Dr. 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 week's issue, we are discussing if public placement of defibrillators in the community can be improved. First, here's your summary of this week's Journal.
Stroke incidents, prevalence, and risk factors have been changing over the past 50 years so do we need a more contemporaneous revised Framingham Stroke Risk profile to reflect these trends? Well the first paper in our issue looks at this and this is from first author Dr. Dufouil, corresponding author Dr. Seshadri and colleagues from the Boston University School of Medicine.
Let's first recall that the Framingham Stroke Risk profile was originally described in 1991 and integrates the effect of age, sex, and baseline measurements of various vascular risk factors such as systolic blood pressure, use of anti-hypertensive medications, left ventricular hypertrophy on ECG, prevalent cardiovascular disease, current smoking status, atrial fibrillation and diabetes all to describe the 10-year probability of incident stroke.
In the current paper, the authors updated the Framingham Stroke Risk profile using the means of risk factors that reflect current prevalence, the estimate of incident stroke to reflect current rates, and the hazards ratio that reflect current associations. They used the same risk factors identified in the original stroke risk profile with the exception of left ventricular hypertrophy. The authors compared the accuracy of the standard old risk profile with the revised new risk profile in predicting the risk of [alt 00:01:58] and ischemic stroke and validated the new risk profile in two external cohorts, the three cities and regards or reasons for geographic and ethnic differences in stroke studies.
They found that the new stroke risk profile was a better predictor of current stroke risks in all three samples than the original old Framingham Stroke Risk profile. The new stroke risk profile was also a better predictor among whites compared to blacks in the regard study. The authors therefore concluded that a more contemporaneous revised Framingham Stroke Risk profile could serve as the basis for examining geographic and racial differences in stroke risk and the incremental diagnostic utility of novel stroke risk factors.
The next study provides preclinical proof of principle that an apelin receptor agonist may be of therapeutic use in pulmonary arterial hypertension. And the agonist in this case is Elabela/Toddler or ELA, first identified as an essential peptide in the development of the heart in Zebrafish, and subsequently proposed as a second endogenous ligand at the G-protien coupled apelin receptor, which works at this receptor despite a lack of sequence similarity to the established ligand, apelin.
In this study from first author Dr. Yang, corresponding author Dr. Davenport and colleagues from University of Cambridge in the United Kingdom, ELA competed for binding of apelin in human hearts with overlap of the two peptides indicated by encyclical modeling. ELA activated G-protein and β-arrestin dependent pathways and as expression was detectable in human vascular endothelium and plasma. Comparable to apelin, ELA increased cardiac contractility, ejection fraction, cardiac output, and elicited vasodilatation in rats in vivo.
ELA expression was reduced in cardiopulmonary tissues from patients with pulmonary arterial hypertension and in rat models. Finally, ELA treatment significantly attenuated the elevation of right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary vascular remodeling in monocrotaline exposed rats. Thus, these results suggest that a selective agonist that mimics the action of indulgence ligand apelin or Elabela/Toddler, ELA, may be a promising therapeutic strategy in the treatment of pulmonary arterial hypertension.
The final paper looks at sudden cardiac death after coronary artery bypass grafting, its incidents, timing, and clinical predictors. First author Dr. Rao, corresponding author Dr. Velazquez and colleagues from Duke Clinical Research Institute in Durham, North Carolina, looked at the patients enrolled in the STICH, or Surgical Treatment of Ischemic Heart Failure Trial who underwent coronary artery bypass grafting with or without surgical ventricular reconstruction. They excluded patients with a prior ICD and those randomized only to medical therapy. Over a median followup of 46 months, 113 out of 1,411 patients who received coronary artery bypass surgery, had sudden cardiac death while 311 died of other causes.
