to publish in Circulation that's going to be groundbreaking. Could you tell us a little bit more about what you think the implications of this is?
Victoria Delgado: I think that this is a very important paper because it's a very large study and it's sets, I would say, three important questions that we deal every day in clinical practice. One is how to reduce burden in very busy echo labs by facilitating the reporting of the echoes and the interpretation of the echoes. Second: to have an accurate measurement and quantification of the images that we are acquiring, and third: this is recognition of the pattern.
And I think that this very important, particularly in primary care because, for example in Europe here, echocardiography is not really in the primary care and the patients are being referred to secondary level hospitals or third level hospitals. That means that the waiting days sometimes is too long. If we train the general practitioners, for example, to do simple echocardiograms with the handheld systems which are also the technologies that are coming and are really available in your iPhone, for example, on your phone, you can get an echocardiographic evaluation of a patient that comes to a general practitioner.
And if you don't have too much knowledge on interpretation, these tools that can have recognition of the pattern of the disease can trace a red flag and say, okay this patient may have this disease or may have this problem, you should consider sending or referring this patient to us at Leiden Hospital where he's going to have a regular check-up and a complete echocardiogram. That could lead to less burden in very busy labs and only refer the patients in a timely manner to the centers when they have to be referred, when the others can wait of can be referred much later.
I think that that's important, and next two technologies that are coming now and it will be very important, some groundbreaking technologies. One is the handheld systems, the ones that you can have in your phone, the ones that you can have in your tablet for example. And the other one is going to be the artificial intelligence to, if not diagnose completely, at least to recognize the pattern that there is a pathology where we need to focus, and we need to act earlier.
Dr Rahul Deo: I think that one place we would like to see this used is in a primary care setting where you have individuals who have risk factors that we know would be risk factors, for example, for let's say heart failure with preserved ejection fraction. But really, my experience in that phase of clinical practice is there's a lot of resistance from patients to get on the medications. So hypertension is, at that point, often, I just got worked up because I had a hard time finding parking, and so on, and so on, where there's just a natural resistance.
So if you could imagine having objective measures describing, let's say how their left atrium is doing at that point, how it looks the next year, what the change in therapy is doing, all these things, you actually can bring in that quantification at a low enough cost that makes it actually practical, then that would be one place we could imagine motivating or intensifying therapies on the basis of something like this.
And I think one area we have to admit we didn't solve is we haven't solved the ability to facilitate getting the data in the first place. We do know that there are these focused workshops around trying to get some simple views, and more and more of our internal medicine residents are able to get some of these, but we can't dismiss that this is still an important challenge in terms of being able to get the images. What we want to do is say, well you can get some images and we can help you interpret them and quantify in an effort to try to motivate therapies being initiated or intensified in a way that's sometimes difficult to do in the current system.
Dr Carolyn Lam: So, Rahul and Victoria, you both mentioned that one of the key aspects is the acquisition of the echo. Not just the machine that does it, but also who takes the images that will then be automatically analyzed. So, Rahul, do you think that sometimes you're going to invent something that will replace even the acquisition, or maybe even simplify it so that we may not need Doppler anymore?
Dr Rahul Deo: One of the things that we thought about was, we wanted to limit ourselves to views that might be easier to acquire, in part because we wanted to reduce the complexity of the study and yet still try to capture as much information as possible. And getting back to the first part of your question, you could imagine that recognizing a view is not that different from recognizing that a view is 10 degrees off from where it should be. You could imagine training a computer to do just that very same thing too. It could recognize a slightly off axis apical four chamber view and guide you into correctly positioning the probe, and you could even imagine a robotic system that does this and just takes the person out of it all together. In part because a very skilled sonographer can quickly look at something and say, oh I just need to tilt my wrist this way and move it this way. I was always humbled by that because I never could quite do that myself.
But in the same way, and in the way, that's happening is that an image is recognized, and then the reference image is held in one's brain, and then they just know from experience what needs to be done to turn one into the other. But that very well-oiled machine could very well be taught to do that exact same thing too.
Dr Carolyn Lam: Oh wow. That is just totally amazing. I know the listeners are being blown away by this just as I am. Let me just end by asking for any last words, Victoria and Rahul, of the clinical application of this. When are we going to have this primetime? What do you think?
Victoria Delgado: I think that this is coming. This is one, for example, of the first studies showing the feasibility of this technology. In terms of accuracy, probably we need improvement, but that depends very much on the quality of the echocardiographic data that we obtain. And in the future, I think that we are going to rely more and more on this technology, and we will have the expert view for those cases that are ambiguous or where the technology has limitations. But in terms of accuracy, for example, I can imagine one of the clinical scenarios that we face in everyday clinical practice is the evaluation of the effect of the treatment in heart failure patients for ejection fraction, and in patients, for example, treated with chemotherapy to see changes in ejection fraction.
That, if we do it manually as we do now, we know that we have limitations in terms of the own viability of the observer. If you leave it for artificial intelligence, maybe that viability may be reduced, and you may be better in terms of adjusting the medication if needed. Because you removed completely what would be the individual viability. So these are the fields that probably I see more and more application of this technology in order to improve the reproducibility of the measurements and accuracy. But yeah, for that we need probably very good image quality, and I see in echocardiography we always tend to say, yeah the image quality is not that good. I'm sure that echocardiography can give you much more than just using through the echocardiography. You can use contrast, you can use many other techniques in order to improve the image quality. And artificial intelligence, the better the image quality is, probably the better it's going to be as well, the accuracy of the measurements and the recognition of disease.
Dr Carolyn Lam: Wow, and Rahul?
Dr Rahul Deo: I completely agree with Victoria. I think that we're going to have to be clever about where we incorporate something like this into the current clinical workflow. You have to choose your problem carefully, you have to understand it. Any system like this is going to make some mistakes. To figure out how to minimize the impact of those mistakes, and at the same time add benefit and potentially enable things that wouldn't even be done. So I think that the fun stuff is yet to come here in terms of really incorporating this in a way that can really change clinical practice.
I want to add one thing that I really haven't mentioned. And we, at this point, really just focused on trying to mimic the stuff that we're already doing. Part of the motivation of this work is to try to potentially see things that we can't even see right now and try to potentially predict onset of disease or early latent forms of something that would really be difficult to detect by the human eye. And we've seen examples of that in some of the other fields around radiology, and I think that's going to be a place that would be augmenting beyond what we're even doing currently.
But of course, the challenge is that the system has to be interpretable enough that we understand what it is that it's seeing, because otherwise I'm sure we'll be reluctant to embrace something clinically that we don't understand.
Dr Carolyn Lam: You've been listening to Circulation on the Run. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. Sacubitril-valsartan reduces the risk of cardiovascular mortality among patients with heart failure with reduced ejection fraction. However, what are its effects on kidney function and cardiac biomarkers in people with moderate-to-severe chronic kidney disease? Well, stay tuned to find out, as we will be discussing the results of the UK Harp III Trial, right after these summaries.
The first original paper this week reveals that inhibition of a long non-coding RNA may serve as a novel molecular therapy for aortic aneurysms. First author, Dr Li, corresponding author, Dr Maegdefessel from Technical University Munich, and colleagues, identified the long non-coding RNA H-19 with functional relevance in experimental aortic aneurysm progression in two mirroring models, a novel genetically mutated mini-pig model, as well as end-stage human disease. They found that H-19 mediated expression levels of the transcription factor hypoxia inducible factor 1-Alpha. Which, in the chronic hypoxic environment of an aneurysm, triggers apoptosis in aortic smooth muscle cells. This study, therefore, introduces inhibition of H-19 as a novel molecular therapy to limit smooth muscle cell death in progressing aortic aneurysms.
The next study provides insights into molecular mechanisms underlying heart failure progression in chronic pressure overload. Co-first author, Dr Chiang and Alsina, co-corresponding authors, Dr Heck, from Utrecht University, and Dr Wehrens, from Baylor College of Medicine, and their colleagues developed a novel and unbiased way to comprehensively study protein phosphatase 1 or PP1 interactors in a mouse model of progressive heart failure induced by elevated afterload. This so-called PP1 interaction enabled simultaneous interrogation of multiple pathways relevant to heart failure pathogenesis. They found nine specific PP1 interactors that were strongly associated with heart failure progression. Among these, the PP1 regulatory subunit 7 was shown to play a central role by regulating the PP1 interaction, and by acting as a competitive molecular sponge of PP1.
In clinical trials of direct oral anticoagulants for atrial fibrillation, patients with end stage kidney disease on dialysis were excluded. Today's study answers the question, "What are the outcomes with Apixaban in dialysis dependent end stage kidney disease patients with atrial fibrillation?"
Co-corresponding authors Dr Siontis and Dr Saran from University of Michigan and their colleagues performed a retrospective cohort study of Medicare beneficiaries included in the United States Renal Data System from 2010-2015. All eligible patients were those with end stage kidney disease and atrial fibrillation undergoing dialysis who had initiated treatment with an oral anticoagulant.
In prognostic score-matched analysis, Apixaban was associated with lower rates of major bleeding compared with Warfarin, whereas there was no difference in stroke or systemic embolism. Patients on standard dose of Apixaban of 5 mg had a lower rate of stroke and death compared to those on reduced dose Apixaban of 2.5mg. Thus, Apixaban may be associated with superior safety and comparable effectiveness outcomes as Warfarin in dialysis patients with atrial fibrillation. However, these findings require confirmation in a randomized trial setting.
Does Canagliflozin have benefits in people with chronic kidney disease, including those with an Estimated Glomerular Filtration Rate, or EGFR, between 30 and 45, in whom the drug is currently not approved? First author Dr Neuen, corresponding author Dr Perkovic from the George Institute of Global Health, and their colleagues performed a secondary analysis of the CANVAS Program to describe outcomes in participants with and without chronic kidney disease, as well as according to baseline kidney function as measure by EGFR.
They found that the effect of Canagliflozin on HbA1c was progressively attenuated at lower EGFR levels, but blood pressure and body weight reductions were comparable. The reduction in risk of major adverse cardiovascular events, hospitalization for heart failure and progression of kidney disease appeared similar across different levels of kidney function, down to an EGFR of 30. Safety outcomes were also mostly consistent, but the risk of hypoglycemia may increase as EGFR declines.
That wraps it up for our summaries, now for our feature discussion.
Cubitalis-valsartan improves outcomes in patients with heart failure with reduced ejection fraction, and we know that from the Paradigm trial, but what about its effects on kidney function and cardiac biomarkers in people with chronic kidney disease?
Well, this week's feature paper provides important randomized trial data addressing this question. To discuss it, we have none other than the first and corresponding author, Dr Richard Haynes from University of Oxford, as well as our editorialist for the paper, Braden Manns and Matthew James, both from University of Calgary and in addition, we have Dr Justin Ezekowitz, associate editor who manages paper, and Justin is from University of Alberta.
Welcome gentlemen, we have a full house. Richard, could you start by sharing about your trial and your findings?
Dr Richard Haynes: So, the trial was called UK Harp-III, and it was really a pilot trial, just to work to investigate the effects of Cubitalis-valsartan on patients with chronic kidney disease, and in particular to see what it did for their kidney function in the short term, and also what it did to other measures of interest like their blood pressure and cardiac biomarkers.
It was a randomized control trial double blind, among just over 400 people with chronic kidney disease, and we compared Cubitalis-valsartan with Irbesartan, which is standard of care for most of these patients. Our primary outcome was really to look at the effects of these drugs on kidney function when it was being precisely measured in hospitals. We found, actually, that Cubitalis-valsartan had very similar effects to Irbesartan on kidney function. So, there was no real difference in kidney function at any point in the trial between patients who were allocated the Cubitalis-valsartan or those allocated Irbesartan.
Dr Carolyn Lam: Richard, the way you described it I'm sure you're prepared for this question so why Irbesartan as the control versus Valsartan?
Dr Richard Haynes: That's a very good question and a question asked quite often. There were six of one and half a dozen of the other. We could have chosen Valsartan. The difficulty with that is that Valsartan doesn't have a license indication for the treatment of chronic kidney disease so if we found a difference people might have said we just chosen an inferior comparator, so we chose Irbesartan because that does have an indication for the treatment of proteinuria kidney disease and obviously that leaves us open for the question about how different Valsartan and Irbesartan are. My opinion is they might be subtly different, but I don't think the difference is big enough to really impact these results in any meaningful way.
Dr Carolyn Lam: Indeed, and I know Braden and Matthew you have thought about it a lot. Congratulations on the beautiful editorial. I love the way you set the context in the heart failure world where perhaps we have noted something different with regards to kidney function. Would either of you like to start the ball rolling with discussing that?
Matthew James: Sure, this is Matthew James. So really the Paradigm Heart Failure Trial is a very important place to start in thinking about the effect of these medications on kidney function. That was a very large trial that did report changes in estimated Glomerular Filtration Rate and did show a small but statistically significant change in kidney function between the Sacubitril-valsartan arm and the control arm. There are many potential mechanisms for that, but it is important to realize that there were limitations in the population specifically around chronic kidney disease due to the level of kidney function that the patients were enrolled in to the study. So, some of the patients with more advanced chronic kidney disease wouldn't have been included in the Paradigm Heart Failure Trial so this trial is actually giving us more information about patients with kidney disease who we would expect to be at higher risk of seeing progressive loss of kidney function or progression of their kidney disease.
Dr Carolyn Lam: Thanks for setting that up and just to clarify for the audience here so in Paradigm EGFR went down to 30 right, and here in UK Harp we are talking about measured GFR down to 20. Am I right?
Dr Richard Haynes: Eligibility was actually determined by the EGFR, the estimated GFR.
Yeah it went down to 20, up to 60. We also had a much more proteinuria in the patients in Paradigm.
Dr Carolyn Lam: Right, and do you have a take Richard on why the results seem different from at least the secondary analysis that Milton Packer wrote about on its effects on kidney function in Paradigm?
Dr Richard Haynes: I do have a take. I'm really interested to hear what Braden and Matthew thought. My take was that probably when you've got heart failure one of the major determinants of how well your kidneys work is actually how well your heart is working. That is probably one of the major determinants in that setting and because we know Sacubitril-valsartan has such beneficial effects on cardiac function in people with heart failure perhaps it's not surprising that it then is protected by kidney function a little bit better than people given Enalapril in Paradigm. However, in UK Harp III, we had a group of patients whose kidney had very definite kidney disease and probably the determinants of kidney progression quite different and having any impact on their heart function probably wouldn't really be noticed because the effect of their kidney disease would outweigh that. Perhaps, Sacubitril-valsartan doesn't have any beneficial effects on the kidney itself. As far as we can tell, from what is a relatively small and a relatively short trial.
Dr Carolyn Lam: Justin, I mean you come from the heart failure world too just like me. What was your take?
Dr Justin Ezekowitz: I think there are a number of features here we should take a step back and think about. Number one is as Richard outlined there is a lot more proteinuria here than would typically be seen in a heart failure related population. So, the comparator between the two groups, while similar in overlap while co-manage these patients is somewhat different in terms of what the result we are looking for. So, you know, it brings to mind that what we look at in the secondary analysis in for example Paradigm, is simple EGFR creatinine changes versus here we are looking at a much more sophisticated measure of GFR plus also looking at a comparator that is known to reduce proteinuria and I would say stabilize or not change or prevent their progression of renal disease in the larger trials in the renal population. So, it's a slightly different population, a slightly different comparator as well. The importance in the choice of comparators becomes really important when we are looking for this specific effect.
Now, to Richard's point, which he opened with, which is talking about this as a pilot project to a larger outcome trial, it is hard to know whether or not the effects that Richard and his team on the NT-proBNP, troponin, and other effects would play out in the larger cardiovascular outcomes trial that would be potentially different results than simply a GFR change or proteinuria change. I would be interested in Richard's thoughts on that and Matt and Braden's as well.
Matthew James: Maybe we can also get add another question to Richard which this was a really well-done study and you talked about it being relatively small and certainly by heart standards this was a relatively small pilot study with a limited duration of follow up. By kidney standards, this is a fairly this would be a usual sized clinical trial and so getting all these patients in the trial was a wonderful result to start with and while the study wasn't directly looking at safety of these medications, there is some I think assurance we have some tolerability data at least with this medication and the challenge as Richard would well know in managing patients with chronic kidney disease once they developed more advanced chronic kidney disease GFR is less than 30 is often difficult to use medications because of side effects, high potassium, and things. The most challenging types of patients we see are patients with lower levels of kidney function and with low ejection fractions. So at least this paper provides some hope that we've got a medication that is reasonably well tolerated in that population.
I think that when Richard talks about this being a pilot study where a lot of patients, in fact patients with chronic kidney disease are much more likely to die from heart disease than they are to develop end stage renal disease. For many types of patients that is true at least. So, we are often thinking about what medications could be used to improve cardiovascular outcomes. So, in that sense, again given that the majority of the structural heart disease is not necessarily reduced heart function but is left ventricular hypertrophy I'm sure, and perhaps Richard has some comments as to the next study that might be considered given this medication seemed tolerable. It didn't have the effects that were perhaps hoped on progression although in the Paradigm sub study there was only a difference of 0.5 ml per minute and they were powered to detect 3 ml per minute in this study but actually the immediate hemodynamic drop was about 3 ml per minute and then kidney function was relatively stable thereafter. So hard to imagine this study would have showed a difference in kidney function now in retrospect but potentially this opens up some additional studies to look at cardiovascular outcomes in patients with chronic kidney disease who don't have reduced ejection fraction.
Dr Richard Haynes: I think that's a really good point. I think it would be fascinating to see the results of the Paradigm Trial with Sacubitril-valsartan in patients with heart failure and preserved ejection fraction. Nevertheless, I think this trial does raise the hypothesis that this might be a drug that could improve regardless of whether it has any effect on the kidney or not. It could be possibly be used for improving cardiac outcomes but I just don't think the trial that we've done is enough to justify that at the moment. I think it's a good indicator that it may well work, but I think before anybody could recommend that with much enthusiasm I think it would require a large outcomes trial but focusing quite rightly on cardiovascular outcomes in people with chronic kidney disease which as Matthew said is actually the major burden of disease in those patients.
Dr Justin Ezekowitz I think the question remains though is if as a pilot trial at that time as a longer-term trial would there be any difference because the mechanism of action of Sacubitril is different from that of Irbesartan and that was also shown in the nice table you have in the supplemental file which talks about the Sacubrital lapse concentration going up with the lower GFR's. So, there is the potential for those small subgroups where the GFR is lower they may have a substantial benefit over a longer period of time, not measured necessarily by GFR but measured by clinical outcomes. I think that is where the balance of getting the pilot trial versus a longer follow-up clinical outcomes trial is really important to get.
I may actually just state one other thing or two. First, it's really important to investigate or initiate a trial and this is one of critical parts of why we do clinical trials. Medicine tests the effects initially a pilot and then hopefully a larger trial.
The second is the importance of randomization here. We all think that the shiny new medications are important but getting randomization in trials like this done are really advanced knowledge, so we know what to do with the medication if we are faced with it or if we want to make an important choice for a patient that we can really make a point for the patient that we will base it on the best scientific knowledge.
The third point that I would just come back to something else that we have not talked about yet is this overall is a neutral trial. There are no major effects that were seen but the importance of getting a neutral trial done and published is really critical as this advances the field potentially, so others can now decide what to do and perhaps launch larger trials with cardiovascular outcomes or decide to do a different comparator or different other tasks forward. So, this one we emphasize it is critically important to get these types of trials done and then published.
Dr Carolyn Lam: You know Justin, I couldn't have said it better and completely echo your words. We are so proud to be publishing your paper Richard and that beautiful editorial in circulation. So, I'm just going to wrap up then because in the absence of better data at the moment what is the main take home message of this trial for patients with CKD right now and their care providers. I would love to start with Braden because you wrote about it in the editorial as well. What do you think of the take home messages?
Braden Manns: Well again I think that we often struggle when peoples GFRs are in the 20 to 30 range with identifying a medication that's tolerable particularly in the context of people with reduced ejection fraction. I must say personally I would now be comfortable using this medication in patients with reduced ejection fraction who remain symptomatic who have GFRs in the 20 to 30 range. Those patients aren't that common but feel comfortable now using that type of medication there despite the fact that most patients weren't necessarily enrolled in the Paradigm study. A much larger population though of patients with structural heart disease but not reduced ejection fraction who have chronic kidney disease. It is not clear to me where this medication fits in the armamentarium. As Justin says it certainly wouldn't use this in preference to an ace inhibitor or an angiotensin receptor blocker at this point. So, it's hard to know where it fits without some larger studies looking at cardiac outcomes.
Matthew James: I agree with Braden. I think we are already seeing this medication now enter practice here in Canada. There is this overlap in population between the patients with kidney disease and impaired left ventricular ejection fraction, so this is actually very helpful for us when we see these patients in practice around the appropriateness of continuing these medications in this patient population.
Dr Justin Ezekowitz: So, I think it's critically important to remember the take home message here is to do proper clinical trials and then do again the large trial because without that would not really advance in knowledge. There could be a huge value to a newer medication or potentially the old ones are still just as good as we if we continue them safely.
Dr Richard Haynes: I'd like to echo what everybody said already really. I mean I think what Justin just said trial is the key. We can't get away from the need for randomized control trials. I'm pleased that we've managed to deliver this one. In terms of a clinical take home message I think if I was a patient with kidney disease and heart failure, especially with reduced ejection fraction, I hope that I would feel a bit more comfortable to take this drug now knowing is it going to benefit me from a cardiovascular point of view it doesn't seem it is going to do my kidneys any harm either. So, hopefully it will reassure more patients that they can yield the benefits of a trial this drug has.
Dr Carolyn Lam: Great stuff! Thank you so much gentlemen. This has been such an enlightening conversation.
Thank you very much to audience for joining us today. You've been listening to Circulation on the Run. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
FDG-PET CT was recently introduced as a new tool for the diagnosis of prosthetic valve endocarditis. However, can we improve on its diagnostic performance? Well, to learn more you have to listen to the upcoming featured discussion, right after these summaries.
Our first original paper this week describes a potential novel therapy for hypertension. In this study from first author Dr Hu, corresponding author Dr Soong, from Yong Loo Lin School of Medicine National University of Singapore, authors showed that galectin-1 is a key regulator for proteasomal degradation of CaV 1.2 channels. L-type CaV 1.2 channels are known to play crucial roles in the regulation of blood pressure. In a series of elegant in vitro and in vivo experiments, the authors showed that galectin-1 promotes CaV 1.2 degradation by replacing CaV-beta and thereby, exposing specific glycines for polyubiquitination. This mechanistic understanding provided the basis for targeting CaV 1.2 galectin-1 interaction and demonstrated the modulatory role that galectin plays in regulating blood pressure. The study, therefore, offers a potential novel approach for the therapeutic management of hypertension.
Direct oral anticoagulants or DOACs, are surpassing warfarin as the anticoagulant of choice for stroke prevention in non-valvular atrial fibrillation. However, DOACs outcomes in elective peri-procedural settings have not been well elucidated and remain a source of concern for clinicians.