The five-year cumulative incidence of sudden cardiac death was 8.5%. In the first 30 days after bypass surgery, sudden cardiac death accounted for 7% of all the deaths. The numerically greatest monthly rate of sudden cardiac death was in the 31 to 90 day time period. In multivariable analysis end-systolic volume index and BNP were the most strongly associated with sudden cardiac death. Thus, this study shows that the monthly risk of sudden cardiac death shortly after bypass surgery among patients with a low ejection fraction is highest between the first and third months, suggesting that risk stratification for sudden cardiac death should occur early in the post-operative period, particularly in patients with an increased preoperative end-systolic volume index and/or an increased BNP.
Well, that wraps it up for you summaries, let's turn to our feature paper.
I love our feature paper this week. You know why? It actually tells us what Tim Hortons, Starbucks, Second Cup and ATMs may have in common and may have to do with sudden cardiac death. Indeed, our feature paper actually tells us that coffee shops and ATMs may be the best spots to place AEDs at, well at least in Toronto. And to discuss this really interesting paper, I have the corresponding author, Dr. Timothy Chan from University of Toronto as well as Dr. Sana Al-Khatib, welcome again Sana, Associate Editor from Duke University, welcome to you both.
Dr. Al-Khatib: Thank you, my pleasure.
Dr. Chan: Thank you, very nice to be here.
Dr. Lam: So Tim, was that an interesting enough lead up? I mean you have to tell us about your study, it is so fascinating.
Dr. Chan: I'm very pleased that you find it interesting and not just us. So we undertook this study, we started this actually a couple of years ago, and we've been working on this issue of defibrillator location optimization for several years, and we've been talking and we have meetings in coffee shops and we were just wondering one day, what would be the risk or the coverage provided by all these different well-recognized location types around the city, and that was really the motivation that got us started looking at this study.
Dr. Lam: Tell us what you did and also how it differs from the study you did that was published in 2016 where you also reported on the spatial temporal analysis of registered AEDs in Toronto. The current study clearly extends it, but could you clarify to us all how it does?
Dr. Chan: Maybe just give a little bit of a background and context with regards to other literature that's similar. There have been studies in the past that looked at what we would call spatial coverage of cardiac arrest, so they looked at different broad location types and they tried to calculate, they basically calculated how many cardiac arrests happened, let's say within 100 meters of those location types. And what we've done here is we've extended that in a couple of directions. The first direction is looking at spatial temporal coverage and so this is not just in the nearby vicinity, IE, 100 meters, but also that cardiac arrests happen when that nearby location that had the AED was open. So if a cardiac arrest happens, but for example, let's say there's a coffee shop that actually has an AED and that coffee shop is closed, it's almost as if that AED is not even there. So one of the major things we made sure to include was this idea of temporal coverage as well, on top of the spatial.
The second major difference I would say would be the fact that we're really looking at more granular location types, so you mentioned a few businesses in your opening such as Tim Hortons and Starbucks and so on, which are coffee shops, and so one of the things that we find is when we look at very broad location types, we tend to aggregate together lots of different types of businesses. For example, if you think about a restaurant, there are many different types of restaurants that get lumped in to this category, and they do have different cardiac arrest coverage associated with them. So by breaking it up into smaller location types, we wanted to get a better idea of the risk at different locations and if you also think about one of the long term goals of this work would be to try and help policy makers identify promising partners to partner with for, let's say public access defibrillation programs, by identifying specific businesses or municipal locations, it might actually give them better targets to try and pursue rather than let's say a group of different businesses.
Dr. Lam: That makes so much sense and it really just seems like such an important public health message as well. The sensible part being of course, if you have an out of hospital cardiac arrest, you need an AED that's both nearby and available, so that was really clever. Sana, could you give us your take on the public health implications of Tim's findings?
Dr. Al-Khatib: I think the public health implications of this work can be vast and if you look at what he's done in terms of ascending to out of hospital cardiac arrests a lot of initiatives have been launched to try to improve the outcomes of patients who have the out of hospital cardiac arrests. Unfortunately despite all the work that has been done and all the wonderful initiatives that have been launched, we still have a lot of work to do to improve the survival of those victims. So certainly a crucial step is how we deploy AEDs in a strategic way based on data and evidence such as these data that are provided to us by Tim and his colleagues.
I think this is very clever, I do agree that we have to be more strategic in how we deploy AEDs and having the data such as these will only help us improve and get better of course. Everybody has limited resources, and so if we can be more selective in terms of how we deploy AEDs I think that would help everybody. I realize this was done within Toronto and some of these findings may not be generalizable to other cities, but I think this is definitely a great way to make us reshape our thinking in terms of how we do this, and so a question I have for Tim if I may, are you aware of any similar studies that have been done looking at this in other cities and then if not, how do we encourage other groups to do similar work?
Dr. Chan: There have been similar studies done that have focused really on the spatial side of things, so doing this 100 meter radius and counting cardiac arrests that have been nearby, there's actually been fairly little work that's been done on the spatial temporal side. And a couple of exceptions that I will note that I think are important to point out is there was a very nice study that was done out of a group in Copenhagen, and they were looking at actually spatial temporal coverage, particularly the loss in coverage that you experience when you go from looking at spatial to spatial temporal. For example if you count all of the cardiac arrests that happen nearby a registered AED based only on 100 meters, and then you count the same number, but you have to now layer on top of that when the building that the AED is in is open, then you tend to get a big loss. They found quite striking numbers, I think they found a 50% loss, when you look at evenings and weekends I believe, in Copenhagen. So basically all the cardiac arrests that happened where you thought there was an AED nearby, there's actually only one in two is actually nearby and accessible when you looked into hours of operation.
And this actually comes back to the earlier question from Carolyn about how our study relates to our previous study in 2016, so we actually replicated that Copenhagen study in Toronto where we measured spatial coverage and we measured spatial temporal coverage and we measured that loss, and we found a similar loss overall, about 20%, so 1 in 5 cardiac arrests happened where there was an AED nearby, but that AED was not available because that location was closed. So that was one of the impetuses for leading us to do this study where we start to examine specifically the different location types and the specific businesses that were involved.
Dr. Lam: Wow, that's just really inspiring Tim, I mean I'm kind of thinking about the Singapore situation too and I think it's actually applicable and I would love if we had local data similar to yours, so congratulations, I really share what Sana said. Thinking though about the public health and the larger implications of what you're talking about, what do both of you think of the implications for a public commercial partnership in these things if it is coffee stores or banks that seem to be the best locations, perhaps these have implications to how the public and private should collaborate to make these things happen, what do you think?
Dr. Chan: I completely agree. These types of public private partnerships, specifically for AED deployment are not necessarily new, they already happen in some parts of the world. One of the examples I always like to bring out is if you go to Japan and they have vending machines everywhere in Japan and then you'll often run into vending machines that have an AED right in them, so one of the benefits is that first the vending machines are everywhere and second, if you're a citizen there, you probably know where the vending machines are where you travel in your day to day life and so I would say that would be a very similar thing here in North America, whether it be coffee shops or ATMs, if someone were to put me in a random part of the city and ask me, "Hey Tim, do you know where the nearest AED is?" I'd probably have a lot of trouble, but if they said could you figure out where the nearest ATM is for your bank or where the nearest Starbucks is you know, there's pretty much one on every corner. It would be much easier to identify and find, so I think there are significant benefits to partnering with these companies or these businesses that have very broad name recognition and brand recognition, are geographically well spread and located in populated areas.
I should also mention, I feel like there's a few other benefits for these types of locations, so for example for ATMs, I think there's a lot of secondary benefits, so for example, there's a built in security component, there's a video camera there, that might be able to help make sure that no one's vandalizing or stealing an AED. There's perhaps built in weather protection because there's electricity there already, so in a cold climate like Toronto where you might worry about putting an AED outside, you could have potentially a heating cabinet that would be fed by the electricity for the ATM and so on. So I think there's actually a lot of benefits if we could actually operationalize a system like this.
Dr. Lam: Sana, do you think there are some more unanswered questions?