The next paper in today's issue was a meta-analysis designed to evaluate the peri-procedural safety and ethicacy of DOACs versus warfarin. For author Dr Nazha, corresponding author Dr Spyropoulos, from the Feinstein Institute for Medical Research in Northwell Health at Lenox Hill Hospital in New York, reviewed the literature for data from phase three randomized controlled trials comparing DOACs with warfarin in the peri-procedural period among patients with non-valvular atrial fibrillation. Sub study from four trials were included namely RE-LY, ROCKET-AF, ARISTOTLE, and ENGAGE-AF. The short-term safety and ethicacy of DOACs and warfarin were not different in patients with non-valvular atrial fibrillation peri-procedurally. Under an uninterrupted anticoagulation strategy, DOACs were associated with a 38% lower risk of major bleeds compared to warfarin.
The next paper presents results from the Sarcomeric Human Cardiomyopathy Registry or SHARE, which combined longitudinal data sets curated by eight international hypertrophic cardiomyopathy specialty centers to provide a better understanding of the factors that contribute to heterogeneous outcomes in lifetime disease burden in patients with hypertrophic cardiomyopathy. First and corresponding author Dr Ho from Brigham and Women's Hospital and colleagues analyzed longitudinal clinical information on 4,591 patients with hypertrophic cardiomyopathy. By examining the data set spanning more than 24,000 patient-years, the mortality of patients with hypertrophic cardiomyopathy was shown to be 3-fold higher than the general population at similar ages. The lifetime cumulative morbidity of hypertrophic cardiomyopathy was considerable, particularly for patients diagnosed before age 40 years and patients with sarcomere mutations. Atrial fibrillation and heart failure were the dominant components of disease burden. Thus, young age of diagnosis and the presence of sarcomere mutations are powerful predictors of adverse outcomes in hypertrophic cardiomyopathy. These findings highlight the need for close surveillance throughout life and the need to develop disease-modifying therapies.
The final original paper this week provides molecular insights into atherosclerosis and it shows that defective base excision repair of oxidative DNA damage in vascular smooth muscle cells promotes atherosclerosis. Now, we know that atherosclerotic blocks demonstrate extensive accumulation of oxidative DNA damage, predominantly as 8-oxoguanine lesions. In today's paper, first author Dr Shah, corresponding author Dr Bennett from University of Cambridge and colleagues studied levels of 8-oxoguanine and its regulatory enzymes in human atherosclerosis. They found that human plaque vascular smooth muscle cells showed defective nuclear 8-oxoguanine repair, associated with reduced acetylation of the base excision repair enzyme 8-oxoguanine-DNA-glycosylase-1. Furthermore, correcting the base excision repair defect in vascular smooth muscle cells alone markedly reduced plaque formation, thus indicating that endogenous levels of oxidative DNA damage in vascular smooth muscle cells promoted plaque development.
And that brings us to the end of this week's summaries. Now for our feature discussion.
Prosthetic valve endocarditis is a life-threatening complication. However, making a timely diagnosis of prosthetic valve endocarditis before the occurrence of severe complications is really difficult. Now, FDG-PET CT has recently been introduced as a new tool for the diagnosis of prosthetic valve endocarditis. However, previous studies reported only modest diagnostic accuracy and may have been hampered by confounders. But today's study, our feature study in Circulation, addresses this issue. We have none other than the corresponding author, Dr Ricardo Budde from Erasmus Medical Center in Rotterdam, the Netherlands, and our dear associate editor, Dr Victoria Delgado, who is in Leiden University Medical Center, also in the Netherlands.
So please tell us, how does your study help us address this issue of the accuracy of FDG-PET CT
Dr Ricardo Budde: What we actually did is that of course endocarditis is a relatively rare disease, so we had six hospitals in the Netherlands that collaborated on this study and in each of the hospitals we searched for PET CT scans that were performed in patients with a prosthetic heart valve, either because they were suspected of having endocarditis, or if they were meant for other purposes, for example oncological follow-up. Then we grouped all those CT scans together, interpreted the PET CTs anew by dedicated interpreters, and then compared the findings with the actual diagnosis in the patient, which of course is always difficult in endocarditis because to make the diagnosis is difficult. So, also, one year follow-up period was included in that to be absolutely certain whether the patient had endocarditis or not. By taking this whole cohort of patients, we were able to determine the diagnostic accuracy of PET CT, as well as by using a logistics model, identify confounders which influence the diagnostic accuracy of PET CT.
I think the study that we did addresses several important aspects and the way it helps physicians in actually interpreting and implementing PET CT to diagnose endocarditis is two-fold. First of all, we identified confounders that have to be taken into account when interpreting and using the PET CT. For instance, low inflammatory activity at the time of imaging and the use of surgical adhesive during a prosthetic heart valve implantation are confounders which should be taken into account when interpreting the PET CT. Furthermore, the guidelines have always insisted on not to use or use it very cautiously PET CT within the first three months after prosthetic heart valve implantation. However, we showed that actually this period after implantation does not necessarily have to be taken into account as also a good diagnostic accuracy can be obtained within the first three months after implantation.
Dr Carolyn Lam: Ricardo, that's wonderfully put. I don't do a CT, PET CT, routinely. In fact, I am echocardiologist and it used to be that infective endocarditis was diagnosed with echo. So Victoria, tell us, how does echo stand now with this information?
Dr Victoria Delgado: That's a very good question but I think the guidelines set a very clear figure of how the diagnostic workup of patients with prosthetic valve endocarditis should be performed. An echocardiography is the first imaging technique. The point is that transthoracic echocardiography in patients with suspicion of prosthetic valve endocarditis is very challenging. In terms of ideal, echocardiography is probably the best imaging technique to do first to evaluate whether it is endocarditis or not. It's difficult, we have to take into account that for a specific prosthetic valve, particularly mechanical, the shadowing can make that we don't see the [inaudible 00:10:22] and sometimes it's difficult, particularly in the early phase immediately after implantation, all the inflammation can be confounder for presence of endocarditis. In those cases, I think that this study provides additional and important data highlighting which are the confounders when you use PET CT to evaluate depressions of endocarditis. I think that, when you take into account those confounders, the accuracy of this technique is very good in order to make or help in the diagnosis of these patients. So, echocardiography, I think that will remain as our first imaging technique to rule out [inaudible 00:11:10] we can see but in those cases where the diagnosis is not confirm or rule out with transthoracic and transesophageal echocardiography this study provides additional data and important data showing that PET CT is a valuable complementary imaging diagnostic test for these patients.
Dr Carolyn Lam: Ricardo, would you agree with that because I think your study also emphasized that perhaps FDG-PET CT should be implemented early in the diagnostic workup to prevent the negative confounding effect of the low inflammatory activity? So how do we put this all together?
Dr Ricardo Budde: Well actually, I agree with Dr Delgado that echocardiography is and should be the first-line test that you do if you have a patient that has a suspicion of endocarditis. I mean, the advantages of echocardiography are many and it's non-invasive, it's bedside-available if needed, it's patient-friendly, and it provides a huge amount of information so you should always start with echocardiography. However, sometimes it can be difficult by echocardiography, for the reasons just explained by Dr Delgado, and I think then PET CT should be considered. And when you want to do a PET CT, then you should do it early within the diagnostic workup.
Actually, in the article, one of the figures is a flow chart which we provide, and it provides information on how we think PET CT can best be implemented in the workup of endocarditis. In this flow chart we also start with doing an echocardiography and also, importantly, consult the endocarditis time to make initial classification of whether it's a rejected, possible, or definite prosthetic heart valve endocarditis. After that, you can follow the flow chart and see when you can best implement PET CT, in our opinion.
Dr Carolyn Lam: Indeed Ricardo, I am so glad you brought up this figure and listeners, you have to take a look at it. I can imagine that everybody will be using this and discussing it and how to incorporate this in the workflow. And indeed you do start with either transthoracic or transesophageal echo and blood cultures, so thank you for clarifying that.
Now, for our clinicians out there, are there any situations you may be telling us to be a little more careful? Could you put it simply for us when it comes to the FDG-PET?
Dr Ricardo Budde: You mean when not to perform a PET CT?
Dr Carolyn Lam: Yeah, or when we have to be really careful about inaccuracies.
Dr Ricardo Budde: I think, of course, the confounders that we indicate in the article, especially if bioglue has been used by the surgeon during the initial surgery. We know that bioglue can be seen on a PET CT as a false positive uptake of FDG and it's also important to note that this is a phenomenon that can persist for a very long time after a valve implantation. It could be for years, so especially that I think is a very important confounder to take into account and be careful when you interpret PET CT or use the PET CT and always read the original surgical report if it is available to obtain this information.
Dr Carolyn Lam: That's wonderful advice. Victoria, do you have anything to add?
Dr Victoria Delgado: No, I think that Dr Budde explained perfectly this figure that is key in the article and also how to evaluate patients with suspected endocarditis of prosthetic valve. One thing that sometimes we forget is starting from the first step that is a good clinical history which includes also a good evaluation of previous history and, if possible, what has been done in the patient. I think that this key information to understand the findings on the echocardiography, transthoracic or transesophageal, and the subsequent investigations that you are going to perform. Either CT which is considered, for example, when you have a definitive prosthetic valve endocarditis and you want to rule out potential complications such as abscess, for example, and if you perform a PET CT or other imaging modalities that then also indicate the presence of infection like, for example, [inaudible 00:15:26] leukocytes with PET, for example.
Dr Carolyn Lam: And I just want to end up with one little point. Ricardo, how about the fact that part of your results don't corroborate the ESC guideline recommendations that they say you have to avoid FDG-PET in the recently implanted prosthetic valve. How do you feel it's going to play out for clinicians?
Dr Ricardo Budde: Well, I think the 2015 ESC guidelines on endocarditis are a very important document. One must take into account that the inclusion of PET CT in the ESC guidelines was a major step, and some might say that it was a little premature to include the use of PET CT because the number of data that was out there were still relatively limited. I think it's something that we are learning along the way. Now that we are using PET CT more often we are more aware of what we do to findings that we get and also the findings that we have within specific timeframes after the implantation of a prosthetic heart valve. One of the things that I think is desperately needed also at the moment is to have a prospective study where we would do PET CT in patients after implantation of a prosthetic heart valve that do not show any signs of endocarditis where we do PET CT just to determine these normal uptake values. I think that would be a major contribution to the whole learning experience that we're currently having with implementing PET CT within prosthetic heart valve endocarditis.
Dr Carolyn Lam: Indeed, and Ricardo your paper has added significantly to our understanding. Readers, remember, it's Figure 6 of our feature paper this week. It is a beautiful figure. Pick it up, take a look. In the meantime just thank you so much Ricardo and Victoria for joining me today.
Listeners, don't forget to tune in again next week.
Ticagrelor has shown superior efficacy to clopidogrel in the management of acute coronary syndromes. But what about in patients undergoing PCI for stable coronary artery disease? Well, our feature paper this week gives us answers to this question but you're going to have to wait to the feature discussion to hear these answers. That's coming up right after these summaries.
Our first original paper this week shows that RBM20 mutation carriers have an increased risk of arrhythmias. You may recognize RBM20 as that splicing factor which targets multiple pivotal cardiac genes such as Titin and Calcium/Calmodulin-Dependent Kinase 2 Delta or CAMK2D. In today's paper first author Dr van den Hoogenhof and co-corresponding authors Dr Pinto and Creemers from Academic Medical Center Amsterdam, compared the clinical characteristics of RBM20 and Titin mutation carriers and used RBM20 knock out mice to investigate the downstream effects of RBM20 dependent splicing. They showed that loss of RBM20 disturbed calcium handling and led to more pro-arrhythmic calcium releases from the sarcoplasmic reticulum. Patients that carried a pathogenic RBM20 mutation had more ventricular arrhythmias despite a similarly depressed left ventricular function compared to patients with a Titin mutation.
Targets of RBM20 splicing were enriched for calcium and ion handling genes, most notably CAMK2D and type 2 Ryanodine receptor. Loss of RMB20 induced an increased L-Type Calcium current density, intracellular calcium overload, increased sarcoplasmic reticulum calcium content and increased spontaneous calcium releases which all could be attenuated with treatment with an L-type calcium channel blocker. Furthermore, these results suggest that RBM20 mutation carriers should be closely monitored for potential electrical disturbances and cardiac arrhythmias even in the early stages of disease.
Echocardiographic quantitation of degenerated mitral regurgitation is recommended in clinical guidelines but is it really scalable to routine clinical practice? First author Antoine, corresponding author Sorano from Mayo Clinic Rochester Minnesota and their colleagues looked at more than 3900 patients diagnosed with isolated mitral valve prolapse between 2003 and 2011 and to any degree of mitral regurgitation quantified by any physician or sonographer in routine clinical practice. They found that in multi-variable analysis routinely measured effective regurgitant orifice area was associated with mortality independent of left ventricular ejection fraction and systolic diameter symptoms or age and comorbidities. Furthermore, compared with general population mortality excess mortality appeared for moderate mitral regurgitation with an effective regurgitant orifice area above 20 squared millimeters and became notable with an effective regurgitant orifice area above 30 squared millimeters which then steadily increased with even higher levels of above 40. Thus, quantitation of degenerative mitral regurgitation is scalable to routine clinical practice with strong independent prognostic power when performed routinely by multiple practitioners.
The next study identifies a novel mechanism of lipid homeostasis that is linked to a pseudo gene associated with the recently discovered apolipoprotein known as APOO. Co-first authors Montasser and O'Hare, corresponding author Dr Mitchell from University of Maryland School of Medicine in Baltimore, performed an array based association analysis in more than 1100 Amish subjects and identified a variant strongly associated with LDL cholesterol levels. They identified a founder haplotype on chromosome 5 which was associated with a 15 mg/dl increase in LDL cholesterol after recombination mapping, the associated region contained eight candidate genes. Using a zebra fish model to evaluate the relevance of these genes to cholesterol metabolism they found that the expression of the transcribed pseudo gene APOOP1 increased LDL cholesterol and vascular plaque formation. Thus, based on these data the authors proposed that APOOP1 regulates levels of LDL cholesterol in humans and represents a novel mechanism of lipid homeostasis.
The Orion-1 trial demonstrated that inclisiran which is a small interfering RNA therapeutic that targets PCSK9 MRNA with [inaudible 00:05:42] produces significant LDL reduction. In today's study from Dr Ray from Imperial College London and colleagues, the authors described in detail the effect of inclisiran on prespecified secondary lipid and lipoprotein outcomes over time for up to 210 days and also described the individual variation and response in these measures. They found that a single 300 milligram dose of inclisiran lowered non-HDL cholesterol at day 180 by 35% and a second dose at day 90 resulted in a 46% reduction at day 180. Similarly a single dose of 300 milligrams of inclisiran reduced apolipoprotein B by 31% at day 180 and a second dose of 300 milligrams administered in day 90 reduced apolipoprotein B by 41%. Significant reductions in all atherogenic lipoproteins measured were sustained through today 210. Furthermore, every individual had a reduction of apolipoprotein B and non-HDL cholesterol at 180 days with the 300 milligram two-dose regimen of inclisiran. Thus, inhibiting the synthesis of PCSK9 through small interfering RNA may be a viable alternative to monoclonal antibodies with respect to effects on atherogenic lipoproteins and that brings us to the end of our summaries. Now for our feature discussion.
Ticagrelor has superior efficacy to clopidogrel in the management of acute coronary syndrome but it has not really been assessed in patients undergoing PCI for stable coronary artery disease. For our feature paper today it's going to shed some light and help us with this question and these are the results of the STEEL-PC trial. I'm so pleased to have with me right now the corresponding author Dr Robert Storey from University of Sheffield in the UK as well as our associate editor who managed this none other than Dr Stefan James from Uppsala University. Thank you.
Rob, could you tell us what is the issue you tried to address and because your study is not that simple, we're not used to thinking about these pharmacodynamic and kinetic studies so could you explain a bit of what you did?
Rob Storey: Well it's quite a few concepts that we assessed in this study. We've got data from a number of studies showing that Ticagrelor both at doses of 90 mg twice daily and 60 mg twice daily is more reliable and superior P2Y12 inhibitor compared to clopidogrel. We've got this issue of very variable response to clopidogrel with some poor responders and some high responders and a range in between. That's fairly well established and part of this study was to get more data on the 60 mg dose of Ticagrelor in these stable CAD patients undergoing PCI and get some pilot data on clinical efficacy obviously this study was not part of clinical outcomes.
But, there's another issue in terms of adenosine uptake so Ticagrelor has a relatively weak effect on adenosine uptake into red cells and other cells and this may or may not explain some of its clinical effects including some adverse effects such as dyspnea. We wanted to get a better idea of the impact of Ticagrelor at both these doses on adenosine uptake.
Dr Carolyn Lam: Could I ask ... Okay this may be naïve. I'm not an interventional cardiologist but why would you expect something different in an acute coronary syndrome compared to stable coronary artery disease? Is there an underlying hypothesis there?
Rob Storey: Well there can be changes to their differences in platelet reactivity although those aren't particularly great and overwhelmed really by P2Y12 inhibitor like Ticagrelor which gives such reliable inhibition of the P2Y12 receptor. But, there have been a limited number of groups that have looked at adenosine uptake and so we wanted to get independent confirmation or not of whether Ticagrelor therapeutic concentrations impacting on adenosine uptake and get some ideas of whether it's affecting circulating adenosine levels. That's an important question in terms of understanding the mechanisms and actions of Ticagrelor.
Dr Carolyn Lam: Got it. Thanks for breaking it down so nicely. So what did you find?
Rob Storey: What we found was surprisingly that we saw no impact of Ticagrelor at either dose and at any time point within a month after PCI on adenosine uptake. That is the circulating levels of adenosine and the rate at which adenosine is taken up by cells in the blood mainly red blood cells. The explanation for that really is that the therapeutic levels of Ticagrelor that you see are not sufficient to impact on adenosine uptake because it's a very weak inhibitor of the adenosine uptake pathway known as the MT1. The therapeutic levels are just not getting up to a high enough concentration to have a significant impact on that.
Dr Carolyn Lam: Stefan, you've thought a lot about this. What did you think of the findings?
Stefan James: I think it's very interesting. Of course, the pharmacodynamic effects that you can measure by pretty simple means, the level of platelet inhibition, it should be similar in ACS and stable coronary artery disease and I think it's sort of confirming what Rob has been showing in other populations with ACS ... we have been very interested in trying to understand the additional mechanisms of action of Ticagrelor... try to understand the mortality rate without the benefit for Plato, for example. Was it only -- platelet inhibition or were there other mechanisms? And, there is a specific Ticagrelor related side effect, dyspnea, which we would have been interested in understanding... is this a mechanism of action? We can't really explain that. There are other mechanisms and other effects that we have seen can also be explained by adenosine, so I thought it was very interesting and important to understand more about these mechanisms.
Dr Carolyn Lam: Yeah.
Stefan James: But I would like to ask you, Rob. Do you think this adenosine hypothesis now, is dead, or should we still try to explore this?
Rob Storey: Well of course in this study what we didn't look at was the adenosine kinetics in the tissue level which is where we hypothesize the dyspnea may arise from stimulation of C5 is in the lung tissue so we're missing that piece of information. It's still conceivable that very weak levels of ENT-1 inhibition may impact from adenosine levels in the tissue. We're not seeing a strong ENT-1 inhibition sufficient to raise circulating levels or something that we can pick up on this in vitro assay.
I think it still remains an open question. We've got this sort of contradictory information from drugs like cangrelor and other drugs in development like Elinogrel where we don't see an impact on adenosine but they still may cause dyspnea. So I think it's a very open question still.
Stefan James: Do you think that your paper gives us additional strength to the hypothesis that the mortality benefit for ticagrelor as seen in Plato is explained by the platelet inhibition and the balance between the reduction in ...
Rob Storey: Well I think what we see really in all these studies is that Ticagrelor is a fantastically effective PTY12 inhibitor. It gives you the best level of platelet inhibition during maintenance therapy out of all the available PTY12 inhibitors. And clearly having such more reliable PTY12 inhibition than clopidogrel could still be driving a mortality benefit in high risk patients so we can't exclude the adenosine pathway contributing to some of the clinical effects but I think this sways me a little bit more to the position of thinking this is most of the benefits through platelet inhibition.
Dr Carolyn Lam: Interesting. So you're on the cutting edge of this. What's the next step then?
Rob Storey: Clearly we can see that very effective and reliable P2Y12 inhibition is important and leads to clinical benefits and I think we need to implement that wherever we're using P2Y12 inhibitors. We need to take that message and use a more consistent therapy rather among those with associated with variable response which doesn't seem to make sense. I think this stable PCI population, their risk has fallen. And we see that in this study, quite a number of patients report a response to clopidogrel but no stent thrombosis.
That really reflects, I think improvements in stent design and implantation techniques, so the implication is that maybe aspirin alone is enough to prevent stent thrombosis with modern techniques if you get a good result but in the higher risk patients particularly the ACS patients it's likely you need much more reliable platelet inhibition and that's why Ticagrelor really provides this security.
Dr Carolyn Lam: So, Rob there is one thing you tested two doses and they seemed to be equivalent at least in antiplatelet inhibition, right? So what does this mean? Should we maybe preferentially use the lower dose from now on, is there still room for the higher dose? Could you share some insights there?
Rob Storey: Well I think one has to be cautious in not jumping to adopt a dose just on the basis of pharmacodynamic data but clearly what we show is that the 60 mg dose of Ticagrelor offers a very reliable and consistent level of PTY12 inhibition and that's likely to be very effective in preventing stent thrombosis in combination with aspirin. We also show signals that were also shown in the Pegasus study that the 60 mg dose may be better tolerated such as with lower levels of dyspnea.
So, there is the option for off label use of the lower dose of Ticagrelor in those who cannot tolerate the high dose due to dyspnea because certainly they'll have better platelet inhibition down titrating from 90 to 60 and if they were to switch to Clopidogrel. So I think our study offers some comfort in terms of that aspect. The only caveat is that you have to be careful not to use strong CYP3A inducers such as some epilepsy drugs with Ticagrelor cause that can increase the metabolism and we did have one case of high platelet reactivity with strong CYP3A inducers so using a higher dose initially I think is a good idea. The label says 90 mg for 1 year following ACS and the 6 is licensed beyond one year as a down titration predominantly.
Our study certainly gives some comfort that down titrating earlier if a patient can't tolerate the 90 for whatever reason, seems to be a justifiable thing. And the other thing is the European guidelines support the use of Ticagrelor off label in elective PCI and our study certainly gives some comfort that off label use and the low risk elective PCI patients of the 60 mg dose can be justified at least from a pharmacodynamic point of view.
Dr Carolyn Lam: Well, thank you because that's exactly what our audience is loving to hear. How do these findings translate into the clinical practice - Would you have any other take home messages for the clinicians listening in?
Rob Storey: Well I think one thing we looked at also was troponin release which is very common after PCI. We didn't see an impact of PTY12 inhibition high levels on troponin release and I think that sort of caveat in terms of that's not going to be the best measure in terms of surrogate for efficacy in the PCI population. The other question really is, how much of the platelet inhibition and how much of the adenosine effects of Ticagrelor influence the clinical outcomes and clearly the studies sways towards the platelet inhibition very consistent high level of platelet inhibition explaining most of the benefits.
Carolyn Lam: You've been listening to circulation on the run, don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. This week's journal features two papers that deal with genetic testing in young athletes and for sudden arrhythmic death, and with findings that may surprise you. They really show the complexities of this era of genetic testing and cardiovascular medicine, and in fact are discussed as growing pains in cardiovascular genetics. You must listen to our feature discussion, which is coming right up after these summaries.
The first original paper this week suggests that targeting fibronectin polymerization may be a new therapeutic strategy for treating cardiac fibrosis. Fibronectin polymerization is necessary for collagen matrix deposition and is a key contributor to increased abundance of cardiac myofibroblast following cardiac injury. In today's paper, first author Dr Valiente-Alandi, corresponding author Dr Blaxall from University of Cincinnati College of Medicine and Heart Institute, and their colleagues hypothesized that interfering with fibronectin polymerization, or its genetic ablation and fibroblasts, would attenuate myocardial fibrosis and improve cardiac function following ischemia reperfusion injury. Using mouse and human cardiac myofibroblasts, authors found that the fibronectin polymerization inhibitor pUR4 attenuated the pathological phenotype exhibited by mouse and human myofibroblasts by decreasing fibronectin polymerization and collagen deposition into the extracellular matrix as well as by myofibroblast proliferation and migration.
Inhibiting fibronectin matrix deposition by pUR4 treatment or by deleting fibronectin gene expression in cardiac fibroblasts confirmed cardioprotection against ischemia reperfusion-induced injury by attenuating at first left ventricular remodeling and cardiac fibrosis, thus preserving cardiac function. In summary, interfering with fibronectin polymerization may be a new therapeutic strategy for treating cardiac fibrosis and heart failure.
The Insulin Resistance Intervention after Stroke, or IRIS trial, demonstrated that pioglitazone reduced the risk of both cardiovascular events and diabetes in insulin-resistant patients. However, concern remains that pioglitazone may increase the risk of heart failure in susceptible individuals. To address this, Dr Young from Yale Cardiovascular Research Center and the IRIS investigators performed a secondary analysis of the IRIS trial. They found that older age, atrial fibrillation, hypertension, obesity, edema, high CRP, and smoking were risk factors for heart failure.
Pioglitazone did not increase the risk of incident heart failure, and the effect of pioglitazone did not differ across levels of baseline risk. It should however be noted that in the IRIS trial, the study drug dose could be reduced for symptoms of edema or excessive weight gain, which occurred more often in the pioglitazone arm. Overall, pioglitazone reduced the composite outcome of stroke, MI, or hospitalized heart failure in the IRIS trial.
The next study highlights the importance of genetic variation in cardiac fibrosis and suggests that while fibroblast activation is a response that parallels the extent of scar formation, proliferation may not necessarily correlate with levels of fibrosis. In this paper from co-first authors Dr Park and Ranjbarvaziri, corresponding author Dr Ardehali, from David Geffen School of Medicine, University of California, Los Angeles, the authors utilized a novel multiple-strain approach known as the Hybrid Mouse Diversity Panel to characterize the contributions of cardiac fibroblasts to the formation of isoproterenol-induced cardiac fibrosis in three strains of mice.
They found that isolated cardiac fibroblasts treated with isoproterenol exhibited strain-specific increases in the levels of activation, but showed comparable levels of proliferation. Similar results were found in vivo with fibroblast activation but not proliferation correlating with the differential levels of cardiac fibrosis after isoproterenol treatment. RNA sequencing revealed that cardiac fibroblasts from each strain exhibited unique gene expression changes in response to isoproterenol.
The authors further identified LTBP2 as a commonly upregulated gene after isoproterenol treatment. Expression of LTBP2 was elevated and specifically localized in the fibrotic regions of the myocardium after injury in mice and in human heart failure, suggesting that it may be a potential therapeutic target. That brings us to the end of our summaries. Now for our feature discussion.
We all know that t-wave inversion is common in patients with cardiomyopathy, however up to a quarter of athletes of African descent, and five percent of white athletes also have t-wave inversion on ECG, but with unclear clinical significance despite comprehensive clinical evaluation. Now, what is the role in diagnostic use of genetic testing beyond clinical evaluation when we investigate these athletes with t-wave inversion? Well we're about to get some answers in today's feature paper, and I'm so pleased to have the corresponding author of the paper, Dr Sanjay Sharma from St. George's University of London, as well as our associate editor Dr Mark Link from UT Southwestern.
Sanjay, please let us know what you did and what you found.
Dr Sanjay Sharma: Well as you rightly say, that up to 25% of black athletes have t-wave inversion, as do three to five percent of white athletes. And these t-wave inversions often overlap with the sort of patterns that you see in patients with hypertrophic cardiomyopathy and arrhythmogenic cardiomyopathy. For example, 80% of people with hypertrophic cardiomyopathy have t-wave inversion as do 60% of patients with ARVC. Now we know that some ECG patterns, t-wave inversions in V1 to V4 are benign in black patients, but the significance of other ECG patterns is unknown. Cascade screening in family members with cardiomyopathy have shown that t-wave inversion may be the only manifestation of gene inheritance, and there are reports to suggest that some athletes with t-wave inversion do go on to develop overt cardiomyopathy. Now when we investigate the vast majority of our patients with t-wave inversion, these are our athlete patients, we don't actually find anything. But over the past decade, also, these has been major advance in next generation sequencing that allows us to perform genetic testing in a large number of genes that can cause diseases, capable of causing sudden death.
And so, we thought we'd investigate the role of this gene testing in athletes with t-wave inversion. We looked at a hundred, 50 black athletes and 50 white athletes who had t-wave inversion, and we investigated them comprehensively with clinical tests. But we also added in a gene panel looking at 311 genes implicated in six cardiac diseases, notably hypertrophic cardiac myopathy, arrhythmogenic cardiomyopathy, dilated cardiomyopathy, left ventricular non-compaction, long QT syndrome, and the brugada syndrome. We found that 21% of our athletes were then diagnosed with a cardiac disorder capable of causing sudden death, and the vast majority of these people had hypertrophic cardiomyopathy. And this diagnosis was based on clinical evaluation. When we looked at gene testing, we found that gene testing only picked up a problem in 10%. So, the diagnostic yield of gene testing was half that of comprehensive clinical investigation.
When we actually looked at athletes who had nothing wrong with them in clinical investigation, and actually had a gene mutation, we found that only 2.5% of athletes who had t-wave inversion but clinically normal tests, actually had something wrong with them. And our conclusions were that gene testing picks up only half the athletes that clinical testing does, and gene testing is only responsible for identifying 2.5% of athletes with t-wave inversion, where clinical tests are negative. That was the summary of our study in short. We did find that black athletes were less likely to have a positive diagnosis of cardiac myopathy than white athletes, and black athletes are also less likely to have a genetic mutation capable of causing a cardiomyopathy than white athletes.
Dr Carolyn Lam: First and foremost, congratulations on such a beautiful paper, and so wonderfully summarized as well. It really seems to fly in the face, doesn't it? Of the way we've been discussing personalized medicine and saying that we're going to start whole genome sequencing everyone and that's going to provide all the answers for future disease risks. I mean, if I'm not wrong, what your paper is trying to tell us is that at this moment we don't have good examples where genetic testing may trump clinical diagnoses, and in fact we should be still focusing on a comprehensive clinical evaluation of patients and in the absence of a genotype we should learn to question what we're doing in genetic testing. Do you agree with that?
Dr Sanjay Sharma: You couldn't have said that more precisely. As I've said, the diagnostic yield of clinical testing was 21% versus only 10% with genetic testing. The diagnostic yield of pure genetic testing in people with otherwise completely normal findings clinically was only 2.5%. And the other thing that I forgot to tell you was that genetic testing, if we included genetic testing in addition to comprehensive assessment, cost us three times as much as clinical investigation on its own, and had we relied solely on genetics, and nothing else, it would have cost us ten times more than clinical testing. So our cost per making a diagnosis using genetics only would have amounted to $30,000 per condition.
Dr Carolyn Lam: Wow, what a great wake up call. Mark, you've thought a lot about this and in fact there was another paper in this week’s journal that has very complimentary messages. In fact you invited an editorial by Dan Roden, and I really loved his title of it, "Growing Pains in Cardiovascular Genetics." Would you maybe add your thoughts in relation to the other paper, as well as overall?
Dr Mark Link: Sure. Circulation was very interested in these papers. These are really ... Now, as Dan Roden says, "Growing pains." Twenty years ago when genetics came out it was looked upon as it was going to completely change our clinical medicine and precision medicine is really relying a lot on genetics. And while ultimately that may be the case, we are in a stage now where the honeymoon is over. And the other paper that was in this same issue was a paper by Hosseini and colleagues, and it was the Clin Gen paper looking at the Brugada Syndrome abnormalities. Now the Clin Gen is an NIH sponsored group that takes individuals from a number of different institutions and actually gene testing, and tries to provide an independent assessment of the abnormality of genes. Previously is was companies that did this. A company would gene test ... They would look for gene abnormalities, try to link it with clinical disease, and they could basically then do just on their patients. But Clin Gen now is trying to tie all those companies together to get a broad consortion and to look at genetic abnormalities and whether they're truly pathologic, where there's areas of unknown significance, or whether they're truly not pathologic.
So as an example, they took Brugada Syndrome, and they took the different gene abnormalities that have been described from basically different companies and different labs and different institutions, and they looked at the evidence behind the fact that they were truly pathologic, 'cause all 21 genes were defined as pathologic. They found in their independent assessment that only one ended up to be truly pathologic, and the others ones were disputed. And sort of another wakeup call that just because a single company calls a gene pathologic or Brugada Syndrome, does not make it pathologic necessarily. So we all thought these were two very important papers that looked at some of the limitations of genetic testing. We asked Dan Roden, who is really a very accomplished scholar in this field, to provide perspective on this. And I agree, I loved his title, "Growing Pains in Cardiovascular Genetics." And what he did is reviewed the history of genetic testing, and he actually starts before genetic testing and starts with Mendelian genetics, and [inaudible] genetics. And then 23 years ago they started linking that Mendelian genetics to gene abnormalities, especially in diseases such as long QT syndrome and hypertrophic cardiomyopathy.
We've come a tremendous way in diagnosing gene abnormalities and associating them with these underlying cardiac myopathies and hind channel abnormalities. So no one doubts we've come a tremendous way, but there's a long way to go in terms of getting better diagnostic accuracy and really defining where these genetic testing are ultimately going to play out in clinical medicine. So everyone's excited about it, but I think these two papers are two cautionary tales that we do have to remember that genetic testing in 2018 is not the end all and be all.
Dr Carolyn Lam: I love that, cautionary tales. So important. But where do we go from here? What's the take home message for clinicians listening to this today in 2018? I mean is it that perhaps when we do these things we now need to include medical geneticists and genetic counselors as vital partners as we look at this all? Perhaps we need to not forget the primacy of clinical evaluation. What do you think, Sanjay?
Dr Sanjay Shar: Well, there are guidelines from the American Medical Genetics side as to what one defines as a disease-causing mutation. But I agree that we need to be using certified laboratories that can actually interpret the genetic mutations. For example, in our study of athletes, 63% actually had variance of undetermined significance. So they had spinning mistakes in their genes which probably didn't account to anything at all, but had these mutations, or these so called variance of undetermined mutations been interpreted by someone who didn't really know much about this, these could have resulted in false positive results which could cause absolute chaos for an athletes career. So I do think this type of testing has to be governed very, very carefully and needs to be performed in very specialized and certified laboratories.
Dr Carolyn Lam: Indeed. Not just to the athlete, but to their families too, isn't it? Mark, what do you think is the take home message [inaudible 00:16:18]?
Dr Mark Link: I think one of the big take home messages that I took away from these papers is that clinical medicine is not dead. In fact, clinical medicine in this day and age is still the prime way of taking care of patients. Genetic testing is still in its infancy. It doesn't help clinically in too many situations yet. It will in the future. It helps in the diagnosis, it's not as useful in the treatment. So we have a long ways to go with genetics. I like your comment that going forward we're going to need more genetic counselors to make sense of these results. Clinicians are going to have a hard time making sense of these results. I do think that there is plenty of role once a disease causing mutation has been defined, and in that situation it's invaluable in cascade screening in identifying other family members who may be affected, but outside that I do believe and I agree completely with both of you, that clinical medicine is not dead. And clinical evaluation should be number one and should enjoy it's prime time because that's where we still are at. And genetics is still in its infancy and so is cardiology.
Dr Carolyn Lam: Perhaps in selective settings ... We're not talking here about, for example, hypercholesteremia variance, we're not talking about cancer gene variance for which screening may be a little bit more advanced, and we may understand the gene phenotype associations that are perhaps-
Dr Mark Link: I think that understanding gene phenotype associations are going to be critically important in the future. I think, as Sanjay said, the real use of genetic screening now is cascade screening for the family, and there it's invaluable. That you can tell if you've got a co-band with the disease, and with a defined pathological mutation. You can test siblings, sons and daughters, parents to see if any of them have the gene. I think that's where it should be used for sure in 2018.
Dr Carolyn Lam: Thank you so much Mark and Sanjay. So some precautions, some hope. Very, very balanced discussion. So much more we could discuss, so I really want to highly encourage our audience. Pick up this issue. You have to read these amazing papers and the editorials.
Dr Carolyn Lam: So, here's a podcast with all your colleagues, and don't forget to tune in next week.
Dr Carolyn Lam: We start today's podcast with a few words from our Editor-in-Chief, Dr Joe Hill.
Dr Joe Hill: I speak with you today with a heavy heart as we recently lost an esteemed and beloved colleague, Professor Bongani Mayosi. Bongani was a pioneering leader, a renowned investigator, Dean of the Medical School at the University of Cape Town, and an important member of our Circulation editorial leadership team.
Bongani had an abiding passion for the under-served, especially those in his native Africa. He died tragically and suddenly at the early age of 51, just 10 days after recording the podcast you're about to hear.
We mourn the loss of this colleague and our hearts go out to his family. It is a very poignant moment, as we hear his voice once again. We grieve deeply, and are reminded of Bongani's towering achievements and contributions to the betterment of our world.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
CD4-positive T cells play an important role in atherosclerosis, but their antigen specificity is poorly understood. Today's paper describes the first study to detect apolipoprotein B peptide 18 specific CD4 T cells in mice and humans. First author Dr Kimura, corresponding author Dr Ley from La Jolla Institute of Allergy and Immunology and their colleagues constructed novel P18 tetramers to detect human and mouse APOB-specific T cells and assayed their phenotypes by flow cytometry. They found that these P18 specific T cells were mainly anti-inflammatory regulatory T cells in healthy donors, but co-expressed other CD4 lineage transcription factors in patients with sub-clinical cardiovascular disease.
Immunization with P18 reduced atherosclerotic burden in APOE deficient mice and induced antigen specific T regulatory cells. This study therefore, identifies APOB peptide 18 as the first T regulatory APOtope in human atherosclerosis.
The next study suggests that testing intracellular calcium handling in circulating B lymphocytes may be a novel biomarker for monitoring patients with heart failure. During [inaudible 00:02:47] intracellular calcium is released from sarcoplasmic reticulum into the cytoplasm through Type II ryanodine receptor calcium release channels. In heart failure chronically elevated, circulating catecholamine levels cause pathologic remodeling of these Type II receptors, resulting in diastolic sarcoplasmic reticulum calcium leak, thus decreasing myocardial contract [inaudible 00:03:09]. Similarly, skeletal muscle contraction requires sarcoplasmic reticulum calcium release and this occurs through Type I ryanodine receptors. Chronically elevated catecholamine levels in heart failure cause Type I mediated sarcoplasmic reticulum calcium leak, thus contributing to skeletal myopathy and weakness.
In today's paper, first author Dr Kushner. Co-corresponding authors Dr Kitsis from Albert Einstein College of Medicine and Dr Marx from Columbia University, New York hypothesized, that since circulating B lymphocytes express Type I ryanodine receptors, they may be a potential surrogate for defects in intracellular calcium handling due to leaky ryanodine channels in heart failure. Indeed, they found that circulating B lymphocytes from humans and mice with heart failure exhibited remodeled Type I ryanodine receptors and decreased endoplasmic reticulum calcium stores, consistent with chronic intracellular calcium leak. This calcium leak correlated with circulating catecholamine levels. The intracellular calcium leak was significantly reduced in mice treated with S107, which is a drug that specifically reduces ryanodine receptor calcium leak.
Furthermore, heart failure patients treated with LVADs exhibited a heterogenous response. Thus, Type I ryanodine receptor mediated calcium leak in B lymphocytes assessed using flow cytometry may provide a surrogate measure of intracellular calcium handling and systemic sympathetic burden and therefore represent a novel biomarker strategy for monitoring the responses in heart failure therapy.
Hypouricemia and gout are known to be associated with increased risk of cardiovascular disease. And xanthine oxidize inhibitors such as allopurinol and febuxostat are the mainstay of urate lowering treatment of gout, but do they have different effects on cardiovascular risk? First author, Dr Jong, corresponding author, Dr Min from Brigham and Women's Hospital Harvard Medical School in Boston, Massachusetts, studied a cohort of almost 100,000 older Medicare patients with gout and found that there was, overall, no difference in the risk of MI, stroke, new onset heart failure, coronary revascularization are all cause mortality between patients initiating febuxostat compared to those initiating allopurinol. However, there did seem to be a trend toward an increased opiate not statistically significant risk for all-cause mortality in patients who use febuxostat for over three years compared to allopurinol use for over three years. The risk of heart failure exasperation was slightly lower in febuxostat initiators.
The final original paper this week provides important contemporary data on the clinical characteristics in hospital management and long-term outcomes of patients with acute myocarditis. Co-corresponding authors, Dr Ammirati and Kamichi, both from Milan, Italy and their colleagues screened 684 patients with suspected acute myocarditis and recent onset of symptoms within 30 days between May 2001 and February 2017 and included 443 patients with acute myocarditis diagnosed either by endomyocardial biopsy or by increased troponin and edema and late gadolinium enhancement on cardiac magnetic resonance imaging. They showed that among these 443 patients, 118 patients or 26.6% had either left ventricular ejection fraction less than 50% sustained ventricular arrhythmias or a low cardiac output syndrome. While, the 73.4% had no such complications.
Cardiac mortality and heart transplantation at five years was 4.1%, but went up to 14.7% in the patients with complicated presentation and contrast down to zero percent in the uncomplicated cases. Similarly, major acute myocarditis related cardiac events after the acute phase, such as post discharge death and transplantation, sustained ventricular arrhythmias, symptomatic heart failure needing device implantation all occurred in 2.8% at five years, but was much higher in patients with a complicated presentations at 10.8% versus zero percent in the uncomplicated presentations. Thus, the authors concluded that patients with acute myocarditis can be effectively stratified based on their initial clinical presentation. Patients with left ventricular ejection fraction less than 50% at the first echo. Those with sustained ventricular arrhythmias or those with low cardiac output syndrome are at higher risk of cardiac events compared to those without these manifestations.
And that brings us to the end of our summaries. Now, for our feature discussion.
With advances in therapy most deaths in people with HIV are now due to noncommunicable diseases, especially cardiovascular disease. What does the global burden of HIV associated cardiovascular disease really look like? Well we're going to get some answers in today's feature paper. I have with us today the first and corresponding author of the paper, Dr Anubshaw from University of Edinburgh, as well as our associate editor, Dr Bongani Mayosi from University of Cape Town in South Africa.
Dr Carolyn Lam: Welcome to you both. And Anub, what an important question to examine. Could you tell us how you looked into this question and what you found?
Dr Anubshaw: Sure. So, this is a very interesting question from our end and we had in short idea looking at the risk of cardiovascular disease in patients with HIV. And there are many studies of it, varying results. I'm looking at the risk of heart disease and stroke in patients with HIV. So, what we did was a big systematic review to extract all the data out there looking at the risk of heart disease in patients with HIV, we then developed a model that looked at what the overall risk was and then tried to calculate the actual burden of cardiovascular disease attributable to patients with HIV. In some of the work we found, well, primarily we found that the majority of the burden, as expected in Sub-Saharan Africa and that is primarily the cause, in prevalence of HIV is the highest in Sub-Saharan Africa, accounting for about two thirds of all people living with HIV.
Dr Anubshaw: The risk of cardiovascular disease with patients with HIV is twofold higher compared to patients not infected by virus. And there was not [inaudible 00:10:12] variations in the actual burden. The majority of the burden in Sub-Saharan Africa and Southeast Asia.
Dr Carolyn Lam: Wow, Sub-Saharan Africa and Asia Pacific, isn't it? Oh my goodness, Bongani, your views please on these standing results from Africa.
Dr Bongani Mayosi: Yes. I think these results are actually very important in the Sub-Saharan African region, reaching the, at the center of the HIV/AIDs epidemic in the world. And particularly important now that we are finding people and are on treatment and that they are growing older and there's a thriving proportion of people above the age of 60, they are on HIV infection and therefore the whole question of cardiovascular disease in these patients has become very important and clearly now these data suggest that HIV [inaudible 00:11:08] for cardiovascular disease, but what is more important [inaudible 00:11:14] they are important [inaudible 00:11:17] for cardiovascular disease, but also a [inaudible 00:11:22]. [inaudible 00:11:23] such as another vascular condition, which is pulmonary hypertension associated with HIV detection. [inaudible 00:11:35] with the increase of the number of people on treatment, these particular conditions are becoming [inaudible 00:11:43] in the context of how to [inaudible 00:11:48], but is an important condition in the African continent. So that the overall burden of cardiovascular disease is likely to be greater than is estimated here because the study is only estimating atherosclerotic cardiovascular disease.
Dr Anubshaw: That brings up a very intriguing question, Anub. Could you at all distinguish between atherosclerotic risk factors and the role that played versus more HIV specific risk factors, such as the medication, the degree of HIV control, level of inflammation, for example? Now, of course in a meta-analysis this may be difficult, but just your thought.
You're absolutely right from a meta-analysis point of view it's very difficult for a couple of reasons. Firstly, we do not have individual patient level data, so we couldn't really see a [inaudible 00:12:45] level which patients are on [inaudible 00:12:47] therapy and what their personalized risk factors are. Varying schools of thought estimated around the candidates that they need, which kind of portrays a risk of heart disease in the [inaudible 00:12:59] artery in patients with HIV. And what we think may be happening there, one that HIV represents a degree of sub-clinical inflammation that leads to vascular inflammation, which then leads to accelerated atherosclerosis and there's some fantastic mechanistic evidence looking at this where, workers have looked at vascular inflammation in the arteries in patient HIV can go through control and you do get much more vascular inflammation. There is some evidence about the fact that the [inaudible 00:13:31] therapy itself can cause [inaudible 00:13:34] and therefore increase the risk of atherosclerotic heart disease.