Dr. Al-Khatib: I did want to agree with Tim on what he said, that these public private partnerships have been in place. Unfortunately we haven't been able to make much progress. As I said, I do see the results of this study as being potentially a catalyst to improve the work that we are doing and ensuring stronger partnerships and collaborations to help us achieve what we want to achieve which is basically improve the survival rate of out of hospital cardiac arrests, so I completely agree with that and I loved your idea, Tim, when you talked about now people may not recall where AEDs might be, but if you link them with teller machines or coffee shops, I think that would be much easier to remember.
You know of course there are a lot of questions that remain unanswered unfortunately. Again as was stated by Tim and his colleagues in the paper and on the call, how we can translate these findings to other locations I think is really key and then of course doing the work, meaning let's use these data to deploy more AEDs and then really looking at the impact of that. Ultimately we want to make sure that if we hypothesize that by doing this we can improve outcomes for these victims, we would want to prove that. So I think the next steps would be to see if this can be replicated in other places, but also even within Toronto, if we can accomplish some of this and then examining the impact, I think would be extremely beneficial.
Dr. Lam: Fabulous, thank you so much Sana, thank you so much Tim for sharing your thoughts today.
Listeners, you heard it right here on Circulation on the Run. Don't forget to tell all your friends about this podcast and tune in next week.
Caroline: Welcome to Circulation On The Run! Your weekly podcast, summary, and backstage pass to The Journal and it's editors. I'm Doctor Carolyn Lam, Associate Editor from the National Heart Center in Duke National University of Singapore. What does the gut microbiome have to do with Cardiovascular Disease? Well to find out you'll just have to stay tuned for our featured discussion debate. First, here's our summary of this week's journal.
The first paper seeks to answer the question "does first trimester screening modify the natural history of Congenital Heart Disease?" To answer this question Doctor Jasinskyl and colleagues from the University Hospital in Masaryk University in the Czech Republic, analyze the spectrum of congenital heart defects and outcomes of 127 fetuses diagnosed with congenital heart defects in the first trimester compared to 344 fetuses diagnosed in the second trimester screening. All of these analyzed between 2007 and 2013.
They found that the spectrum of congenital heart defects diagnosed in the first versus second trimesters differed significantly with a greater number of comorbidities, defects with univentricular outcomes, intrauterine deaths, and terminations of pregnancy in those diagnosed in the first compared to second trimester.
They further analyze 532 fetuses diagnosed with congenital heart defects in the second trimester but in an earlier period of 1996 to 2001, which is the period before first trimester screening was introduced. In this group they found significantly more cases of defects with univentricular outcomes, intrauterine deaths, and early terminations of pregnancy. In comparison to fetuses also diagnosed with congenital defects in the second trimester but in the later period of 2007 to 2013.
Thus, the authors concluded that first trimester screening had a significant impact on the spectrum of congenital heart defects and on the outcomes of pregnancies with defects diagnosed in the second trimester. Early prenatal cardiac ultrasound screening may therefore, in some countries, reduce the number of children born with severe cardiac abnormalities and associated comorbidities.
The next study sheds light on the use of intravenous recombinant tissue plasminogen activator, or "RTPA," in patients with acute ischemic stroke also receiving no wax or the newer oral anticoagulants. Doctor Sienne and colleagues from the Duke Clinical Research Institute in Durham, North Carolina use data from the American Heart Association "Get With The Guidelines" stroke registry in 42,887 ischemic stroke patients treated with RTPA at 1,289 hospitals in the United States between 2012 and 2015. They basically found no statistically significant differences in the risk of symptomatic intracranial hemorrhage between patients who were taking Noac, Warfarin, or not taking any anticoagulant before the stroke.
This largest clinical experience of stroke thrombolysis in patients receiving Noac before the strokes thus suggest that RTPA is reasonably well tolerated without prohibitive risks for adverse events amongst selected Noac treated patients. However, the authors are quick to say that their observations must be considered as preliminary due to the absence of coagulation parameters, timing of the last Noac intake, and whether or not non-specific reversal strategies may have been applied.