And finally, some risky behavior is probably much more, have a look at HIV for example, smoking entered the [inaudible 00:13:46] etc., etc. and there may be a degree of overlap in terms of or correlation in terms of risk factors being much more common in HIV patients, which are more conditional for atherosclerotic heart disease. I think a combination of all those three things probably explain the increase risk of atherosclerotic heart disease and strokes in these patients.
Dr Carolyn Lam: Indeed. Your paper is so important to raise awareness of that very risk. I mean, if I could please re-iterate, you show very clearly that people with HIV are the two fold increase risks of cardiovascular disease and that that global burden had tripled over the last two decades. I think that your paper really shines a bright light in this area, that we have to study further because the clinical implications are enormous aren't they? Because we're using guidelines developed in non-HIV patients to perhaps treat these cardiovascular diseases in HIV patients and there may be other pathophysiologic mechanisms like you just mentioned. What do you think are the main clinical implications of your paper?
Dr Anubshaw: The clinical implication is quite important because what the burden estimate show is that the majority of burden is in no or little information and therefore the resource of those innovations are quite limited, but there's one condition that has been treated so well in these countries. One of the main success stories of medicine, over the last two or three decades and how they've tackled HIV, who runs PEP for has made intrical virals available so widely in the Sub-Saharan African regions, while there's other highly prevalent regions. And they set up logistically clinics to deliver and scare for persons with HIV and if you and I will see that the survival in these patients [inaudible 00:15:39] just mentioned. Then, these patients are at more high risk of other among AIDs related conditions, such as strokes and heart disease. What you now have in these poor resource countries or limited resource countries, where clinics and the logistical support is only set up to deliver cardiovascular risk prevention strategies and therapy. Which is not expensive in terms of antihypertensives, in terms of [inaudible 00:16:06] and in terms of lifestyle factors.
So, I think there is [inaudible 00:16:10] here that the region has to further reduce the cardiovascular burden in this population.
Dr Carolyn Lam: Bongani, you too recognize the very important clinical implications and in fact invited the editorial by Priscilla Sue and David Waters from San Francisco General Hospital. I love the title of it. Is it time to recognize HIV as a major cardiovascular risk factor? Bongani, what are your thoughts?
Dr Bongani Mayosi: I think it is time we should be considering the HIV as a risk factor for cardiovascular disease. You know these data arriving from this [inaudible 00:16:48] are quite compelling and when you look, for example at that this is a hot study [inaudible 00:16:55] in the editorial and conferred by HIV, it is almost the same as the other [inaudible 00:17:02]. I mean if you go into it now that in fact the European Society of Cardiology it is already [inaudible 00:17:12] in HIV infected individuals with [inaudible 00:17:19]. So, if now may be entering their [inaudible 00:17:27] of practice, they consider HIV as a significant risk factor for cardiovascular disease and maybe contribute to bring a drug that will modify outcome. I do think though that because of the mechanism of cardiovascular disease it [inaudible 00:17:45] HIV it is not common on the basis of atherosclerotic disease. In Africa as an example, we know very well that the patient tend to [inaudible 00:17:55] with not a lot of traditional risk factors of cardiovascular disease, in fact, atherosclerotic diseases such as [inaudible 00:18:07] still have a relatively low level of [inaudible 00:18:10].
So, we still, I think need to discover what are the other [inaudible 00:18:14] mechanisms that are involved, I mean they do that very much more targeted drug [inaudible 00:18:21] where it needs to be tested, that don't know our traditional interventions for reducing risk and preventing cardiovascular disease. So, there is need for further research here and the mechanisms and specific intervention. That is the important in this large HIV infected populations because at the moment there at least 27 million people in the world, living with HIV who already facing a major public health issue on a global scale.
Dr Carolyn Lam: Exactly and all these new research efforts, paying attention to this, making sure that we don't underestimate cardiovascular risk and HIV based on traditional risk calculators. All of this starts with awareness and with important papers such as yours, Anub. Thank you so much for publishing that with us at Circulation.
Well, listeners you know how important this is globally, so please share this podcast with your colleagues and don't forget to tune in next week.
Current guidelines recommend measurement of one of the cardiac specific isoforms of cardiac troponin complex. However, what's the utility of combining measurements of troponins I and T in the early diagnosis of acute myocardial infarction? Well, you have to wait for our upcoming feature discussion, but it's coming right up after these summaries.
The first original paper this week sheds light on the genetic basis and mechanisms of bicuspid aortic valve, the most common congenital heart defect in the population. We know that bicuspid aortic valve is an autosomal dominant trait with variable expression and incomplete penetrants suggestive of genetic and environmental modifiers. In the current study, first author Dr Gharibeh, corresponding author Dr Nemer from University of Ottawa, and authors of the Bicuspid Aortic Valve Consortium assessed cardiac structure and function in mice, lacking a GATA6 allele. They found that GATA6 heterozygous mice had a highly penetrant type of bicuspid aortic valve with right and left leaflet fusion, which is the most frequent type found in humans. GATA6 transcript levels were lower in human bicuspid aortic valve as compared to normal tricuspid valves. Mechanistically, GATA6 haploinsufficiency disrupted valve remodeling and extracellular matrix composition through dysregulation of the importance in the molecules including matrix metalloproteinase nine. Cell-specific inactivation of GATA6 reveal that an essential rule for GATA6 in secondary heart field myocytes. Thus, the study identifies a new cellular and molecular mechanism underlying bicuspid aortic valve.
In the field of cardiac regeneration, c-Kit positive adult progenitor cells were initially reported to produce new cardiomyocytes in the heart. However, more recent genetic evidence suggests that such events are exceedingly rare. Today's paper provides insights into this discrepancy and it is from first author Dr Maliken, corresponding author, Dr Molkentin from Howard Hughes Medical Institute Cincinnati Children's Hospital Medical Center. The authors took a novel approach of deleting the necessary cardiogenic transcription factors, GATA4 and GATA6, from c-Kit expressing cardiac progenitor cells to determine whether true de novo cardiomyocyte formation would occur. They found that deletion of the necessary cardiogenic transcription factors, GATA4 and GATA6, from these c-Kit+ cardiac progenitor cells remarkably resulted in greater apparent cardiomyocyte derivation from the c-Kit+ cells. Deletion of GATA4 from c-Kit–derived endothelial progenitors altered the integrity of the endothelial cell network in the heart, resulting in greater c-Kit+–derived leukocytes entering the heart and fusing with cardiomyocytes.
Thus, they demonstrated a new role for GATA4 in endothelial differentiation, specifically showing for the first time that GATA4 is essential for vascular development by the c-Kit lineage. The study shows that leukocyte to cardiomyocyte fusion is the primary basis for path lineage tracing results, incorrectly suggesting that c-Kit+ cardiac progenitor cells generated de novo cardiomyocytes in the heart.
Lecithin–cholesterol acyltransferase, or LCAT, is the sole enzyme that esterifies cholesterol in the plasma. Its role in the supposed protection from atherogenesis remains unclear, because mutations in LCAT can cause more or less carotid atherosclerosis. Addressing this conundrum, co-first authors Drs. Oldoni and Baldassarre, co-corresponding authors Dr Kuivenhoven from University Medical Center Groningen, Dr Holleboom from Academic Medical Center Amsterdam, and Dr Calabresi from University of Milano in Italy hypothesized that genetic mutations causing complete LCAT deficiency versus partial LCAT deficiency would be differentially associated with carotid atherosclerosis in carriers of LCAT mutations. To study this, they looked at 74 heterozygotes for LCAT mutations who are recruited from Italy and the Netherlands and who were assigned to complete versus partial LCAT deficiency. These were also compared to 280 controls. Using carotid intima-media thickness as a measure of atherosclerosis, the authors demonstrated that carriers of LCAT mutations leading to complete LCAT deficiency exhibited less carotid atherosclerosis, indicating a reduced risk of cardiovascular disease.
By contrast, however, carriers of LCAT mutations leading to partial LCAT deficiency showed marginally more atherosclerosis. The association of mutations in LCAT with subclinical atherosclerosis appeared to be related to the capacity of LCAT to esterify cholesterol on apoB-containing lipoproteins since the abnormal LCAT present in the partial deficiency was only active on this class of lipoproteins. These important findings bear relevance for pharmaceutical strategists that target LCAT.
After a bioprosthesis aortic valve replacement, what is the incidence, correlates, and outcomes of hemodynamic valve deterioration? First author Dr Salaun, corresponding author Dr Pibarot from Quebec Heart and Lung Institute and their colleagues studied 1,387 patients who underwent bioprosthetic aortic valve replacement and found that hemodynamic valve deterioration identified by Doppler echocardiography occurred in one-third of patients and was associated with a 2.2-fold higher adjusted mortality. Diabetes and renal insufficiency were associated with early hemodynamic valve deterioration whereas female sex warfarin use and stented bioprosthetic valve versus the stentless ones were associated with late hemodynamic valve deterioration. These findings suggest that following bioprosthetic valve replacement, a systematic echocardiographic follow-up may be considered to ensure adequate detection and quantitation of hemodynamic valve deterioration.
That wraps up on the summaries this week. Now for our feature discussion.
We are recognizing the critical role that cardiac troponins play for the early diagnosis of acute myocardial infarction. We also know that there are different isoforms of cardiac troponins, the cardiac troponins T and I. Now, have you ever considered combining the two? How does that help the early diagnosis of acute myocardial infarction? Well, I am delighted to have with us the corresponding author of our feature paper today, Dr Christian Mueller from University Hospital Basel in Switzerland, a very familiar voice on this podcast. Welcome, Christian, and thank you so much for publishing yet another wonderful paper with us.
Dr Christian Mueller: Thank you very much for highlighting this important work and allowing me to comment on it in the podcast.
Dr Carolyn Lam: Christian, first of all, could you paint the background to help us understand what's the difference between the two isoforms, I mean, in terms of diurnal variation, the way that they may be released earlier or later, the way they may or may not be impacted by comorbidities like renal dysfunction or hemolysis? Could you help us understand why there may be rational to combine the two in looking at their impact on the diagnosis of acute myocardial infarction?
Dr Christian Mueller: The measurement of cardiac troponin as a structural protein unique to the heart clear is a central piece in our early diagnosis of acute myocardial infarction, so both for the early rule out in patients who present with chest pain and are finally found to have more benign disease as well as the early ruling. In general, I think it's important to highlight that there are two isoforms exactly as you have mentioned, so there is cardiac troponin T and cardiac troponin I. So these two proteins are cardiac specific and are used in the diagnosis of acute myocardial infarction. Now with the development of high-sensitivity methods or measurements of both cardiac troponin T and cardiac troponin I concentrations, we have been able to get a little bit of a better understanding of in fact differences in the pathophysiology as well as analytical details between cardiac troponin T and I.
Before I start highlighting the differences, I think it's important, I mean, both signals show a very strong correlation, so still very, very similar to each other. However, the small differences that have begun to emerge kind of allow to suggest that possible we could use them together as two pieces of information in the diagnosis.
So, what are the differences? First, exactly as you have highlighted, that if in fact that diurnal rhythm with cardiac troponin T, which means that cardiac troponin T concentrations are higher in the morning hours as compared to the evening, we still have no clue why that's the case, but it's a relevant difference about 25% and it has been shown in two cohorts and a group from Maastricht who was the first one highlighting this. This rhythm has not been found for cardiac troponin I. The second difference is that, again, probably understood in many, many population studies cardiac troponin T concentrations are even stronger predictors of death as compared to cardiac troponin I concentration. Then the third difference it seems that if we measure it with high-sensitivity assays, for example high sensitivity, it seems to rise or if you released from injured cardiomyocytes even slightly earlier as compared to T and possibly even less injuries necessary to release I as compared to T.
Then you mentioned renal function. Cardiac troponin T concentration shows slightly higher correlation with renal function as compared to I. Also, other pre-analytical issues, hemolysis seems to affect T and I concentration in a different way. So a lot of small tiny differences that have emerged and that underlie the hypothesis that possibly by combining the two signals we could be even more accurate in the diagnosis rather than relying on one on its own.
Dr Carolyn Lam: That's good. That really sets up the rational very well. I think in and of itself is a learning lesson, because I think most clinicians sort of take the two equivalently. So could you tell us what you found?
Dr Christian Mueller: I would like to of course thank the fantastic team that has allowed us to generate this data. It's a collaboration between the APACE investigators, the ADAPT investigators and experts in clinical chemistry from Maastricht University and Noreen Fandalin and Karen Villa of the first office. So we used two large diagnostic studies, APACE and ADAPT. We measured high-sensitivity cardiac troponin T and I and both of them and compared the diagnostic performance as compared to the final adjudicated diagnosis by two independent cardiologists who, of course, had all information, cardiac imaging and whatever you need to adjudicate.
So, what we found is that in general if you look at diagnostic accuracy, overall is quantified by the area under the curve. Combining the two signals did not consistently increase overall diagnostic accuracy as compared to the individual isoforms. However, we were able to document some improvement for the rule out for the very early rule out of acute myocardial infarction. So the concept that is extremely attractive of course from a medical as well as from an economic perspective is to rule out the presence of acute myocardial infarction with a single blood draw. So, we can do this if we assess the ECG. The ECG doesn't show relevant changes. Then if the troponin concentration measured with a high-sensitivity assay is very low, then the likelihood that the patient would have an acute myocardial infarction again is extremely low or in scientific term sort of a negative predictive value approach is 99 to 100%. By combining very low concentration for high-sensitivity T and very low concentration for I, we were able to increase the efficacy of the early rule out and that seemed to be the most likely possible clinical utility of combining the two signals.
Dr Carolyn Lam: Even that so-called neutral findings are very important. It's an important question to ask and important answer to get. Could you give us an idea for the rule-out part? How much do we gain? How much exactly do we gain by using both assays instead of just one?
Dr Christian Mueller: So, the efficacy of the early rule-out depends to some extent on the assay used and the cut off applied. So the current you see algorithm uses cut-off that has been shown to be very safe. However, they are regarding their efficacy not very high. So the current you see recommended cut-offs and approach, allows the rule-out only in about perhaps 10 or 15% of patients. That number can be significantly increased, likely doubled or perhaps even increased threefold by using the combination approach. So this has been consistently showed both in the derivation and the validation cohort.
Dr Carolyn Lam: Yeah. Do you think this is ready for prime time? I noticed a very balanced discussion actually calling for future studies, but perhaps you could state it better now.
Dr Christian Mueller: The main limitation regarding prime time is the fact that currently manufacturers either of a high-sensitivity TSA or of a high-sensitivity high method, which means that the vast majority of hospitals at this point in time do only have one method available. It would require quite substantial investment in both hardware as well as changing of the logistics in the lab to implement measurement of both assays. So I think it's likely feasible, but it would be associated with relevant investment from a hospital perspective. In addition, I mean, also the rule-out approaches that use of only one assay also there are studies ongoing in trying to further increase the efficacy of the single marker approach. So I think it's the best tool marker strategy that we were able to come up with recently, because many of the other biomarkers that we had tested really didn't work out. Still, as you mentioned, I think it's also important to be very, very honest that it will be difficult to implement tomorrow in most institutions.
Dr Carolyn Lam: Yeah, and perhaps a little bit more work needs to be done to sort first identify perhaps special situations where these may be particularly helpful. I supposed like you just said when we're thinking of the ESCs to review one-hour type algorithm, who knows maybe we should be having that extra insurance of the second test in those that test it negative in the first or something like that. Do you plan further work? I always ask you because you're always in the forefront of these things and we just love touching your work.
Dr Christian Mueller: We have several additional analyses ongoing. Again, I think the main part is for just to go ... I go back from a clinical perspective. So I think for many hospitals that are using T at the moment, it's important to have I available for certain situations. So for example if you have a patient in whom you have evidence of chronic skeletal muscle disease, most of these disorders are rare but some of them have been shown to be associated with increasingly highly troponin T that do not seemed to be related for cardiac diseases but from skeletal muscle. This is rare but if you have a patient with that kind of history, then the dual mark measurement is I think mandatory.
The same applies to iso that the other reasons to have false positive results for iso whenever you are ... If your hospital is using I, you should have the T method also available because once in a while you will identify patients in whom you have an I result that doesn't really match the clinical setting, then it's so easy and often so helpful to get the T result to decide on the most appropriate measurement of patient.
For which patients are kind of a standard that measures T and I would be justified, I think that's something to tease out in future study. I think that the rational is there and likely it will depend also on kind of which T or which I method we might use in the future. So at the moment, we have one method for high-sensitivity T, but there are several other methods in development and kind of applying for FDA approval for high-sensitivity I and possibly combination of these might be even more beneficial regarding the single measurements and I think that has to be teased out in future studies.
Dr Carolyn Lam: Exactly, but what great insights for us to consider as clinicians now for specific cases where we may consider find those if we have those in our institutions. At the end of the day, I supposed cost-effectiveness analysis will need to be done. Agree?
Dr Christian Mueller: Absolutely, absolutely. The good thing about troponin, it's extremely inexpensive. So as compared to most of the new fancy biomarkers that are usually, rather prices of troponin is a routine marker. It's inexpensive. It's there for very likely that if we are able to document some clinical value that also the cost-effectiveness study that's definitely unnecessary will show also some economic benefit.
Dr Carolyn Lam: Oh, Christian, thank you for publishing yet another impactful and clinically relevant paper with us here in Circulation. I mean, it's exactly the kinds of papers that we really treasure here, because they directly inform clinicians and open our eyes to actually things that we should be considering in our everyday practice. Clod I ask you maybe cheekily to share about your experience with publishing at Circulation? Someone like you will be the best person to tell the world what it's like.
Dr Christian Mueller: Oh, of course. I mean, for us as a research group and for me as a researcher, it's fantastic. It's perfect to have some of our work published in Circulation that has fantastic impact factor, fantastic readership and ensures that the research catch the attention that's fantastic. Also, I think for us as a research group, the recognition of being able to publish in Circulation is outstanding and it helps us continue in the research group that we do. The comments made to large extent also by the editors. Also, on this manuscript, I think we're incredibly insightful and definitely had a major contribution to the final product to make it as attractive and also as balanced and insightful I think as it is at this point in time.
Dr Carolyn Lam: Thank you so much for providing that feedback, because it is our aim, explicit aim to put a partner authors in getting the best of the manuscript and working really closely with you. So thank you once again, Christian, for your time today. Audience, I know you've heard many times from this favorite person that we have on our podcast.
Do share this podcast with all your colleagues and don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the Journal and its editors. I'm Dr Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore.
Do we finally now have a simple, evidence-based way to make a diagnosis of heart failure with preserved ejection fraction? Well, today's feature paper certainly brings us closer to that goal and you must listen to the discussion coming right up after these summaries.
Bleeding is commonly cited as a reason for stopping oral anti-coagulants. However, what is the prognostic significance of minor bleeding events, or so called nuisance bleeding, in patients with atrial fibrillation on oral anti-coagulants?
First and corresponding author, Dr O'Brien from Duke Clinical Research Institute and her colleagues, identified 6771 patients with atrial fibrillation in the Orbit AF Prospective Outpatient Registry. They ascertained nuisance bleeding from medical records defined as minor bleeding that did not require medical attention. Overall, 20% had documented nuisance bleeding giving an incidence rate of 14.8 events per hundred person years. Nuisance bleeding was not associated with a higher risk of major bleeding, or a stroke and systemic embolism over the next six months.
These findings therefore suggest that the occurrence of nuisance bleeding or minor bleeding should not lead to changes in anti-coagulant treatment strategies in patients treated with anti-coagulants.
The next study sheds new light on mechanisms linking NLRP3 inflammasome activation to atherogenesis. Dr Westerterp from Columbia University, New York and colleagues studied mice with myeloid deficiency of ATP binding cassette transporters A1 and G1 and concomitant deficiency of the inflammasome components NLRP3 or caspase-111.
They showed that cholesterol accumulation in myeloid cells activated the NLRP3 inflammasome. NLRP3 inflammasome activation enhanced neutrophil accumulation and neutrophil extracellular trap formation in atherosclerotic plaques thus accelerating atherogenesis.
Patients with Tangier's disease, who had ATP binding at transporter A1 loss of function, had increased myeloid cholesterol content and showed markers of inflammasome activation. Thus, inflammasome activation may underline cardiovascular disease in these patients.
The next study identifies TPX20 as a novel transcription factor regulating angiogenesis. TPX20 is a crucial transcription factor for embryonic development and its deficiency is associated with congenital heart disease. However, its role in angiogenesis has been not been previously described. At least until today's paper from co-first authors Dr Meng and Dr Gu and co-corresponding authors Dr Cooke and Dr Fang from Houston Methodist Research Institute.
These authors use loss and gain function approaches to explore the role of TPX20 in angiogenesis both in vitro and in vivo. They showed that with VEGF stimulation, the transcription factor TPX20 upregulated PROK2 with is secreted from endothelial cells and gauges its receptor PROKR1 and thereby promotes angiogenesis in autocrine manner.
This novel signaling pathway appeared to be highly conserved as it functioned in zebra fish vascular development and the angiogenic response to ischemia in a mouse model of peripheral disease. The authors furthered showed the selective role of TPX20 in endothelial migration but not proliferation. Furthermore, treatment with recombinant PROK2 the critical effector of TPX20, improved blood profusion and functional recovery in the mouse peripheral artery disease model. Thus, these data highlight the therapeutic potential of PROK2 in augmenting functional angiogenesis for diseases associated with this regulated angiogenesis.
In patients with atrial fibrillation, left atrial appendage closure with the Watchman device, is known to prevent thromboembolism from the left atrial appendage. However, thrombus may still form on the left atrial face of the device, which then may potentially embolize. This next paper provides important data on the incidents, predictors, and clinical outcomes of device-related thrombus after left atrial appendage closure.
First author, Dr Dukkipati and corresponding author Dr Reddy from Icahn School of Medicine at Mount Sinai, New York and their colleagues studied the device arms of 4 prospective FDA trials of patients undergoing the Watchman implantation. These were the PROTECT AF, PREVAIL, CAP, and CAP2 trials.
They found that following percutaneous left atrial appendage closure with the watchman device, the incidence of device-related thrombus was 3.7% and this was associated with a more threefold higher risk of stroke and systemic embolism. Predictors of device-related thrombus were a history of trans- ischemic attack or stroke, permanent atrial fibrillation, vascular disease, a larger left atrial appendage diameter, and a lower left ventricular ejection fraction.
Device-related thrombus was not associated with an increased risk of cardiovascular or all-cause mortality. Nearly 75% of patients that developed device-related thrombus did not experience a stroke. And ischemic strokes occurring in patients with device-related thrombus accounted for approximately 10% of all ischemic strokes, following left atrial appendage closure. Thus, given the ramifications of device-related thrombus, a judicious surveillance strategy using periodic transesophageal echo cardiography may be considered particularly when risk factors for device-related thrombus are present.
Well, that wraps it up for our summaries. Now for our feature discussion.
Heart failure with preserved ejection fraction or HFpEF, notoriously difficult diagnosis to make, but do we finally have a validated diagnostic algorithm for HFpEF? Oh, you have to listen to our conversation today. I am so proud and pleased and thrilled frankly to have with me today the corresponding author of the feature paper, and that's Dr Barry Borlaugug from Mayo Clinic in Rochester, Minnesota as well as editorialist Dr Walter Paulusus from VU University Medical Center in Amsterdam.
Thank you so much both of you for making it here. I want to dive straight into it. So, Walter, maybe could you please paint the background to this because you wrote I think the most highly cited diagnostic guidelines of HFpEF, but that was in 2007. Tell us how does today's paper take us forward?
Dr Walter Paulus: Thank you very much, Carolyn. It's quite an honor for me to give you comments about this paper, which I think is going to be a landmark event. Over the years we have seen multiple algorithms being proposed usually by professional societies like V and C or the American Society of Echocardiography for the diagnosis of HFpEF. The major drawback of all these algorithms is that they have never been validated in clinical practice. And the reason they have never been validated was that it was extremely difficult to establish a gold standard for HFpEF.
And Barry was so clever to already invest in an establishing a gold standard for HFpEF ten years ago, and he very vigorously subjected all his patients in whom he suspected HFpEF to an invasive stress test and could establish the diagonals of HFpEF using this as a gold standard. And then he used all these consecutive patients with subsequently used to devise some form of an algorithm that was immediately validated against a gold standard. I think this has been a giant leap forwards. And again, I want to congratulate him with this unique endeavor.
Dr Carolyn Lam: Barry, I want to echo Walter's words and congratulate you. Now, has it really been ten years in the making? Tell us about this, Barry.
Dr Barry Borlaug: It has. In fact, it was 12 years ago when we started doing this, in 2006. But, yeah, these patients were examined in our laboratory between 2006 when I joined the staff at the Mayo Clinic to 2016. And really just doing this work up, we kind of started out doing it on a few patients and then we realized how powerful the methodology was. We did the invasive exercise testing with hemodynamics and a larger number of patients and just through accumulating a large number, as Walter points out, with a gold standard assessment this allowed us to then determine which less invasive attributes could be used to identify the likelihood that heart failure was the diagnosis.
Dr Carolyn Lam: That's so great. But you know beyond just that it is such a precious data set and so on, your paper is just so beautifully written and so clinically applicable. You've got this HFpEF score now for diagnosis. Everybody's going to be talking about it. So tell us about it. What does HFpEF score? What makes you think it'll work? How do you apply it clinically?
Dr Barry Borlaug: Thinking about diagnosis a lot, you really have to go back to [00:19:19] thinking, estimating the probability of disease, and when you're able to do that then you can find people where you need to perform really more invasive testing like the exercise testing. So really, we started like we need to have a better way to define who needs that more expensive and invasive evaluation. So we have this large cohort of patients, over 500 patients, 414 in the initial cohort, and then another 100 in the validation cohort. And they had all undergone this work up, they'd all undergone very detailed clinical evaluation and pheno typing. And we hypothesized which characteristics we thought would be most relevant. And then we did logistic regression to identify all the predictors.
There were many things that are associated that you would expect with HFpEF, but there were only 6 factors in the end in a multi-variable model that were all independently associated. That provided the most parsimonious sort of model or score that we could develop. We included these six different variables. So there's two for letter H- heavy and hypertensive, and by heavy we define that as a body mass index above 30. Hypertensive is defined as two or more antihypertensive medicines. The F in the H2 HFpEF score is atrial fibrillation, either paroxysmal or persistence a. Fib. The P is for pulmonary hypertension as estimated by echo with an estimated PA systolic pressure on echocardiography of 35. We wanted all of these to be noninvasive criteria for this score. E is for elder. I specifically didn't call it elderly because that can be a pejorative term and its only 60 years which is not that old. So E is elder. And F is for filling pressures, again estimated by echo doppler cardiography as an EE prime ratio greater than 9.
All of the scores are not one point each. They were arranged based on the strength of correlation in the logistic model. So being obese, having a BMI above 30 was awarded two points because it has a strong correlation. Being in atrial fibrillation or having a history of atrial fibrillation was even stronger at three points. If you tally these up, the score can range from 0-9, and based on that score you can then estimate a probability that HFpEF is present, if you're evaluating a patient that meets the entry criteria of the study, which is basically normal ejection fraction, and exertional breathlessness.
Dr Carolyn Lam: Nice. Okay, Walter, I think I can safely say that you have been thinking about this syndrome longer than either Barry or I. So I'd love your perspectives on how do you think this will be put into practice clinically perhaps, and where is the key area that it will change practice compared to perhaps the old diagnostic algorithms were like?
Dr Walter Paulus: I think this is a very important point, Carolyn. I think this score is so easy to handle and it is so well validated that we can now go to general practitioners and cause a general awareness for the disease. What vies me is that many patients are still unreported. The reason is that general practitioners and even general internal medicine people do not realize the [00:19:19] heart failure with preserved ejection fraction. Now with this score at hand, we can convince them that there needs to be an awareness when they see people that have value higher than six on the score, that they should be suspicious of heart failure being part of the symptomatology. I think this score mainly has its usefulness for general practitioners and general internal medicine.
Apart from the score, and it's more up to Barry to comment on this, but I want to highlight also, that he did not only develop the score, but he also had these very beautiful nomograms which is more of a find than a score, where he treated the variables in a continuous way. I think this is fairly useful for cardiologists and especially for people who want to have acute patients into trials because here we now have a very refined scale that goes from 0-160 and that allows you again to see what type of population you are addressing, what type of patients you are seeing that eventually what type of patients you are recruiting. I think for me the HFpEF score is of importance for general practitioners, general internal medicine, and especially I think we should also promote the nomogram. The nomogram, I think, are so refined that it would be useful tool, I think an excellent tool, for includement into trials.
Dr Carolyn Lam: Oh wonderful. Both of the simplicity and the cleverness, if I may, of this paper are precious to generalists and cardiologists. But Barry, I do have a couple of questions for you. Both you derivation and validation were in Olmsted if I'm not wrong. Now how am I supposed to apply it to my skinny HFpEF patients in Asia or elsewhere?
Dr Barry Borlaug: That's an important point, Carolyn. And it's a limitation of the paper. The people in Olmsted County, MN are not the same as they are in other parts of the United States or other parts of the world. I think that additional evaluation and other cohorts are important. We did the best we could with what we had. We did look at the patients carefully at Mayo Clinic. People think of it as quaternary referral center, but a pretty substantial number of the patients are from the local area, I think about 2/3 of them were. And when we looked in a subset in a sensitivity analysis of the people that were more local practice rather than coming from large academic medical centers, the HFpEF score, or as Walter pointed out, the continuous HFpEF model performed equally well. When we looked at people with so-called advanced HFpEF so high hemopressures at rest versus people at so called early stage HFpEF the people that have normal hemodynamics at rest but elevation during exercise. The model also worked well in that cohort.
But, like most studies that come out of where I work in southeastern Minnesota, it is mostly Caucasian people, the mean BMI was in the low 30s. So we need to look at other populations to make sure this works elsewhere as well.
Dr Carolyn Lam: Barry, let it go on record that I am your biggest fan. So thank you so much for this. I was just thinking even in other populations where the mean BMI may be lower for example here in Asia, we still definitely see an association with a higher BMI albeit at a lower cutoff with the presence of HFpEF. So it does raise this issue of do we need to maybe calibrate the score differently in different geographies or ethnicities. But that's not by any way take away from the tremendous input that you've made.
One other question is also the strength of atrial fibrillation in impacting the score. What are your thoughts on the possibility of misdiagnosis for example atrial fibrillation as HFpEF or the similar situation since they share symptomatology?
Dr Barry Borlaug: This is a great point, Carolyn. People still sort of argue about this. Somebody has breathlessness and effort intolerance and atrial fibrillation. Some doctors say they have symptomatic atrial fibrillation, but when we put catheters when we take these patients to the so-called table of truth and put catheters in and exercise them, we see hemodynamic arrangements that are diagnostic of heart failure. This led us to believe that this isn't just symptomatic a fib. It's really HFpEF. And that's why they have a fib. We published a paper earlier this year in circulation, more of a brief report, on the association between atrial fibrillation and HFpEF where we first reported this. That if you have normal EF, and especially permanent atrial fibrillation, you can pretty much take it to the bank that the patient probably does have heart failure with preserved ejection fraction, at least in the way that we have sort of defined it and the way that [00:19:19] initially defined it as an inability of the heart to pump blood adequately at normal filling pressures.
These patients almost all have that criteria for cardiac failure. I think that it is a really strong indicator and we probably are really just like in the general clinics, under recognizing HFpEF. I think probably in other clinics where people have atrial fibrillation and effort intolerance, we're again really under recognizing HFpEF in these people.
Dr Carolyn Lam: Indeed, and it's actually very consistent with Walter, your recommendations where atrial fibrillation played a big part too. Do you have any thoughts or advice?
Dr Walter Paulus: My idea is that atrial fibrillation and HFpEF are both manifestations of the same underlying process, which is systemic inflammation because of a metabolic disturbance. We used to think of atrial fibrillation as a consequence of left atrial dilatation, which itself was caused by the high filling pressures. I think that this does not hold, there is more to it. I think the atrium is as sick as the left ventricle and it undergoes similar pathological changes. That's why the presence of a fib becomes such a strong determinant of the presence of HFpEF in Barry's H of HFpEF score. All of this makes a lot of sense to me.
I just want to add something else. You spoke about the Asian population having less BMI and already having HFpEF. I think if you look at Barry's variables in uni-variant analysis, there's one which was presence of diabetes or prediabetes which did not make it in the multi-variant analysis on 0.06. It's my belief that if you got to the Asian population, that probably the BMI could be replaced with the presence of prediabetes and diabetes. Usually the insulin tolerance or insulin resistance is presence and the BMI is still low. I think there is need for some fine tuning, maybe in Asian populations, and I think this should be a challenge to go ahead with it. In fact, I'm leaving for Japan the day after tomorrow and I'm going to show the slides of Barry's paper. I'm going to try to set something up to also validate the score in Japanese populations.
Dr Carolyn Lam: We've got our work cut out for us, Barry! Let's get on to this too in southeast Asia.
Dr Barry Borlaug: I totally agree with Walter. I think that's great. And Carolyn, you, in a lot of papers, point this out, that the metabolic, cardio-metabolic associated with excess body mass, the way we define it with BMI, is shifted way down in southeast Asian population, and south Asian population, so I would agree with Walter's hypothesis that diabetes, prediabetes maybe that's the better way to go when we look at this in other patient populations.
Dr Carolyn Lam: You both absolutely made my day with this discussion today. Thank you so much. What a thrill to be on the same podcast with the people I admire most.
Listeners, I know you enjoyed this as much as I did. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and it's editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
Can we get better at predicting clinical benefit of PCSK9 inhibition based on the severity and extent of coronary artery disease? Well coming right up after these summaries we have an important discussion of an analysis from the FOURIER trial, so stay tuned.
The first original paper this week suggests that targeting visceral adiposity may be the crucial step to limit age-related cardiac remodeling and to promote healthy cardiac aging. Co-first authors Drs Sawaki and Czibik, corresponding author Dr Derumeaux, from INSERM France, and their colleagues, hypothesize that since aging induces cardiac structural and functional changes, linked to increase deposition of extracellular matrix proteins including osteopontin, well osteopontin may play a role in myocardial aging.
To test this hypothesis, they studied osteopontin-deficient mice and their wild-type litter mates at two and 14 months of age in terms of cardiac structure, function, histology and key molecular markers. They found that during aging, visceral adipose tissue represented the main source of ostepontin and altered heart structure and function via its profibrotic secretome. Furthermore, interventions targeting osteopontin, such as visceral adipose tissue removal and osteopontin deficiency, rescued the heart and induced a selective modulation of fibroblast senescence. This work uncovers ostepontin's role in the context of myocardial aging and suggests that osteopontin may be a potential new therapeutic target for a healthy cardiac aging.
The next study shows that higher triglyceride rich lipoprotein cholesterol may be a risk factor for cardiovascular disease and potential therapeutic target. First author Dr Vallejo-Vaz, corresponding author Dr Ray from Imperial College London, and their colleagues assess the relationship between triglyceride-rich lipoprotein cholesterol and cardiovascular risk and whether this risk was modifiable among patients receiving statins in the TNT trial. They found that higher levels of triglyceride rich lipoprotein cholesterol were associated with a significantly higher rate of cardiovascular events among coronary patients treated with statins. Statin therapy reduced triglyceride-rich lipoprotein cholesterol and to a greater extent among those treated with a higher statin dose.
Based on their post hoc analysis of the TNT trial, they found that more intensive statin therapy with atorvastatin 80 milligrams, compared to atorvastatin 10 milligrams, resulted in a significantly greater cardiovascular risk reduction among patients with higher triglyceride-rich lipoprotein cholesterol. These results were consistent for higher triglycerides and directionally concordant for non-HDL cholesterol. A higher percentage reduction in triglyceride-rich lipoprotein cholesterol was associated with lower cardiovascular risk independent of LDL cholesterol reduction. Thus, these findings suggest that triglyceride-rich lipoprotein cholesterol is not only a cardiovascular risk marker, but also potentially a therapeutic target.
Late gadolinium enhancement on cardiac magnetic resonance imaging represents fibrosis and is seen in 60% of adult patients with hypertrophic cardiomyopathy. However, what about in children and adolescents with hypertrophic cardiomyopathy? First author Dr Raja from University of Copenhagen in Denmark, corresponding author Dr Ho from Brigham and Women's Hospital in Boston, and their colleagues looked at cardiac magnetic imaging data from 195 children and adolescents with hypertrophic cardiomyopathy. Late gadolinium enhancement was present in 46% of patients with overt hypertrophy as opposed to 60% typically represented in an adult population of hypertrophic cardiomyopathy. On the other hand, late gadolinium enhancement was not seen in mutation carriers without left ventricular hypertrophy.
In patients who underwent serial imaging, increases in late gadolinium enhancement, left ventricular mass, and left atrial size were detected over two and a half years. Thus these findings in children provide additional insights into the biology and natural history of hypertrophic cardiomyopathy and confirmed that fibrosis is a significant part of the disease process in both children and adults.
Whether the adult mammalian heart harbors cardiac stem cells for the regeneration of cardiomyocytes is an important yet contentious topic in the field of cardiovascular regeneration. This week's paper adds to the growing knowledge in this area. First author Dr Li, corresponding author Dr Zhou from Chinese Academy of Sciences and their colleagues developed a new genetic lineage tracing system to label all nonmyocyte populations that contain putative cardiac stem cells. Using dual lineage tracing system, they assessed if non-myocytes generated any new myocytes during embryonic development, adult homeostasis and after myocardial infarction. Skeletal muscles were also examined after injury and acted as internal controls.
By using this stem cell marker free and dual recombinases mediated cell tracking approach, the author showed that new myocytes arose from nonmyocytes in the embryonic heart, but not in the adult heart during homeostasis or after myocardial infarction. As positive controls, the same lineage tracing system detected new myocytes derived from nonmyocytes in the skeletal muscle after injury. Thus, this study provides in vivo genetic evidence for non-myocyte to myocyte conversion in the embryonic but not the adult heart. This study also provides a new genetic strategy to identify endogenous stem cells, if any, in other organ systems for tissue repair and regeneration.
Well, that wraps it up for our summaries this week, now for our feature discussion.
Are there subsets of patients that derive greater clinical risk reduction with the PCSK9 inhibitors? Well we're gonna find out about that right now with a discussion of our feature paper entitled the “Clinical Benefit of Evolocumab by Severity and Extent of Coronary Artery Disease.” So pleased to have with us Dr Marc Sabatine from the TIMI Study Group, who is the first and corresponding author of today's feature paper, as well as our editorialist, Dr Roger Blumenthal from Johns Hopkins University. And of course, we have a familiar voice, a very important editor of our digital strategies and that's Dr Amit Khera from UT Southwestern.
Welcome everyone, I think I'd really like to start with maybe asking Roger to paint the background of the importance of this paper. Simply because I just love the title of your editorial, which is “Realizing the Value of PCSK9 Inhibitors: Are We Closer to Finding the Sweet Spot?” I think that really encapsulates it. So Roger, your thoughts?
Dr Roger Blumenthal: As Amit Khera knows, I'm a golfer, so when you think about the sweet spot on the club, and we know that PCSK9 inhibitors are a great story of translation from bench to bedside, and we also know that the high cost of the therapy presents a challenge. So what Dr Sabatine and colleagues did was to try to identify the sweet spot for its most effective use and that was a pleasure to comment on Dr Sabatine's excellent study.
Dr Marc Sabatine: I think taking a step back I would say from pure biologic perspective, we know that lowering LDL cholesterol will reduce events and that's true and primary and secondary prevention and so if you have therapies that were safe and inexpensive, then I think you wouldn't need to really look for that sweet spot cause it would be all sweet if you will to extend the analogy. But Roger's absolutely right that when you have therapies that are then expensive, then you have to decide, okay in which patients will I get the biggest bang for my buck? And that's a very legitimate question to ask.
And so in FOURIER, overall the trial was positive but as we look for subgroups we say, "Can we find individuals who enjoy a greater absolute risk reduction?" Because therefore the benefit cost ratio is gonna be particularly favorable. And so we approach that in a couple different ways. First you can look for just predictors of baseline risk, so if someone has twice the baseline risk and the same relative risk reduction, you should get about twice the absolute risk reduction and therefore the number needed to treat would be cut in half. And so based on our experience from other TIMI trials and other datasets, we looked at three features that have identified patients with higher baseline risks.
Amongst those with a history of MI which is in and of itself a heterogeneous group. And so those features were patients with a more recent MI, those with multiple prior MIs and those with known residual multivessel coronary disease. And all three features in the FOURIER dataset, not surprisingly, were predictors of risk with patients having an average about a 50% higher baseline risk. But what was particularly nice was that the subgroups also identified patients who had greater relative risk reduction. And so when you couple the two, the higher baseline risk with the greater relative risk reduction, that translated into greater absolute risk reduction then in each of these high-risk groups, the absolute risk reductions over three years or for CV death, MI, and stroke was around 3% versus around 1% for the low-risk groups.
And so that changes the number needed to treat by a factor of three.
Dr Carolyn Lam: Wow, that's so cool. Amit, do you think you could just give us a sneak peek into the editors’ discussions when you saw this paper?
Dr Amit Khera: This was an easy one, it's clearly a very important paper and if you step back 10,000-foot view, these drugs were initially approved based on LDL lowering and people were using them without knowledge of whether or not they actually lowered events. Marc's group and others have now shown us that certainly they do lower events, but really the next most important thing is application. Who should we use them in and when should they be used and where might they be most effective and I think it was said out in the introduction of this paper, this idea of personalized medicine. And I think this really is an important step forward, not just for PCSK9 field but in general, how we should be thinking about drugs, about balancing cost and benefits and who would benefit most.
So maybe one analogy, I think PCSK9 was not prescribed as much as they had been predicted given costs and other considerations and maybe with analysis like this they've hit it out of the rough back on the fairway, I threw that in for you, Roger. And I do have one question for Marc, which is this is clearly important to better define who would benefit the most and I guess in terms of action abilities, the goal here to provide guidance for clinicians where, you know, if I'm seeing a patient this morning I would take this into account or is this something larger where we recently saw with alirocumab, they changed pricing based on sub-group analysis of a higher risk group. How do you think we should move forward with this type of information?
Dr Marc Sabatine: I’ll get back to the point I raised earlier, I do want to underscore that I think that the true biologic notion is that all these patients, sub-types of secondary prevention or primary prevention all benefit from LDL lowering. So I wouldn't want people to walk out with the notion that it's the only subset that would benefit and really from a population level, obviously Roger's in a better position to speak about this, but sort of shifting the population LDL lower in general would have a huge impact on the risk for cardiovascular disease. But to your question Amit, looking in for a patient in front of you, I think it's quite fair to say right now there's this kind of tug of war back and forth between payers and clinicians.
Clinicians saying, "I have a patient in front of me, they have known atherosclerotic cardiovascular disease, I wanna lower their risk, I wanna manage their risk factors and I wanna get their LDL cholesterol lower and I have a bunch of great tools in front of me." Statin for sure is the foundation, maybe acetamide and PCSK9 inhibitors. And then payers saying, "Well wait a minute, these are expensive drugs and so we're gonna try to restrict that and create a lot of hoops for clinicians to jump through." And so I would rather than wasting all that time back and forth, I think it is logical to say, "What are the high-risk groups?" Where we can agree there's the large enough absolute risk reduction that for a given cost, that makes sense.
Allow there to be alignment for that and have clinicians just be able to write a script and have it filled rather than wasting a lot of time with preauthorization and letters back and forth.
Dr Amit Khera: That's a great point, maybe I'll just take one follow-up, which is now trying to sift through all the high-risk groups and they end up maybe becoming a bit of a Venn diagram. I know in Roger's editorial he talked about the other FOURIER analysis with PAD and there's more groups to come or do we have enough of a starting place where we think we have enough for decision making?
Dr Marc Sabatine: I would say there are a variety of groups, there is some overlapping even in the paper then we looked at the union of those three high-risk features, which identified about two thirds of the patients who were enrolled in the trial with a history of MI. But you're right, the other slices of the data that will also identify high risk groups, PAD is a particularly good one because most of the therapy for those patients has focused on antithrombotic therapy, which always will have some downside for increased bleeding, whereas risk factor modification in this case has no downside. So that's a very high-risk group, it certainly is important to focus on. But I think within the MI subset, this is a great place to start the other analyses we're doing.
And probably after we've sort of finished the series of, if you will, these kind of univariant slices, then we'll try to put that together into a more comprehensive picture.
Dr Roger Blumenthal: We tried to say that we still need the formal cost-effective analyses in these specific high-risk groups, but it seems most reasonable to focus on engaging in shared decision making now with our patients about PCSK9 inhibitor use and those with a recent ACS and the basis of Odyssey Outcomes and we're awaiting the final publication of that. Symptomatic peripheral arterial disease, which Marc previously published in Circulation, and then looking at these high-risk features that was the subject of this article, those with a more recent MI within the past two years, multiple prior MIs and residual multivessel coronary disease.
And one of the things that we especially found interesting was among the more than 8,000 individuals without a high-risk feature, the event rates were nearly unchanged in the evolocumab versus placebo groups. So I think that's very important, but one other point that we have to keep in mind is that the focus of the last set of guidelines and probably the next cholesterol guidelines that likely will be out in November, will have a large component of the shared decision making and we need to see where the cost comes down, whether these companies that make these medications will be able to significantly lower the cost in a reproduceable manner and patients and clinicians will have to jointly decide what to do, do we add acetamide? Do we add a PCSK9 inhibitor?
But we finished our editorial saying that all clinicians and patients should currently pursue a comprehensive lifestyle and medical regimen for secondary prevention. We all have to remember that and if a person's LDL, a high-risk individual is at least 70 with high-risk features and certainly above 100 on maximum tolerated statin therapy, it's important to strongly consider a PCSK9 inhibition and it'll be very interesting to see what the final wording is when the ACC/AHA cholesterol guidelines come out in November.