The next paper provides experimental evidence of the unique effects of plasminogen activation and Alpha 2 antiplasmin inactivation on the fibrinolytic system in pulmonary embolism. In this paper from Dr Sing, Hong, and Reed from the University of Tennessee Health Sciences Center in Memphis, Tennessee the authors use mouse models of experimental pulmonary emboli to show that monoclonal antibody inactivation of Alpha 2 antiplasmin, which is an endogenous inhibitor of plasmin, effectively dissolved pulmonary emboli with similar potency to high dose RTPA.
Alpha 2 antiplasmin inactivation synergize with low dose RTPA to enhance thrombus dissolution. And like RTPA, Alpha 2 antiplasmin inactivation alone or in combination with low dose RTPA, did not cause fibrinogen degradation or increased bleeding. The authors therefore concluded that Alpha 2 anti plasmin is a dominant regulator that prohibits thrombus dissolution in vivo.
Therapeutic modulation of Alpha 2 antiplasmin activity may therefore prove an effective strategy to enhance fibrinolysis without significantly increasing the bleeding risk. These results are discussed in an accompanied editorial by Doctor Yurano from Hamamatsu University School of Medicine in Japan.
More exciting experimental data in the next paper showing that novel beta arrestin signaling pathways may be viable targets in dilated cardiomyopathy. First author Doctor Reba, corresponding author Dr Solaro, and colleagues from University of Illinois at Chicago treated a dilated cardiomyopathy mouse model expressing a mutant tropomyosin for three months with either a beta-arrestins two biased ligand of the entertance and receptor or losartan and angiotensin receptor blocker as control. Treated mice showed improved cardiac structure and function associated with myofilamins that had significantly improved myofilament calcium responsiveness. Which was depressed in the untreated mice.
These functional changes were mediated through beta arrestin which may have a novel role in increasing MLC2V phosphorylation through a previously unrecognized interaction of beta arrestin localized to the sarcamore. Thus, long term beta arrestin 2 biased agnonism of the angiotensin receptor may be a viable approach to the treatment of dilated cardiomyopathy. Not only by preventing maladaptive signaling but also by improving cardiac function by altering the myofilament calcium response via beta-arrestin signaling pathways. The concept of a two in one angiotensin receptor blocker and calcium sensitizer is discussed in accompanying editorial by Doctors Wu, Ju, and Siao from Peking university in China.
The final paper asks the question "are three arterial graphs better than two coronary artery bypass grafting?" Doctor Galdino and colleagues from Weill Cornell Medicine in New York performed a meta analysis of eight propensity score matched observational studies on more than 10,000 matched patients comparing the long term outcomes coronary artery bypass grafting with the use of two verses three arterial graphs.
They found that the use of a third arterial condo et in bypass grafting is a associated with superia long term survival irrespective of sex and diabetes status and without a higher operative risk. These results therefore support a strategy of the use of a third arterial graph and really deserve confirmation in prospective randomized trials. Well, that's it for the summaries. Let's welcome our guests.
Our topic for discussion today is so exciting. In fact, I am going to read from the paper describing it as an exciting, new, and important field of investigation where we start to understand how nutrition, our gut micro-community composition, and our genetics actually all play a part in Cardiovascular Disease. And to discuss this paper I have the first and corresponding author Doctor Wilson Tang from Cleveland Clinic Foundation as well as Doctor Nikhil Munshi, Associate Editor from UT Southwestern. Welcome Wilson and Nik!
Nik: Thank you.
Wilson: Thank you.
Caroline: Wilson, please set the stage for us! What does our gut microbiome have to do with cardiovascular disease? I agree it's a hot area but, you know, could you just describe what it actually means.