Dr Carolyn Lam: Amit, would you like to add any further take-home for the clinicians listening in?
Dr Amit Khera: I just first want to congratulate both of these discussions today, I think the paper was so incredibly important and I think Roger's group really helped frame it well in the field. The one thing I'd say is this is a moving target, we have some early guidance now that I do think is actionable, so I actually have clinic in about an hour and I'm sure I'll be thinking about this as I think about how to apply PCSK9. Which groups might benefit most, so I do think this is actionable now, I think the points that were made about cost effective analysis, how do we bundle all these concepts or high risk patients into maybe an algorithm and how do the guidelines interpret this as a moving target. We'll wait to see, but I do think there's some important actionable information even now for our clinical patients.
Dr Carolyn Lam: I just love that, and you know that is just so much in line with the ethos of what Circulation is about now. We really, really love the papers that you have to pick up because they're of immediate applicability to your clinical practice.
Well audience, you heard it right here. Thank you so much for joining us this week and of course don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore. I'm the one you usually hear chatting about all the papers in your weekly issue, however I am so delighted to be handing over the mic this week to two beloved colleagues, and they are Dr Greg Hundley and Dr Vlad Zaha, who will be taking us through this week's very special issue centered around cardio-oncology. Here they are.
Dr Greg Hundley: My name is Greg Hundley. I'm a professor at VCU Health Sciences in Richmond, Virginia. We also have Vlad Zaha, who is an assistant professor at University of Texas Southwestern in Dallas.
Dr Vlad Zaha: Hello, everybody.
Dr Greg Hundley: We're going to be talking about the field of cardio-oncology today. As we all know, there have been many advances in the treatment of cancer lately, such that cancer is now becoming in some regards almost a manageable disease or a chronic disease for many individuals. But unfortunately we're seeing the emergence of cardiovascular disease in many patients, so much so that for some cancers, for example breast cancer survivors, cardiovascular events have supplanted the occurrence of cancer-related morbidity and mortality overall.
And so emerging today is this new field of cardio-oncology, which is really a bridging discipline between oncologists and cardiologists that have been focused almost on examining the relationship between chemotherapies, radiation therapies, newer targeted immunologic therapies on the development of cardiovascular events. We as cardiovascular medicine specialists often become involved and then we are consulted to see a patient that might be scheduled to receive a cardiotoxic therapy and what should we do. Maybe they've already received, they're in the middle of the therapy, and we're asked to provide guidance to help the patient move through that therapy successfully.
We're examining survivors now, those that have gone on the therapy and are experiencing increased cardiovascular risk. And then finally, a new emerging field that examines the association of risk factors that seem to be common between cancer and cardiovascular disease.
In this issue of Circulation there are theories, really a miniseries of manuscripts, that are at this interface between cardiovascular and oncologic science and medicine. Following a similar miniseries that we published in 2015, this new block of manuscripts looks on some of the risk factors and mechanisms that may be common between these disorders.
We're going to start today and look at this particular issue and examine the original manuscripts, look at the letters, and then talk a little bit about the review articles. I will walk through some of the introduction and then Vlad Zaha, who is working in cardio-oncology at University of Texas Southwestern, will help interpret for us some of the results and the meaning.
The first study, an original manuscript by Simes et. al that's a subanalysis of the lipid study, and that's the Long-Term Intervention with Pravastatin in Ischemic Disease. The study is going to examine the relationship between D-dimer and the future development of cardiovascular events, but also importantly, cancer-related events. Remember, D-dimer is the degradation product of cross-linked fibrin markers of hypercoagulation and thrombosis. We use this a lot in the emergency department as an identifier of those at risk when we're suspecting one of CVT, pulmonary emboli, etc.
This particular study focused on individuals aged 31 to 75 years that had experienced previously a myocardial infarction. The patients were randomized to receive 40 mg of pravastatin versus a placebo and as part of the study they were followed for six years to identify cardiovascular events. But at the end of the study another examination, an extended review, was enabled so that the patients or participants could be followed for another ten more years and in addition to looking at cardiovascular events, they also looked at all-cause mortality and etiologies of that mortality and specifically cancer.
Vlad, can you tell us a little bit about some of the results and what did D-dimer predict?
Dr Vlad Zaha: D-dimer has been considered a rather non-specific product that was first introduced in clinical practice in the 1970s for diagnosis of venous thromboembolisms. It is really interesting in this study that the others identified D-dimer that it is an independent predictor of not only long-term risk of arterial and venous events but all-cause mortality, cardiovascular disease mortality, cancer incidents and mortality and non-cardiovascular disease and non-cancer morality.
It raises interesting questions that are further explored in an editorial in the same issue about what is a low and what is a high D-dimer and also what drives the D-dimer generation in these patients.
Dr Greg Hundley: And so, it's interesting as well that one is identifying those at risk of cardiovascular disease but also cancer. Do the authors and the editorialists speculate on what that connection may be?
Dr Vlad Zaha: The question that is discussed is a common area of etiology that is being more and more discussed nowadays as bridging the domains of heart disease and cancer, and that is information. Information resulting then in alteration of the clotting cascade and hypercoagulability that may then influence downstream both atherosclerosis and cancer processes.
Dr Greg Hundley: Very good. It's interesting that we're bringing up this whole area of thrombosis because that really follows in the next study, which is a large population cohort assessment that is collected from a Danish registry of 6600 subjects that had experienced a lower extremity arterial, not venous, but arterial thrombosis. In that study what did they uncover, Vlad, in terms of an association with cancer and previously experiencing a lower extremity arterial thrombosis?
Dr Vlad Zaha: Another interesting study where the patients uncovered an increased risk of cancer compared to the general population, especially during the first six months before, the investigators identified an association between lower limb arterial thrombosis and increased all-cause mortality in common especially for the smoking-related cancers. This is a very interesting study that brings up the possibility of opportunistic screening, again focused on cancer-related signs and symptoms during the diagnostic workup for lower limb arterial thrombosis.
Dr Greg Hundley: And so, in these first two studies, both large in number, were identifying issues related to thromboembolic events and cardiovascular disease that also appear related or associated with the future development of cancer. The next couple of studies now switch and address issues related to mechanism. The first is a relatively large complex translational study by Meijers and associates that were examining the relationships between heart and vascular injury and the future development of colon cancer.
In this particular study there were two separate experiments, one group performed in mice and the other performed in analyses of serum and plasma that were collected from human subjects that had experienced colon cancer. In the first series of experiments in mice, the mice were induced myocardial infarction and then they were a strain that were somewhat predisposed to development of colon cancer. What the investigators did is they examined in this strain predisposed to the development of colon cancer, the impact of inducing a myocardial infarction and promoting heart failure versus those that were not and they identified what looks to be some sort of association between an increased risk of development of colon cancer.
Vlad, what were your observations and thoughts in terms of these particular findings and results?
Dr Vlad Zaha: This is an interesting paradigm of bringing basic science observations and testing them in a translational fashion. It is a combination of really elegant studies in a mouse model that identifies potential targets of clinical relevance in a model of myocardial infarction. The authors evaluate the fact that such molecules in human cell line models and test the proliferation in that environment. The question is then: How does this reflect in a cohort of patients? That, I think, is really the strength of the study to be able to show that some of the biomarkers identified which events can have an implication at the bedside.
Dr Greg Hundley: It was really interesting in that in the animals, independent of the hemodynamic compromise, so the hypotension, the reductions in EF, these circulating biomarkers that you identified seemed more associated with the development of colon cancer and then in the human study, examining similar factors were observed in patients with colon cancer and heart failure from the circulating blood of those individuals. Very interesting relationship identified in a very elegant translational study that involved both animal models and human subjects.
The second mechanistic paper is by Li and associates and it's really addressing the issue of anthracycline-related cardiovascular injury. Remember, we still utilize anthracycline chemotherapy today as a fundamental curative component of the therapeutic regimen for lymphoma, leukemia and sarcoma, also in those with triple-negative breast cancer as an important component of that regimen for adjuvant treatment. In this particular study, the investigators were examining the implication of phosphoinositide 3-kinase. That is an important enzymatic regulator of tumorigenesis, but it also when it's expressed is up-regulated during cardiac stress and really impacts adverse remodeling and promotion of heart failure.
In this particular study, the investigators in a mouse model were looking at blocking this particular enzyme and they had some really interesting results pertaining to the development of heart failure and cancer. Vlad, what did you see in this study that looked unique in that perspective?
Dr Vlad Zaha: This is an especially interesting study for the perspective of the oncologists who still have to prescribe anthracycline, given the uncertainty of early toxicity that can manifest in some studies in five to ten percent of patients. Also, related to the late toxicity of anthracycline treatment in survivors of childhood cancer. What is particularly interesting about this isoform of phosphoinositide 3-kinase, the gamma isoforms, is that at the same time blocking this enzyme in macrophages increases the anti-tumor, I think it's the anthracycline therapy, and blocking it in the cardiomyocytes, suggests a potential cardioprotective mechanism.
Having a target that can be used both to enhance the anti-cancer effect of anthracycline and to enhance the cardioprotective mechanism is really a potential ideal intervention that would help maximize the anti-cancer treatment and at the same time protect the heart.
Dr Greg Hundley: Fantastic. Again, new research helping to come up with ways for those that continue to need anthracycline therapy that we may be able to attenuate some of the untoward cardiovascular effects, all the while preserving the antagonistic features associated with the treatment for cancer.
Let's switch to the other sort of prospective original research format that we have in Circulation, and that's our letter format. Remember, our letters are addressing a specific point that can be readily appreciated in 800 words or less. The first is a letter by Anquetil et al that examines individuals recorded in the VigiBase World Health Organization database. This is basically a database organized around treatment of cancer and cancer therapeutics and it is examining those individuals that received sort of a newer class of agents called immune checkpoint inhibitors. Remember, that is modulation of our immune system to help attack cancer.
In some rare circumstances, relatively infrequent, when these agents have been administered, the immune system has been unlocked and attacks the heart, promoting a myocarditis that if not recognized can be fulminant and lead to death. This particular group identified a new phenomenon that we need to be aware of and that's just frank myositis.
Vlad, what are your thoughts on now perhaps these agents being associated with the development of myositis in the skeletal muscle?
Dr Vlad Zaha: Often when adverse events, as you mentioned Greg, are an important concern for these new powerful tools for the oncologists and it has been pretty early in the process where some of the cases have demonstrated severe cardiovascular events. Fortunately it is a very low percentage, less than 1% of cases that can manifest with fulminant myocarditis, but this raises again a question of expanding the view towards other systems when we are applying one of these early novel molecular interventions.
In this context, the recognition of myositis in another small percentage of patients is an important observation and increasing awareness of both cardiologists and oncologists towards this side effect is important as not all fatigue is equal and sometimes that can be due to manifestations of cardiomyopathy and sometimes it can be a manifestation of oxygen extraction in the peripheral tissue than muscle contractility. It is an important hypothesis-generating piece that will allow people to appreciate more of the complexity of addressing the intrinsic molecular mechanisms in cancer and heart disease.
Dr Greg Hundley: It sounds that we need to be aware of another potential etiology of fatigue to put in an armamentarium of differential diagnoses for those patients that are not getting quite back to where they were from an exercise and activity level after treatment. The second research letter focuses on individuals that are receiving a Fontan procedure. Remember, Fontan procedures are surgical corrections for those primarily with single ventricles where we're diverting caval blood to the pulmonary circulation, since in some situations there's really no functional right ventricle. These patients over time experience chronic venous hypertension and have associations with liver disease.
In this particular research letter, the authors are examining the relationship between really for the first report in an aggregate form of the relationship between undergoing a Fontan procedure and the development of hepatocellular carcinoma. Vlad, any quick comments to highlight on this particular procedure? I thought something that was interesting is that these individuals experienced these hepatocellular carcinomas in their 20s and 30s.
Dr Vlad Zaha: That's right, Greg. This study confirms observations from previous case reports and the early occurrence of hepatocellular carcinoma is raising still important hypotheses for future clinical trials. On one hand, either there is an increased risk of hepatocellular carcinoma development in patients with non-cirrhotic livers after a Fontan operation, or the current screening modalities using imaging are insufficiently sensitive to identify early signs of cirrhosis in such patients and this stratifies them effectively at an early stage in their disease post-op Fontan procedure.
Dr Greg Hundley: Lastly, let's just briefly discuss here, Vlad, some of the other editorials and review article formats that we have in Circulation. A particular one, a perspective that was written by Peter Libby and Ebert and associates that highlights this phenomenon potentially implicating inflammation and the link between cancer and atherosclerotic cardiovascular disease. The topic of this perspective is really on something called CHIP, which stands for clonal hematopoiesis of indeterminate potential.
What is this CHIP? As we age, basically what happens is we accumulate mutations of hematopoiesis stem cells in our bone marrow. Over time these little clones, they actually have within our bone marrow some survival advantages and they can spill out into the blood and actually can be associated with future leukemias. Those that have a large population of this particular clonal progeny, these CHIP-type cells, they have an increased risk of developing cancer, but also the levels of these are associated with increased overall mortality and it appears some risk of cardiovascular disease. How could that be? One characteristic of this particular cell line is they are associated with dysregulation of inflammatory genes that go on to produce, are associated with other inflammatory mediators.
Vlad, this is calling in question and helping us to examine the relationship between inflammation, cancer and cardiovascular disease. What are your thoughts here about these very important insights provided by Libby and Ebert?
Dr Vlad Zaha: This is a fascinating perspective, Greg. It really brings, again, in the offline novel molecular mechanisms that have been discovered recently and that are becoming a turning point into the molecular interventions, not only in cancer but potentially soon in cardiovascular disease prevention and treatment. Having a common root for a problem set involving such a prevalent cardiovascular problem as atherosclerosis and cancers reveals the connection between the different systems and the fact that integrating our understanding of the molecular regulation of cell proliferation results in an effective translation of leading to new targets and new approaches to treat disease.
It is striking that there are multiple areas where cancer and inflammation are interacting, one of them being at the cellular level and other ones at humoral levels, in a way reproducing other complex mechanisms that we see in regulation of inter-system interactions within the body.
Dr Greg Hundley: And so, summarizing this entire issue in Circulation, what a wonderful collection of a series of original manuscripts, both in the extended and the letter format as well as review articles, including a primer by Handy and associates that evaluates or draws attention to our screening tools that how we might examine the relationship between cardiology and the whole world or hematologic oncology related issues. And then this very unique perspective by Peter Libby and really is a continuation of the growth of this, as we called earlier, the bridging discipline of cardiovascular medicine and oncology as we work toward improving survivorship of all individuals with cardiovascular disease and cancer.
I want to thank you for the opportunity to be with you today and encourage you to follow these issues further with the journal. I'll turn this over to Vlad for any closing remarks.
Dr Vlad Zaha: Thank you, Greg. This has been a really exciting overview of important points that are emerging now at this nexus between cardiology and oncology that give us a broader view of the complex interactions that the future will materialize for us, emerging from a molecular intervention on cancer, heart disease, immunologic disease and probably metabolic endocrinology disease.
Thank you for listening.
Dr Carolyn Lam: Thank you so much, Vlad and Greg. This is a tremendous issue and I'm sure, audience, you will be reaching for it right now, I would.
Please let all your colleagues know about this podcast and tune in again next week.
Can proteomic biomarkers distinguish between subtypes of aortic stenosis even years before surgery? Well, to find out more, stay tuned. That's coming right up after these summaries.
The first original paper this week adds to the evidence that smoke-free policies are associated with a lower risk of cardiovascular disease. First and corresponding author, Dr Mayne from Northwestern University Feinberg School of Medicine, and her colleagues linked smoke-free policies to participants of the Coronary Artery Risk Development in Young Adults, or CARDIA study, which has a follow-up of up to 20 years. They found that smoke-free policies in workplaces were associated with significantly lower risk of incident cardiovascular disease after controlling for a wide range of covariants. Results were weaker for bar and restaurant bans, but in the same direction.
Preventive fractions range from an impressive 24 to 46%. Thus, smoke-free policies may improve cardiovascular health through reducing population exposure to tobacco smoke. However, we should remember that much of the US population remains unprotected by smoke-free policies. Thus, taken together with prior ecological work, these results support the continued expansion of smoke-free policies in indoor public places.
Most phase-3 randomized control trials feature time-to-first event end points for their primary analysis. In chronic diseases, however, a clinical event can occur more than once and recurrent event methods have been proposed to more fully capture the disease burden, as well as to improve statistical precision and power.
However, is this really the case? This question was examined by first author, Dr Brian Claggett, corresponding author, Dr Scott Solomon, from Brigham Women's Hospital in Boston, Massachusetts, and their colleagues, who sought to better characterize factors that influence the statistical properties of recurrent events and time-to-first event methods in the evaluation of randomized therapy.
They performed repeated simulated trials with 1:1 randomization of 4000 patients to active versus control therapy. Through simulation, they varied the degree of between-patient heterogeneity of risk as well as the extent of treatment discontinuation. They then compared their findings with those from the actual randomized control trials.
The authors found that the statistical power of both recurrent events and time-t- first event methods were reduced by increasing heterogeneity of patient risk, a parameter that's not usually included in conventional power and sample size formulae. Furthermore, data from real clinical trials were consistent with the simulation studies, confirming that the greatest statistical gains from the use of recurrent events methods occurred in the presence of high patient heterogeneity and low rates of study drug discontinuation.
The next paper uncovers a novel biomarker and therapeutic target of pulmonary arterial hypertension, and that is selenoprotein P. First author Dr Kikuchi, corresponding author, Dr Shimokawa, from Takaoka University Graduate School of Medicine in Japan and their colleagues performed micro-array analyses using pulmonary arterial hypertension, pulmonary artery smooth muscle cells, and found a 32-fold up regulation of selenoprotein P compared with controls.
Selenoprotein P promotes cell proliferation and apoptosis through increased oxidative stress and mitochondrial dysfunction. Using five strains of genetically modified mice, the authors demonstrated a pathogenic role of selenoprotein P in the development of hypoxia-induced pulmonary hypertension.
Furthermore, sanguinarine, which is an orally active small molecule identified by throughput screening reduced selenoprotein P expression and pulmonary arterial smooth muscle cell proliferation and ameliorated pulmonary hypertension.
In summary, this study shows that selenoprotein P plays a crucial role in the pathogenesis of pulmonary arterial hypertension and may be a useful and novel biomarker and therapeutic target in this disorder.
Familial hypercholesterolemia is known to be associated with a high risk of ischemic heart disease, including myocardial infraction, but what about the risk of ischemic stroke? Well, first author, Dr Beheshti, corresponding author, Dr Nordestgaard, from Copenhagen University Hospital and their colleagues examined the associations of familial hypercholesterolemia and high LDL cholesterol with ischemic stroke in both causal, genetic, and observational analyses using more than 106000 individuals from the Copenhagen General Population Study, and more than 10000 individuals from the Copenhagen City Heart Study.
They used a Mendelian randomization design to test whether high LDL per se had a causal effect on ischemic stroke risk using a combination of the familial hypercholesterolemia causative mutations and common genetic variants associated with high LDL.
The authors found that there was no association between familial hypercholesterolemia mutations and ischemic stroke risk. In the Mendelian randomization analysis, also including common genetic variants, there was also no causal effect of high LDL on the risk of ischemic stroke.
These findings imply that the predominant goal of targeting LDL lowering in those with and without familiar hypercholesterolemia is likely to reduce myocardial infractions, rather than ischemic stroke. Well, that wraps it up for our summaries. Now for our feature discussion.
Circulation publishes numerous papers regarding circulating biomarkers. We talk about biomarkers in the diagnostic, prognostic sense, but what about in a pathophysiologic sense, and especially in a disease as important as aortic stenosis? Well, that's what our featured paper this week is all about and I'm so excited to have with us corresponding author, Dr Stefan Söderberg, from Umeå University in Sweden, as well as our associate editor, Dr Peipei Ping from UCLA. We will be discussing the paper entitled “Proteomic Biomarkers for Incident Aortic Stenosis Requiring Valvular Replacement.” Stefan, could you tell us a bit about what made you look at this very interesting question, and perhaps the unique resources you had in Sweden to look at this?
Dr Stefan Söderberg: I'm a practicing cardiologist, and I have been working a lot with aortic stenosis over the years. It's frustrating that we can't do anything to stop the process. In many cases, the patients are old and frail, and if you could find the means to stop the process long before they need surgery, it will be of great benefit for the human and for the society.
Also, knowing that the interventions on the statins, for example, have been unsuccessful, we thought that there must be better ways or other biomarkers. Furthermore, that many of these studies, the phenotype of aortic stenosis has been very poorly described and there is probably much more behind just aortic stenosis than just, for example, calcium deposits in an X-ray, et cetera, et cetera.
Dr Carolyn Lam: You used some very unique resources in Sweden to therefore look at the proteomic signatures of aortic stenosis. Could you describe that and simplify perhaps the results so we can understand it?
Dr Stefan Söderberg: First of all, I got this idea from other studies done up in northern Sweden. If you have an absolutely unique setting, the combination of huge population-based studies in 30 years back, we have a huge biobank with examples of extraordinary good quality from each of these participants. For example, for each participant, the blood has been spun and put into freezer, deep freezer, within one hour for 30 years, and they are now, as I said, about 100000.
Furthermore, I'm working as a cardiologist at a university, and up here, you do all of the aortic surgery for the whole northern Sweden. That is, we can combine the names of the person undergoing surgery together with these population-based surveys and we can get details from all those who have participated in the surveys long before they did the surgery, and they can go and retrieve samples from cases and match controls from the freezers. It's a unique setup. Then, when we were designing the study, we got the chance to get these analyses done by our friends at the university to get the proteomic analysis via a unique data technique.
Dr Carolyn Lam: Wow. Could you describe your results?
Dr Stefan Söderberg: The results that we found in the first set of 334 patients who underwent surgery is 10 years after their first sampling, we found six proteins. Then, we got the question back from Circulation to establish a validation cohort, and we were able to do so to include all those new cases in the last 2 years, and there we could replicate five of these proteins.
The interesting thing that the pattern is completely different between those having coronary artery disease from those without. That kind of phenotyping has not been done throughout other aortic stenosis studies. Therefore, this study is unique. We have had two papers in the last year in the Journal of American Heart Association from the cohort, as well, showing the thing that happened.
For example, lipoprotein little A is only associated with future aortic stenosis valve replacement only in those with concomitant coronary artery disease. There are many unique things, the prospective design, and the phenotype differentiating those with and without coronary artery disease.
Dr Carolyn Lam: Yeah, and if I may just reiterate that the population base that you work with is just enviable and just so that the audience realizes, these are biomarkers that were collected 11 years before the aortic stenosis surgery, isn't it? You really had a long follow-up.
Also, just to let everyone know, it was a proximity extension assay that you used for the discovery, and the six proteins were growth differentiating factor 15, or GDF15, galectin-4, von Willebrand factor, interleukin 17 receptor A, transferrin receptor protein 1, and PCSK9, so very interesting. Peipei, you have a way of putting things into context so beautifully. Could you tell us your thoughts when you saw this paper?