Wilson: This has been somewhat of an accidental discovery from our group when we start encountering different types of metabolites that we measure to kind of associate them with Cardiovascular Disease. And unbeknownst to us, some of them are produced by the bacteria that live inside us to which we convert and try to eliminate. So one such metabolite that we identify is, which in many of the foods that we tell our patients, advise our patients that have high risk of Cardiovascular Disease. So all these connections come together to form a scientific basis to which how one of the biggest environmental exposures that we have which is what we eat every day is filtered by trillions of bacteria that live inside us and many of these metabolites become hormones that effect our every day function and activity.
And, in many ways, can actually lead to diseases that are so remote from the gut but such as Cardiovascular Disease, Atherosclerosis, and we further identify these process and they impact downstream organ function like heart function and kidney function. So these are all very excited areas and this is just one of several metabolites. There are other metabolites that also impact blood pressure and even brain function and so all these areas become kind of a new avenue for us to look at potential therapeutic targets.
Caroline: Yeah I think it's so completely fascinating that we can actually each experience a given meal differently based on the different types of gut microbial communities in our bodies isn't it? And that that actually can effect things all the way from atheroscleroses, to obesity, insulin resistance, and so on. Could you give us a specific example from your research?
Wilson: We actually identified a metabolite, a very small molecule called Trimethylamine N-oxide, we abbreviate it as TMAO. And TMAO is actually formed from the bacteria from a precursor called Trigosamine which is, you know, gas. In other words, the bacteria taken substances of nutrients such as choline and connetine which is actually common in many foods but particularly in red meats, in egg yolks, and many other foods that we know are potential contributors to Cardiovascular Disease.
And actually converted into this gaseous compound that our liver converted into a neutral compound, that we think is neutral for a long time and nitrogenous waste, except that when we have both animal studies and human studies patients with high levels of this TMAO metabolite has been associated with a high risk of Cardiovascular Disease. And in fact in animal studies we have direct evidence that show its contributing to the mechanistic compartment.
Caroline: Now extrapolating from what you just said so vegetarians, for example, or vegans even more so, would have less TMAO levels then?
Wilson: Yeah, obviously there are wide variation in these levels actually change almost by the minute because obviously we eat different times of the day and it comes in and out of our bodies. But in general, yes, in other studies that we actually identified a higher level of in carnivores which are meat eaters verses vegans and vegetarians who do not eat meat.
Wilson: Yeah and we actually use... I sort of labeled choline and connetine to actually directly show that the synthesis of TMA and TMAO by a labeled connetine is higher in meat eaters, carnivores, verses vegetarian or vegans.
Caroline: Oh, I really have to ask both you Wilson and Nik the following question then. What do you think is the, you know, take home message? How do you apply this clinically and even more cheeky, perhaps, how are you applying this in your own life? I mean with this knowledge have you become vegetarian? I'm putting you on the spot here.
Wilson: I think this is basically a very scientific demonstration of how what we eat does impact our every day bodily function. And I think many cultures have this identification. Obviously many Asian cultures have seen the impact of food. In fact, it actually opens entire insight into how different medicinal food may actively be impacting the gut microbiome that actually creates different effects in the body. But in terms of diet and nutrients, yeah I have totally have eaten less meat in my every day dietary habits.
I definitely think it's something that is certainly quite insightful and probably very impactful. That being said, I think different cultures also have different populations of microbiome and I think it's not a one size fits all. In fact I think every individual has his own dynamic ranges and we are still in the very very first early stage of understanding how this impact helps in disease. So there's a lot of excitement and there's a lot of technology that hopefully can help us to unravel this mystery.
Caroline: Exactly, a new and important field just like you said. Nik, what do you think?
Nik: From my standpoint, I'm actually not a big meat-eater so this was very welcomed news when this all came out. But, you know, from another standpoint it really opens up a lot of new questions. You know, it kind of blurs the line between sort of genetics and environmental factors. You know, so the questions of maybe a family who shares certain genetic traits may also share certain environmental traits. In other words, they share certain gut microbial components and maybe this sort of complicates how we're going to disentangle some of these risk factors going forward. I'm interested to get Wilson's take on this.