Dr Peipei Ping: I thought this is a very high-quality study that actually benefited from the long-term established, well-controlled cohort in northern Sweden, as Dr Söderberg just shared with us. On the other end, it married a technology platform that's very well-established and -validated, and this situation targeted proteomics platforms using multi-proximity extension assays with carefully controlled markers and screened 92 cardiovascular candidate markers.
This is the kind of approach that provides semi-quantitative as well as quantitative outputs and is capable to offer validated screens on large population clinical subsets. A study of such with a high value cohort combined with a validated and well-controlled technology platform offered results that clearly have clinical significance, as well as setting up examples for other studies to follow. The enthusiasm from the editorial boards, as well as the reviewers, have been substantially high and supportive.
Dr Stefan Söderberg: Fantastic. I'm very glad to hear this.
Dr Carolyn Lam: Stefan, you also mentioned that a very unique element was the separation of aortic stenosis with and within coronary artery disease, or at least established or visible coronary artery disease. Could you explain how that provided pathophysiologic insights?
Dr Stefan Söderberg: First, I should say we were very, very strict. Our routine is that everyone was 100% undergoing, aortic valve replacement, they undergo a coronary angiogram before. If we saw any sign of atheromatosis, it was not enough that they had the significant stenosis, but any signs, they were put into the group of coronary artery disease. Those without, we couldn't see anything there. Radiograph here reported absolutely clean coronary arteries. Of course, we cannot exclude if there were aortic changes within them all, of course.
We believe that this is a very important message that in order to further study aortic stenosis, we should be very careful in phenotyping the disease. We hope the growing cohort will be able to do this further. For example, cuspid versus tricuspid valves, women versus men, et cetera.
My answer in short is phenotype. Let me take one example which I found very, very exciting. That is the finding of PCSK9, which is closely related not only to cholesterol symptoms, but also to lipoprotein little A emphasis. As you know, the first strong finding in aortic stenosis was the LP little A. This is related to that genetic finding, and that was in the huge study from Canada. They did not have the same phenotyping, so we had information to his important findings. That's one example.
Another example is the transferring receptor, where data has shown that bleeding acutely in the valvular tissue causes damage, and this relates iron metabolism to the formation of the aortic valve. Obviously, it seems that the process in the aortic valve is very much similar to the vessel arteriosclerosis. It seems to be different. This is the indication that when we formulate new studies or new drugs on aortic stenosis, we must be very careful to use the right drug for the right type of valvular disease.
Dr Carolyn Lam: Those are great points. Peipei, do you think that's the main clinical take-home message, beyond that great comment you made earlier that this paper's just a great example of the use of tools, modern tools, that we have in proteomic characterization like the proximity extension assay to provide pathophysiologic insights when you have a really well-phenotyped cohort? What's the critical take-home message, though? Is there one now?
Dr Peipei Ping: The take-home message is marriage of amazing high value cohort's data sets with that of the well-controlled clinical study using target proteomics approaches. In this particular study, one main critical innovation is the study is capable of providing insights regarding molecular signatures that have predicted values. As stated in the manuscript, the circulating proteins that found critically important, their alterations took place years before the surgery were associated with aortic stenosis. That is of value, clinical value, to many other clinical studies to follow.
Dr Carolyn Lam: Wow. That's wonderful. Thank you so much for putting these findings in context for us. Thank you, listeners, for joining us today. Don't forget to tune in again next week.
Does measuring baseline BNP add prognostic information in patients undergoing revascularization for left main coronary artery disease? Well, to find out the answers, you have to stay tuned and listen up for our feature discussion coming right up, after these summaries.
The first original paper this week reports a new role for bone morphogenetic protein 9, or BMP9, as an endogenous inhibitor of cardiac fibrosis. Now, we are familiar with transforming growth factor beta-one, or TGF-β1, as a promoter of cardiac fibrosis. TGF-β1 also activates counterregulatory pathways that serve to regulate TGF-β1 activity in heart failure. BMP9 is a member of the TGFβ family of cytokines and signals via the downstream effector protein Smad1.
In the current paper from first author Dr Morine, corresponding author Dr Kapur, from Tufts Medical Center in Boston, and their colleagues. The authors examined BMP9 expression and signaling in human cardiac fibroblasts and human subjects with heart failure. They utilized the thoracic aortic constriction–induced model of heart failure to evaluate the functional effect of BMP9 signaling on cardiac remodeling. The authors’ results identified a novel functional role for BMP9 as an endogenous inhibitor of cardiac fibrosis due to LV pressure overload. They further showed that treatment with either recombinant BMP9 or inhibiting a high affinity receptor for BMP9 known as endoglin promoted BMP9 activity and limited cardiac fibrosis in heart failure. Thus, this provides a potential novel therapeutic approach for patients with heart failure.
The next paper shows that endothelial C-type natriuretic peptide, or CNP, regulates microcirculatory flow and blood pressure. First author, Dr Špiranec, corresponding author Dr Kuhn, and colleagues from University of Würzburg in Germany analyzed whether vasodilating response to CNP changed along the vascular tree. In other words, whether the guanylyl cyclase–B receptor was expressed in microvascular types of cells. The authors used novel gene-modified mouse models to show that guanylyl cyclase–B cyclic GNP signaling in parasites diminished microcirculatory resistance and arterial blood pressure. In contrast, endothelial, or macrovascular smooth muscle cell guanylyl cyclase–B signaling was not involved. This indicated that CNP participated in the local cross talk between endothelial cells and parasites, thus playing an important role in the maintenance of normal microvascular resistance and blood pressure. Thus, pharmacological augmentation of endogenous CNP signaling in parasites may provide a useful therapeutic tool to combat increased vascular resistance and hypertension.
Has the rapid and exponential growth in transcatheter aortic valve replacement, or TAVR, demand overwhelmed capacity, thus translating to inadequate access and prolonged wait times? Well, the next paper provides some answers. First author, Dr Elbaz-Greener, corresponding author Dr Wijeysundera, from University of Toronto, evaluated temporal transient TAVR wait times and the associated clinical consequences in their population-based study of all TAVR referrals from April 2010 to March 2016 in Ontario, Canada. Their study cohort included 4,461 referrals, of which 50% led to a TAVR, 39% were off-listed for other reasons, and 11% remained on the wait list at the conclusions of the study.
For patients who underwent a TAVR, the estimated median wait time in the post reimbursement period stabilized at 80 days and has remained unchanged. The cumulative probability at 80 days of wait-list mortality was 2% and of heart failure hospitalization, 12%, with an increase in events with increased wait times. Thus, post reimbursement wait time has remained unchanged for patients undergoing a TAVR procedure, suggesting that the increase in capacity has kept pace with the increase in demand. The current wait time of almost 3 months is associated with important morbidity and mortality, suggesting a need for greater capacity and access.
The final paper shows that patients with type 2 diabetes and a history of heart failure are particularly likely to benefit from treatment with the SGLT2 inhibitor canagliflozin. First author, Dr Rådholm, corresponding author Dr Figtree, from Royal North Shore Hospital in Australia, and colleagues, studied more than 10,000 participants with type 2 diabetes and high cardiovascular risk in the CANVAS Program who were randomly assigned to canagliflozin or placebo and followed for a mean of 188 weeks. Participants with a history of heart failure at baseline constituted 14.4% of the study population and were more frequently women, white, and hypertensive, with a history of prior cardiovascular disease. The benefit of canagliflozin on cardiovascular death and hospitalized heart failure was greater in patients with a prior history of heart failure compared to those without heart failure at baseline with a p for interaction of 0.02. The effects of canagliflozin compared with placebo on other cardiovascular outcomes and key safety outcomes were similar in patients with and without heart failure at baseline. Effects were apparent across a broad range of participant subgroups, including those using established treatments for the prevention of heart failure, such as renin-angiotensin-aldosterone system inhibitors, diuretics, and beta-blockers. Thus, patients with type 2 diabetes and a history of heart failure may be particularly likely to benefit from treatment with canagliflozin. The beneficial effects of canagliflozin on heart failure outcomes unlikely to be accrued on top of other therapies for heart failure management.
And that brings us to the end of this week's summaries, now for our feature discussion.
In patients with left main coronary artery disease who are undergoing revascularization, could BNP assessment be that precision medicine tool to aid us in our clinical decision making? Well, I am just so excited to discuss this very topic with the corresponding author for this feature paper, Dr Gregg Stone from Columbia University Medical Center, as well as our associate editor and editorialist for this paper, Dr Torbjørn Omland from University of Oslo.
Gregg, it was a super smart idea to look at circulating BNP and how this may associate with outcomes, as well as therapies in the EXCEL trial. Please tell us what inspired you to do this and please tell us what you found.
Dr Gregg Stone: As everybody knows, BNP has been identified as an important prognostic factor in patients with heart failure and ischemic heart disease. It correlates with both cardiovascular and noncardiovascular mortality. Patients with left main disease are among the highest-risk patients that either interventional cardiologists or cardiac surgeons treat because of the amount of myocardium at risk, they often present in heart failure, and even if they're not in overt heart failure, they can be prone to large severe left ventricular dysfunction. So first we wanted to establish the prognostic utility of BNP in this patient population and then we were interested to see if it might have a role in helping differentiate which patients might have a better prognosis with either PCI or coronary artery bypass graft surgery.
EXCEL is the largest trial to date of left main PCI versus CABG in a randomized format with 1905 enrolled patients. And overall, we found that PCI and CABG had similar rates of deaths, large myocardial infarction, or stroke in 3 years. But of course, there are high risk-patients and low-risk patients buried within those overall aggregate outcomes, and BNP was an important prognostic predictor of overall mortality in the trial. Both cardiovascular and noncardiovascular, but not of any other ischemic end points interestingly. Not myocardial infarction, stent thrombosis, graft occlusion, bleeding, revascularization. But definitely, mortality. Even independent of left ventricular ejection fraction and heart failure status.
Now, when we looked at the outcomes of PCI versus bypass surgery, we actually found a very powerful interaction, such that at relatively lower BNP levels, patients who underwent PCI had a better prognosis and tended to have lower mortality. Where patients with high baseline BNP levels tended to have a better prognosis after surgery.
Dr Carolyn Lam: You know, Torbjørn, I love your editorial where you contextualize these findings so nicely. Could you do that for us now?
Dr Torbjørn Omland: First, I would like to congratulate Gregg and his team with this very interesting and very well-done study, and I think Circulation is very fortunate to be able to publish papers like this. We have known for quite a long time that BNP is a strong prognostic indicator across the spectrum of cardiovascular diseases and it seems to be particularly strongly associated with risk of heart failure events, cardiac arrhythmias, and risk of death. And, as shown in the EXCEL trial, the association with left ventricular ejection fraction is actually quite weak, and also the association with ischemic events. So, these findings fit very well with previous observations. The really novel and intriguing finding of this study is the very strong interaction between procedural BNP levels and the effect of the randomized therapies and, as you alluded to, all the investigators have tried to look at this in other more low-risk populations like in the LIPID trial but actually failed to find any significant interaction. It's really a novel and important finding.
Dr Carolyn Lam: That's true. Does it bring up the question are the natriuretic peptides just a better EF measurement? You mentioned that there was a correlation, what do you think, Gregg?
Dr Torbjørn Stone: Well, you know, there was a weak correlation between BNP and ejection fraction and history of heart failure but the prognostic utility of BNP in this study and its ability to differentiate between the outcomes of PCI versus CABG in patients with low versus high BNP was actually strongly independent of both congestive heart failure history and acute left ventricular ejection fraction. So, I think the BNP is giving a useful independent information. It's a strong reflector of both atrial and ventricular pressures and volume status, but it also reflects myocardial hypoxia, it may be involved in glycolysis and lipid peroxidation, and other mechanisms that we don't fully understand. There may be elements of diastolic dysfunction that we have not measured in this study and other mechanisms related to prognosis in these patients. So, while EXCEL was not set up to truly differentiate and delve deeply into the mechanisms of our observations, statistically these were strong associations that may prove clinically useful.
Dr Carolyn Lam: Right, I thought that was so intriguing as well, just the points that you brought up. First, let's just clarify for the audience that when you say low and high you were using a cutoff of 100.
Dr Gregg Stone: We did use a cutoff of 100 pg per mL as is common, but we also modeled BNP as a continuous measure. And actually the relationships were even stronger when modeled as a log hazard ratio continuous measure, both for mortality and for the primary end point.
Dr Carolyn Lam: Yeah, that's so cool. And Torbjørn, you talked about this in your editorial as well and I thought your point about the distributions of the ejection fraction versus the distribution of natriuretic peptide, that was very revealing, too. Would you like to explain your thoughts there?
Dr Torbjørn Omland: I found it very interesting that all of this is clearly a high-risk operation overall. More than 90% actually had what we regard a normal, or at least not a reduced ejection fraction. Whereas the distribution of BNP values were more widely distributed so that actually about 40% of participants had BNP levels above this ratio of 100 pg per mL. And that probably shows that in this population, BNP provides additional and independent information about the status of the myocardium that is not revealed by angiography or ejection fraction measurements.
Dr Carolyn Lam: That's true, and that's an important point because it added above the SYNTAX score, too, right Gregg?
Dr Gregg Stone: That's right, it was an independent predictor, and in fact the SYNTAX score and the severity of left main coronary disease did not vary, according to BNP levels, that is. High versus low BNP were equally distributed, not related to the anatomic extent and complexity of coronary artery disease. So, BNP is clearly reflecting a different state of the myocardium in a way that we can't measure with any other available test and that makes it quite a useful biomarker.
Dr Carolyn Lam: Exactly, so I think I'd like to wrap up with asking you both, you can already see what the potential clinical implications are, right? Which means that perhaps in a similar type of patient where there's equipoise of the revascularization method and has left main disease, maybe we should be using natriuretic peptides to guide our clinical decision making. What do you think are next steps before this is prime time?
Dr Gregg Stone: Well I can mention that when one makes a decision of the best revascularization modality for patients with extensive multi-vessel or left main coronary artery disease, there are many factors that go into that determination, both clinical, anatomic, is the patient a good candidate for one versus the other revascularization modality, what are the patient's preferences, what's the surgeon's or interventionalist's likelihood of being able to safely get the patient through the procedure and achieve complete revascularization.
The SYNTAX score makes a difference, as does gender and age and kidney disease and COPD and ejection fraction and many other factors. So I think we can now add to that list BNP, although I will say this was a post-hoc study, we only had BNP available in approximately 60% of the patients, and while the outcomes were similar in the patients who we did not versus who we did have BNP, this has to be looked at as hypothesis-generating analysis, and we would love to also see this type of finding replicated in other large datasets. That being said, there are no other large left main or new multi-vessel disease trials that are planned right now to my knowledge, and I think given the breadth of this dataset and its size and scope, I do think that these findings are robust enough to use BNP as one of the clinical factors to consider in revascularization decisions.
Dr Torbjørn Omland: I actually agree with that and I think ideally, we would, of course, like to see external validation in another dataset and even retrospective randomized study comparing conventional versus BNP-guided strategy but that may not be realistically undertaken. So, I think these are clearly the best data we have and as clinicians need to integrate this in our overall evaluation in making this important decision.
Dr Carolyn Lam: Yeah, I mean Gregg, could I ask you, do you apply this clinically already?
Dr Gregg Stone: We have not been before this, although I believe we will now. I believe BNP should be a biomarker that we more routinely measure in patients with ischemic heart disease as well as those with overt congestive heart failure. And again, use as one of the factors of many when making revascularization decisions. And I think it's important to note also that the PCI patients tended to preferentially benefit, in fact with even lower mortality when BNP was lower. Where the surgical patients tended to benefit when BNP was higher. So, it's one factor, not the only factor, but I think it's one additional piece of the puzzle.
Dr Carolyn Lam: Yeah, I have to say too I mean, after reading this, after reading this awesome editorial, it's hard not to think I should be applying this clinically because it's going to be really hard and take a long time to prove this with more prospective data, for example. Although, external validation and other datasets may be better, this is the largest trial already to show this and show it so clearly with a significant interaction. I think that is striking to me.
Torbjørn maybe I've put you on the spot with the last word, does this change your clinical practice?
Dr Torbjørn Omland: I agree with Gregg. This will be one of maybe several other factors but I think it's ready for being taken into account when making this sometimes very difficult decision.
Dr Carolyn Lam: Thank you so much Gregg and Torbjørn for joining me today. You've been listening to Circulation on the Run. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. Did you know that despite being one of the wealthiest nations in the world, the United States population has a shorter life expectancy compared to almost all other high-income countries in the world? Well, stay tuned to learn what Americans could do to narrow the life expectancy gap between the United States and other industrialized nations. Coming right up after these summaries.
Are microRNAs involved in nitrate tolerance? Well, the first original paper this week provides some answers. This is from co-corresponding authors Dr Bai and Zhang from Central South University in Changsha, China. Nitrate tolerance develops when there's dysfunction of the prostaglandin I2 synthase and prostaglandin I2 deficiency. These authors hypothesize that prostaglandin I2 synthase gene expression may be regulated by a microRNA-dependent mechanism in endothelial cells. They induce nitrovasodilator resistance by nitroglycerin infusion in Apoe deficient mice and studied endothelial function in both the mouse models as well as human umbilical vein endothelial cells. They found that nitric oxide donors induced atopic expression of microRNA 199a/b in endothelial cells, which was required for the nitrovasodilator resistance via repression of prostaglandin I2 synthase gene expression. Targeting this axis effectively improved nitrate tolerance. Thus, the atopic expression of microRNA 199 in endothelial cells induced by nitric oxide may explain prostaglandin I2 synthase deficiency in the progression of nitric tolerance. Thus, microRNA 199a/b may be a novel target for the treatment of nitric tolerance.
What are the long-term outcomes of childhood left ventricular noncompaction cardiomyopathy? Well, the next paper presents results from the National Population-Based Study in Australia. First author, Dr Shi, corresponding author, Dr Weintraub, from Royal Children's Hospital in Melbourne, looked at the National Australian Childhood Cardiomyopathy Study, which includes all children in Australia with primary cardiomyopathy diagnosed at less than 10 years of age between 1987 and 1996. Outcomes for left ventricular noncompaction patients with a dilated phenotype will compare to those with a dilated cardiomyopathy.
There were 29 patients with left ventricular noncompaction with a mean annual incidence of newly diagnosed cases of 0.11 per hundredth thousand at risks persons.
Congestive heart failure was initial symptom in 83%, and 93% had a dilated phenotype. The median age at diagnosis was 0.3 years of age. Freedom from death or transplantation was 48% at 10 years after diagnosis, and 45% at 15 years. Using propensity score inverse probability of treatment-weighted Cox regression, the authors found evidence that left ventricular noncompaction with a dilated phenotype was associated with a more than two-fold greater risk of death or transplantation.
The next paper reports the first application of multiomics and network medicine to calcific aortic valve disease. Co-first authors Dr Schlotter and Halu, corresponding author Dr Aikawa from Brigham and Woman's Hospital and Harvard Medical School in Boston, and their colleagues examined 25 human stenotic aortic valves obtained from valve replacement surgeries. They used multiple modalities, including transcriptomics and global unlabeled and label-based tandem-mass-tagged proteomics.
Segmentation of valves into disease stage–specific samples was guided by near-infrared molecular imaging. Anatomic-layer specificity was facilitated by laser capture microdissection. Side-specific cell cultures was subjected to multiple calcifying stimuli, and the calcification potential and basil or stimulated proteomics were evaluated. Furthermore, molecular interaction networks were built, and their central proteins and disease associations were identified.
The authors found that global transcriptional and protein expression signatures differed between the nondiseased, fibrotic, and calcific stages of calcific aortic valve disease. Anatomical aortic valve microlayers exhibited unique proteome profiles that were maintained throughout disease progression and identified glial fibrillary acidic protein as a specific marker of valvula interstitial cells from the spongiosa layer. In vitro, fibrosa-derived valvular interstitial cells demonstrated greater calcification potential than those from the ventricularis. Analysis of protein-protein interaction networks further found a significant closeness to multiple inflammatory and fibrotic diseases. This study is significant because it is the first application of spatially and temporarily resolved multiomics and network systems biology strategy to identify molecular regulatory networks in calcific aortic valve disease. It provides network medicine–based rational for putative utility of antifibrotic and anti-inflammatory therapies in the treatment of calcific aortic valve disease. It also sets a roadmap for the multiomic study of complex cardiovascular diseases.
The final paper tackles the controversy of antibiotic prophylaxis for the prevention of infective endocarditis during invasive dental procedures. This is from a population-based study in Taiwan. First author, Dr Chen, corresponding author, Dr Tu from Institute of Epidemiology and Preventive Medicine College of Public Health in National Taiwan University aimed to estimate the association between invasive dental treatments and infective endocarditis using the health insurance database in Taiwan.
They chose 2 case-only study designs. First a case-crossover, and second, self-controlled case series. Both designs used within-subject comparisons such that confounding factors were implicitly adjusted for. They found that invasive dental treatments did not appear to be associated with a larger risk of infective endocarditis in the short period following invasive dental treatment. Results were consistent from both study designs. The authors also did not find any association between invasive dental treatments and infective endocarditis even among the high-risk patients, such as those with a history of rheumatic disease or valve replacement.
In summary, these authors found no evidence to support antibiotic prophylaxis for the prevention of infective endocarditis before invasive dental treatments in the Taiwanese population. Whether antibiotic prophylaxis is necessary in other populations requires further study.
Alright, so that wraps it up for our summaries, now for our feature discussion.
The United States is one of the wealthiest nations worldwide, but Americans have a shorter life expectancy compared with almost all other high-income countries. In fact, the US ranks only 31st in the world for life expectancy at birth in 2015. What are the factors that contribute to premature mortality and life expectancy in the US? Well, today's feature paper gives us some answers. And I'm just delighted to have with us the corresponding author, Dr Frank Hu from Harvard T.H. Chan School of Public Health, as well as our dear associate editor, Dr Jarett Berry, from UT Southwestern.
Frank, could you begin by telling us a bit more about the inspiration for looking at this, what you did, and what you found?
Dr Frank Hu: So, we look at the impact of healthy lifestyle habits, life expectancy in the US as a nation. As you just mentioned, Americans have a shorter life expectancy compared with almost all other high-income countries, so in this study we wanted to estimate what kind of impact of lifestyle factors have, premeasured that and life expectancy in the US population.
What we did is to combine three datasets. One is our large cohort, Nurses’ Health Study, and Health Professionals Follow-Up Study. We use this large cohort to estimate the relationships between lifestyle habits and mortality. And the second data set we use is to get age and sex to specific mortality rates in the US as a nation. This is the CDC WONDER dataset. And the third dataset we used is the NHANES dataset, this is the National Health and Nutrition Examination Survey. We used this dataset to get the prevalence of healthy lifestyle factors in the general US as a nation. So, we used the three datasets to create age-specific, sex-specific life tables and estimated life expectancies.
At age 50, according to the number of healthy lifestyle habits that people would follow, what we found is that following several lifestyle factors can make a huge difference in life expectancies.
Here we talk about five basic lifestyle factors: not smoking, maintaining a healthy weight, exercise regularly—at least a half hour per day—and eating a healthy diet, and not drinking too much alcohol. No more than one drink per day for a woman, no more than two drinks per day for men. What we found is that, compared with people who did not adapt any of those low-risk habits, we estimated that the life expectancy at age 50 was 29 years for woman and about 26 years for men. But for people who adapted all five healthy lifestyle habits, life expectancy at age 50 was 43 years for women and 38 years for men. So, in other words, a woman who maintains all 5 healthy habits gained, on average, 14 years of life, and the men who did so gained 12 years life compared with those who didn't maintain healthy lifestyle habits. So I think this is a very important public health message. It means that following several bases of healthy factors can add substantial amount of life expectancy to the US population, and this could help to reduce the gap in life expectancy between the US population and other developed countries.
Dr Carolyn Lam: Thank you, Frank. You know that is such an important public health message that I am going to repeat it. Adhering to five lifestyle risk factors mainly, don't smoke, maintain a healthy weight, have regular physical activity, maintain a healthy diet, and have moderate alcohol consumption, AND a woman could increase her life expectancy at age 50 by 14 years and a man could do that by 12 years more. That is absolutely amazing.
Okay so Frank, actually, I do have a question though. These are remarkable datasets obviously, but they also go back to the 1980s. So did you see any chief risk factor that may have played more predominant apart with time?
Dr Frank Hu: We didn't specifically look at the changes in risk factors life expectancy, but among the five risk factors, not smoking is certainly the most important factor in terms of improving life expectancy. The good news is that prevalent smoking in the US has decreased substantially in the past several decades. However, the prevalence of other risk factors has actually increased. For example, the prevalence of obesity has increased two- or three-fold and the prevalence of regular exercise remained at a very low level, and also the diet quality in the US population is relatively poor. So, the combination of those risk factors have contributed to relatively low life expectancies in the US population.
Dr Carolyn Lam: Right. Obesity, not smoking, I hear you. I just wanted to point out to all the listeners too, you have to take a look at Figure 1 of this beautiful paper, it’s just so beautifully illustrated in it.
Jarett, you helped to manage and bring this paper through. What are your thoughts?
Dr Jarett Berry: Yeah, I just want to echo your comments, Carolyn, and Dr Hu. This is a fabulous paper, and a very important contribution characterizing these important associations in the US population. And I think, and the discussion thus far has been really helpful in putting all of this into context.
I do want to ask you, just a couple of, I guess more, philosophical questions about some of the observations in the paper. And one of them is the prevalence of the low-risk factor, those with a large number of low-risk factors, for example, in both the Nurses Health and in the Health Professional Follow-Up Study, you observed that the presence of five lifestyle factors was less than 2%. And it's interesting you see this in a large number of datasets and I think important, maybe for our readers to realize that there's two sides to the coin here.
One, the benefit of these low risk factors, but also, unfortunately, the low prevalence of these collections of healthy lifestyle factors that you've outlined.
Could you comment a little bit on that, and what that means, both maybe from a scientific point of view of perhaps, more importantly, from a public health stand point?
Dr Frank Hu: Yeah and this is very important observation and the number of people or the percentage of people who maintained all the five low-risk lifestyle habits is quite low in our cohort, even the nurses and health professionals, they are more health conscience in the general population. They have much better access to health care and also better access to healthy foods and have physical activity facilities. Despite all this potential advantages, and these more percentage of people who are able to maintain all five lifestyle risk factors.
On the other hand, about 10 to 15% of our participants did not adopt any of the five low-risk lifestyle habits. So it means that we still have a lot of work to do in terms of improving the lifestyle habits that we discussed earlier. The five risk lifestyle factors and in the general population, I think the percentage of people who adapt all the five lifestyle factors, probably even lower than 2%. And so that means that we have a huge public health challenge in front of us and have to improving the five lifestyle risk factors. One of the most important public health challenges as mentioned earlier is obesity because currently we have two-third of the US population is overweight or obese. So that's something I think is major public health challenges for us.
Dr Jarett Berry: Right, and it’s interesting looking at your Table 1, and those individuals who have all five low risk factors. It's interesting that the prevalence of physical activity was incredibly high. I have a great interest of impact of exercise on these types of outcomes and it's interesting that in both cohorts, six or seven hours a week of exercise was the mean physical activity level in those with five risk factors. So, it's interesting and in some ways, these lifestyle factors, they do tend to congregate or covary with one another such that those individuals who do spend that kind of time, albeit unfortunately more rare than we would like to see it, the increase in physical activity does tend to have a positive impact, not only on the weight, but also on healthy lifestyle or healthy diet choices.
Dr Frank Hu: Right, yeah this is a very good observation that what I do want to point out that our definition of regular exercise is pretty cerebral to put it in terms of the definition. So we define moderate to vigorous physical activity in our cohorts. We included not just running, playing sports, but it was also walking in a moderate intensity. So it means that people can incorporate physical activity into their daily life. For example, by walking from a train station and with climbing stairs in their workplace and so on and so forth. So here physical activity means both recreational activity and also moderate intensity activities such as graceful walking.
Dr Carolyn Lam: Frank, I think both of us listening are breathing a sigh of relief there and just for the listeners to understand too. These factors were dichotomized, right, and so you were describing the type of exercise and actually you used a three and a half hour per week limit to define healthy or not.
Similarly, just for reference the alcohol intake was 5 to 15g a day for women, or 5 to 30g a day for men. And normal weight was defined as a BMI of 18.5 to 24.9. I'm just thinking that if I were listening I'd want to know those cutoffs.
Now, can I ask a follow-up question, therefore to this dichotomy. As far as I understand you counted each of these risk factors equally, but did you try to do a weighted analysis by any chance? Did any one of them play a bigger role than others?
Dr Frank Hu: That's an interesting mathematical question because it’s very difficult to assign different weights to different risk factors because we look at, not just total mortality but also cardiovascular mortality and cancer mortality. So, you would have to use different weights for different causes of mortality. That would make the analysis much more complicated. But we did calculate a different type of score using five categories of each risk factor and then using that score, we were able to rank people in more categories so for that score the range is from five to 25, and we categorized people into quintiles or even more categories and the contrast in life expectancy between the lowest and the highest group is even greater. So, it means that, the higher number of healthy lifestyle factors, the greater life expectancy. Also, with each category, each lifestyle factors a high degree of adherence to that factor, the greater health benefit people will get. So, I think it's really accumulative fact of multiple risk factors and also the degree of adherence to each of the factors.
Dr Carolyn Lam: Again, such an important public health message.
Jarett, how do you think this is going to be received by the public at large?
Dr Jarett Berry: Very well received. I mean this is a very important observation demonstrating some of these disconcerting observations about life expectancy in the United States and as we think about strategies for improving the public health, I think Dr Hu's group has really helped us outline, very clearly, what other bodies such as the American Heart Association have been saying for years now, that lifestyle factors are so important in influencing cardiovascular risk, and in this case, life expectancy. It really does put, once again, the right amount of emphasis on the role these lifestyle factors of improving the public health. I think it’s going to be very well received and really helpful and important observation that all of us need to hear.
Dr Carolyn Lam: Listeners, don't forget this important message and tell your friends about it, please.
Thanks for joining us today, don't forget to join us again next week.
Dr Carolyn Lam: Welcome to Circulation On the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
In this day and age of endovascular treatment for acute ischemic stroke, does time to treatment really matter? Well, we will be discussing results of the MR CLEAN Registry from real-world clinical practice, coming right up after these summaries.
The first original paper this week describes the first mouse model of progerin-induced atherosclerosis acceleration. Progerin is an aberrant protein that accumulates with age, causes a rare genetic disease known as Hutchinson-Gilford Progeria Syndrome. Patients with Progeria Syndrome have ubiquitous progerin expression and exhibit accelerated aging and atherosclerosis, dying in their early teens mainly from myocardial infarction or stroke. The mechanisms underlying progerin-induced atherosclerosis remain unexplored, in part due to the lack of appropriate animal models. First author Dr Hamczyk, corresponding author Dr Andrews, and colleagues from CNIC in Madrid performed an elegant series of experiments and generated not only the first mouse model of progerin-induced acceleration of atherosclerosis, but also provided the first direct evidence that progerin expression restricted to vascular smooth muscle cells but not to macrophages was sufficient to induce premature atherosclerosis and death. Progerin-induced loss of vascular smooth muscle cells caused atherosclerotic plaque destabilization that led to myocardial infarction. Ubiquitous and vascular smooth muscle cell specific progerin expression increased LDL retention in aortic media, likely accelerating atherosclerosis.
The next original paper implicates dysregulation of mitochondrial dynamics as a therapeutic target in human and experimental pulmonary arterial hypertension. Now, mitotic fission is increased in pulmonary arterial hypertension. The fission mediator, dynamin-related protein 1, or Drp1, must complex with adaptor proteins to cause fission. In the current paper from co-first authors Dr Chen and Dasgupta, corresponding author Dr Archer from Queens University in Ontario Canada, and colleagues, the authors examined the role of two recently discovered but poorly understood Drp1 adaptor proteins known as mitochondrial dynamics protein of 49 and 51 kilodalton. They found pathological elevation of these mitochondrial dynamic proteins in pulmonary artery smooth muscle cells and endothelial cells in both human and experimental pulmonary arterial hypertension that accelerated mitotic fission and supported rapid cell proliferation. Mitochondrial dynamics protein's expression was epigenetically upregulated by a decreased expression of microRNA-34a-3p. Circulatory microRNA-34a-3p expression was decreased in both patients with pulmonary arterial hypertension and preclinical models, silencing the mitochondrial dynamics proteins or augmenting microRNA-34a-3p regressed experimental pulmonary arterial hypertension, thus, proving to be potential new therapeutic targets for pulmonary arterial hypertension.
Dyslipidemia guidelines currently recommend that non-HDL cholesterol and apolipoprotein B, or apoB, are secondary targets to the primary target of LDL cholesterol. However, how frequently does non-HDL cholesterol guideline targets change management, and what is the utility of apoB targets after meeting LDL and non-HDL targets?
Well, answers are provided in the next paper from first author Dr Sathiyakumar, corresponding author Dr Martin, and colleagues from Johns Hopkins University School of Medicine. These authors analyzed more than 2,500 adults in the US National Health and Nutrition Examination Survey, as well as more than 126,000 patients from the Very Large Database of Lipids Study with apoB. They identified all individuals as well as those with high-risk clinical features, including coronary disease, diabetes, and metabolic syndrome who met the very high and high-risk guidelines targets of LDL cholesterol of less than 70 and less than 100 mg/dL, respectively, and this was measured using either the Friedewald estimation or a novel, more accurate method. They found that after using the more accurate method of estimating LDL cholesterol, guidelines suggested non-HDL targets could alter management in only 1 to 2% of individuals, including those with coronary disease and other high risk clinical features.
However, using the Friedewald estimated LDL cholesterol gave a much higher percentage. Among all individuals with both LDL cholesterol less than 100 and non-HDL cholesterol less than 130 mg/dL, only 0-0.4% had an apoB above or equal to 100 mg/dL. Thus, the utility of current non-HDL targets appears to be contingent on the accuracy of LDL cholesterol estimation. When using a novel, more accurate estimation method to assess LDL cholesterol, the non-HDL cholesterol is infrequently above current guidelines' suggested targets after the LDL target is met. Current guidelines suggest that apoB targets also provide only modest utility after cholesterol targets are met. These findings were robust to high-risk clinical features, sex, fasting status, and presence of lipid-lowering therapies.
The final paper tells us that HIV infection increases the risk of developing peripheral artery disease. Dr Beckman from Vanderbilt University Medical Center and colleagues studied almost 92,000 participants in the Veterans Aging Cohort Study from 2003-2014 over a median follow-up of nine years. They excluded participants with known prior peripheral artery disease or prevalent cardiovascular disease. They found that infection with HIV was associated with a 19% increased risk of incident peripheral artery disease beyond that explained by traditional atherosclerotic risk factors. Once peripheral artery disease had developed, HIV infection increased the risk of mortality compared to uninfected patients. Whereas for those with sustained CD4 cell counts above 500, there was no excess risk of incident peripheral artery disease events compared to uninfected people. Furthermore, worsening HIV infection as measured by CD4 cell count and HIV viral load was associated with increased incident peripheral artery disease and mortality. In summary, HIV infection increased the risk of developing peripheral artery disease and mortality. The findings also suggest that aggressive antiretroviral therapy to reduce viral load and increase CD4 cell counts may reduce the risk of developing peripheral artery disease. Furthermore, clinicians should solicit clinical complaints and physical signs consistent with peripheral artery disease to facilitate the diagnosis of peripheral artery disease in patients with HIV and ensure the addition of guideline-based anti-atherosclerotic therapies in these patients.
Well, that wraps it up for our summaries. Now for our feature discussion.
When it comes to acute ischemic stroke treatment, we've learned from trials of intravenous thrombolytics that time is brain. But what about the situation with endovascular treatment of strokes? Also, what's the situation like in the real world? Well, today's featured paper really provides precious data telling us about time-to-endovascular treatment and outcomes in acute ischemic stroke. I am so delighted to have with us the first and corresponding author of the MR CLEAN Registry, Dr Maxim Mulder from Erasmus University Medical Center, as well as our editorialist, Dr Micheal Hill, from University of Calgary, and our associate editor, Dr Graeme Hankey, from University of Western Australia, all here to discuss this hugely important topic.
Maxim, could we start with you? So, MR CLEAN Registry means there was a MR CLEAN trial. Could you tell us a little bit more about your paper?
Dr Maxim Mulder: Sure, well to start with, I think it's important to make sure all the people know the difference between the MR CLEAN trial and the registry since of course the trial was to show whether the intra-arterial treatment is effective when it comes to acute ischemic stroke treatments and then, of course, for people treated within six hours. When the MR CLEAN trial finished we continued in the Netherlands with all the participating centers from the trial to gather all the data from everybody who is treating in the whole country with the intra-arterial treatment, but they're not anymore in the light of the trial but in the clinical practice. We've had a lot of trials, but we don't have a lot of clinical practice date yet of the intra-arterial treatment, so that's where it all started.
So, what we found is we consider our data, so with the least possible selections or the only selection was basically to treat within six and a half hours and have patients that had a proven large vessel occlusion that were treated in the Netherlands and of course as we also know from when intravenous therapy was introduced that what happens in clinical trials doesn't necessarily happen when a new treatment is introduced into clinical practice. There are less strict criteria for patients to get treated, and you know everybody, of course, there is a lot of debate about which patients should be treated. In clinical trials it is very strictly coordinated, but in clinical practice there's a lot more room to have an interpretation and also treat a different population. So, we also see that our population is somewhat older and has more comorbidities than in all the trials. Also what we found, of course, our most important finding was that when compared to all the trials or the large trials combined together in the Emberson analysis about time that when we look at the influence or the association of time with functional outcome of intra-arterial treatment that this association is clearly stronger than we found in the previous, the trial data.
So, I think that's a very important finding. Also, for everybody who's now treating this patient in clinical practice.
Dr Carolyn Lam: Exactly. I mean this is really stunning results. If I could paraphrase from your paper, every hour delay in time from stroke onset to the start of endovascular treatment resulted in a 5.3% decreased probability of functional independence and a 2.2% increase in mortality. This is stunning. Thank you, thank you for publishing these results with us in Circulation. I would like to ask Michael, I love the point you made in the editorial that time of stroke onset is really quite a difficult thing to determine. Could you tell us your thoughts about that, Michael?
Dr Micheal Hill: I mean, it's something like 15-20% of the time stroke is unwitnessed, either because stroke occurs in sleep and the patient is discovered with their stroke symptoms on awakening. Or the patient is simply alone and has their stroke unwitnessed by any bystander. Even in so-called witness stroke, there are probably significant errors in determining the exact time of stroke onset because it's an emergency, and everybody's flustered and time anchors are not necessarily well known. And, so, I think it's an important point that the actual measurement of time is challenging, yet it's still an easier clinical tool for us to use in gauging the extent or evolution of stroke. That's the most important thing to point out here is that this population effect that Max has observed in the MR CLEAN registry is certainly concordant with clinical trial data.
I certainly think it's correct, and, as you pointed out in your comments, dramatic, but a really important issue is that for the individual patient, there's quite a lot of variance in the evolution of stroke. So, whereas, on a population basis, it's absolutely true that the average time from estimated time of stroke onset to treatment initiation is absolutely critical; in some patients, the individual might be still a good candidate for treatment even in late time windows, and some patients, even after a couple hours, the damage is already extensive, and they may not be good candidates for treatment. It still requires individual decision making, and it still leaves a lot of room for clinical judgment largely based on imaging.
Dr Carolyn Lam: True, and I think you've really succinctly put that solid take-home message in the title really, which is acute ischemic stroke biology really demands fast treatment. I think that's the one thing that we'd really like clinicians to come away with. You agree?
Dr Micheal Hill: Absolutely. Especially, I think, the advantage of looking at whole populations and large, I mean this is a large registry, the MR CLEAN registry, and the group should be congratulated because it's clearly the biggest registry in the world right now of available data, and it's only getting larger week by week as they carry on with their work. You know the whole Netherlands group, the MR CLEAN group, are a fantastic group, but absolutely right, on a population basis, we absolutely have to get our systems in place so that on average we're treating patients incredibly fast. On an individual basis, the clinicians and the teams treating an individual patient still need to make judgments about that patient's eligibility for treatment. It's easy when the times are fast, so if you're an hour and a half from onset, nearly everybody's gonna be a good candidate for treatment, but as time elapses you need to make judgements on the basis of imaging.
Dr Carolyn Lam: Well put. You know, Graeme, you're over there in Australia. What are your take-home messages about how generalizable these findings are to places outside perhaps of the Netherlands?
Dr Graeme Hankey: I think you're asking about the external validity. I think the internal validity is certainly there. As Michael said, this is the largest registry that we have that's been published data on this before. It's certainly novel, and we're very confident that the results are valid, although this is an observational study and not a randomized trial. The association between time and outcome seems to be independent of the major patient factors that may influence time to endovascular therapy. For example, younger people who are less frail and they're alert and they're mobile can get to treatment earlier. So, you might say, well of course they're gonna have a better outcome. But these factors were adjusted for. And, of course, there are procedural factors that could influence the association between time and outcome, but we're very confident in the results and the novelty of them in supporting and building on the randomized trial data.
We're also very confident in the registry and the nature of the population. The results are likely to be generalizable beyond the Netherlands population where this was conducted in routine clinical practice, certainly across Caucasian populations that are similar and with similar stroke interventional and assessment protocols, and I would hope to see this sort of study validated externally in other populations. But, also, as Michael said, I think this study not just highlights the importance of time as a factor and its implications for systems of care and recognizing people with disabling stroke and ensuring they’re assisted urgently to the appropriate imaging but also to acknowledge that time isn't the only factor. And as Michael has alluded to, our brain tissue has different collateral circulations and different probable genetic factors and metabolic factors. So, someone with a stroke at one hour, it might be all over for them. Whereas, another person with a stroke at 24 hours ago, they might have salvageable tissue.
So, although, generally time is an important prognosticator as we've learned here, there are probably other factors that need to be considered and accounted for. But this certainly takes us a step forward, and, in answer to your question, I think we have confidence in its generalizability.
Dr Carolyn Lam: Thank you Graeme. Maxim, in line with that, are there any next steps you plan?
Dr Maxim Mulder: In light of the most recent trials, the DAWN and DEFUSE 3 trial about 6 to 25-hour, 24-hour window, I think that both of the trials are very exciting, and they shine a new light into a new set of patients that are still able to offer a great benefit intra-arterial treatment. In my opinion, the most important thing, especially in those two trials, those are highly selective patients, especially selected on all the extra imaging parameters, and I guess that there's a whole larger population that could still benefit in this time window and that's also one of the things we're currently studying in one of our new trials in the Netherlands in the MR CLEAN-LATE trial, and that is randomizing patients who are having a large vascular occlusion 6 to 24 hours, and the only extra criteria they should meet is they should have at least a little bit of collateral circulation on the ischemic brain side.
Dr Carolyn Lam: Michael and Graeme, what do you think are the priorities for next steps in research.
Dr Micheal Hill: I guess overall in the field, I don't think there's any doubt that faster treatment is better. What we need to do across the world is make sure that everybody's receiving it on a system-wide basis. Right? I think there needs to be a lot of more careful work done on getting systems of care in place to make sure that patients are getting the treatment they can get. We have very many weaknesses. Some are related to lack of accreditation. Some are related to the resources required to get people treated quickly. Some are related to continuing resistance in some specialties to even giving intravenous thrombolytic drugs. So, I think faster treatment in general for acute stroke is a theme; it's not just limited to endovascular treatment. It's treatment for patients for intravenous thrombolysis. It's also actually true for TIA and minor stroke. We've had recent data on fast antiplatelet therapy, so, it's not an emergency in the same way in terms of minutes, but it's still a general theme of acute stroke care.
We need to be like the Ferraris and the Formula One, right? And get ourselves moving. That's a big challenge for people. Right? It's a big stress on systems. But, I think there are other examples in medicine. We've seen this evolution in acute coronary care, and we've seen the evolution in acute trauma care. In many ways, the next things that need to really continue to happen are publications like this and getting the message out that people need to start changing their mind. The biggest thing that I find when I talk to people or talk at meetings or talk to administrators is that they say, "Well, we can't do this many CTs that fast. We can't respond that fast." And the answer is actually that you can't change the biology of the disease, so if you decide you wanna treat stroke patients, you better figure out how to change your systems. It's a question of will here rather than trying to bend the disease to the system.
Dr Carolyn Lam: Wonderfully put. Can't change the biology so we better change the systems. How about you, Graeme? Any last words?
Dr Graeme Hankey: Just to concur with Michael’s comments there and Max's underlying theme that time is very important. And as Michael alludes to, it's not just acute ischemic stroke due to large vascular disease, it's also acute intracerebral hemorrhage. We're learning now really if we're gonna have an effect in the bleeding brain probably we have to do that within the first three hours and maybe not be waiting so late. And as Michael alludes to, someone with a minor ischemic stroke who's had a hot volcano gone off in their neck, as you know, ruptured atherosclerotic plaque, it's like those volcanoes in Hawaii, they're gonna keep going off again. And the risk is 5% in the next two days and 10% in the next week. So, a TIA and a mild ischemic stroke, it is a medical emergency to find the cause and to get it treated, and that's why the synopsis of this message from Max's study is that people, if they do avail themselves of acute assessment early, even if they don't have a large vessel occlusion causing an ischemic stroke, they may actually have their intracerebral hemorrhage treated quickly or, more evidence based at the moment, their TIA or mild ischemic stroke have the cause ascertained and treated emergently and reduce that early risk of recurrence should they survive.
Dr Carolyn Lam: Excellent points. Thank you so much, gentlemen. This has been an amazing podcast.
Thank you so much for joining us today. Don't forget to tune in again next week, listeners.