Wilson: Yeah it gives us a lot of insight to the I guess what happens is the microbiome is isolated in the family lineage because the lifestyle exposure are very similar in each household. So, what we thought is inherent is being inherited from both the genomic but also a microbiome perspective.
Caroline: Nik, you manage this paper. I really love, for example, that figure which I think everyone should get ahold of the journal and have a look at. Could you tell us a little bit more about this category of papers?
Wilson: I'm sort of charged with this task of bringing sort of basic Science across the aisle to clinicians so that we can all sort of talk the same language and perhaps interact on a higher level. And so I was really excited reading some of Wilson's work and you know I really wanted to bring that to some of our broad readership just so that we could sort of appreciate what sort of science was going and I really think that this is a really great example of something that's on the verge of being translated.
You know you can imagine that by either effecting certain metabolite compositions or maybe by treating certain subsets of bacteria we may be able to influence long term cardiovascular risks not to mention obesity, diabetes, and some of these other diseases that Wilson is actively working on. So I really read this with a lot of excitement and I wanted to bring this to a broader audience and you know we have a number of other articles that are in the pipeline that I think will serve to bridge this gap and put us on the same field so that we can kind of speak the same language.
Caroline: Wilson, did you have a good time sort of writing something like this its not long.
Wilson: It's actually very difficult. In fact, its just like writing poetry. You know it's hard to write in simple and short sentences. So it actually was a big challenge for me and I really thank the opportunity to be able to do that but I also want to emphasize I think it was a very insightful experience for me too. Because as a practicing physician and a commissioned scientist don't always merge these too few, these two areas in a way to actually see the importance we like to learn the science and try to explore I think clinicians really need to take charge and learn exciting science that's occurring. I think this is a wonderful avenue and I applaud [inaudible 00:18:10] for setting this radio [inaudible 00:18:11]
Caroline: Well listeners you heard it first here on Circulation On The Run it is poetry by Wilson Tang. So please, please pick up a copy of today's journal and don't forget to tune in again next week!
Dr. Carolyn Lam: Welcome to Circulation on the Run. Your weekly podcast summary and [inaudible 00:00:06] of the journal and its editors. I'm Dr. Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. In just a moment we will be discussing really fascinating preclinical data to suggest that high fiber diet and acetate supplementation may change the gut microbiota and thereby prevent the development of hypertension and heart failure. But first here's your summary of this week's issue.
The first paper describes the impact of heart transplantation on the functional status of children with end stage heart failure in the United States. First author, Dr. Peng, corresponding author Dr. Almond and colleagues from Stanford University, use the organ procurement and transplantation network to identify 1,633 US children age less than 21 years, and surviving one year or more post-heart transplant, from 2005 to 2014, with a functional status score available at three time points. Namely at listing, at transplant, and one year or more post-heart transplant. They found that at the one year assessment 64% were fully active with no limitations, or a functional status score of 10. 21% had minor limitations with strenuous activity, or a functional status score of 9. And 15% scored a functional status score lower than 9. Compared to the listing functional status, functional status at one year post-transplant increased in 91%, and declined or remain unchanged in 9%. Early rejection, older age, African-American race, chronic steroid use, hemodynamic support at heart transplantation, and being hospitalized at transplantation, were all associated with abnormal functional status post-transplant.
These findings may be helpful to patients, families, and referring providers by providing a contemporary picture of the post-heart transplant life in children as they weigh the risks and benefits of transplantation.
The next paper brings cardiac reprogramming one step closer to clinical translation. In this paper by first author Dr. Mohamed, corresponding author Dr. Srivastava, and colleagues from Gladstone Institute of Cardiovascular Disease in San Francisco, the authors used a high throughput chemical screen in post-natal mouse cardiac fibroblasts, and found that transforming growth factor beta, or TGF beta, and WNT, or wint inhibition, enhanced transcription factor based direct reprogramming of cardiac fibroblasts to induce cardiomyocyte like cells in vitro and in vivo. A combination of TGF beta and wint chemical inhibitors increased the quality, quantity, and speed of direct reprogramming, resulting in improved cardiac function after injury as early as one week after treatment. These chemical inhibitors enhanced human cardiac reprogramming and reduced the number of transcription factors needed for human cardiac reprogramming to just four factors. These findings if validated in large animals could facilitate a combined gene therapy and small molecule approach to heart failure.
The next study is the first report of the risks of cardiac mortality among five year survivors of childhood cancer beyond 50 years of age. First author Dr. Fidler, corresponding author Dr. Hawkins, and colleagues from University of Birmingham in United Kingdom, looked at the British childhood cancer survivors study, a population based cohort of 34,489 five year survivors of childhood cancer that was diagnosed from 1940 to 2006 and followed up until February 28th in 2014. The authors quantify the cardiac mortality access risk. Overall 181 cardiac deaths were observed, which was 3.4 times that expected. Survivors were two and half times more at risk of ischemic heart disease, and almost six times more at risk of cardiomyopathy or heart failure at death than expected. Among those aged over 60 years, subsequent primary neoplasms, cardiac disease, and other circulatory conditions accounted for 31%, 22%, 15% of all deaths. Specifically for cardiomyopathy or heart failure deaths, survivors diagnosed between 1980 and 1989 had 29 times the excess number of deaths observed per survivors diagnosed either before 1970 or from 1990 onwards. Thus the authors concluded that excess cardio mortality among five year survivors of childhood cancer remains increased beyond 50 years of age, and has clear messages in terms of preventative strategies. However, the fact that the risk was greatest in those diagnosed in 1980 to 1989, suggests that initiatives to reduce cardio toxicity among those treated more recently may be have a measurable impact.
The last study describes the 30 day results of the Source 3 Registry, that is the European Post Approval Registry of the latest generation of the Sapien 3 trans-catheter heart valve. Dr. Wendler and colleagues from King's Health Partners in London, describe that these 30 day results of the Source 3 Registry demonstrate that trans-catheter uratic valve implantation, or TAVI, using the Sapien 3 resulted in high procedural success with low procedural complications, and excellent post-implant hemodynamics. Moderate to severe paravalvular leakage appeared to be lower with the Sapien 3 than reported with prior versions of this trans-catheter heart valve. Rates of pacemaker implantation were higher with the Sapien 3 than in earlier generations of the valve. This, in combination with the growing experience of patient selection, procedure planning, execution, and post-operative care has led to one of the best short-term outcomes ever reported after TAVI. These results are discussed in an accompanying editorial by Dr. [Altassi 00:06:58], and Dr. [Urani 00:06:58], from the Emery Midtown Hospital in Atlanta, Georgia, where they say that these early results from Source 3 Registry are a source of encouragement with some caveats.
Well, those were your summaries. Now for our feature discussion.
I am so honored to have two lovely ladies join me today on the show. And they are the first author of a feature paper, Dr. Francine Marques from Baker Heart and Diabetes Institute in Melbourne, Australia, as well as Dr. Peipei Ping, associate editor from the David Geffen UCLA School of Medicine. Welcome ladies.
Dr. Peipei Ping: Hi, hello.
Dr. Francine Marques: Hi, thank you for having us.
Dr. Carolyn Lam: As a clinician, I have very very often advised my hypertensive patients to go on the dash diet. And you know, I have no had any trouble explaining the low salt bit, right? I understand it. But then I realize that I've always advocated as well the high fiber bit, not actually really understanding how high fiber directly impacts blood pressure. And I'm so excited because your paper, Francine, shed some light on this and it actually has something to do with the gut. So could you please explain what you did and what you found?
Dr. Francine Marques: So we fed a mouse model called [adoca 00:08:25] model of habitation, that also developed heart failure, we fed them a high fiber diet for three weeks, and then after that we did a surgery to make them become [habitant 00:08:36] safe and we followed them up for six weeks. And what we observed through that trajectory is that mice that were fed a high fiber diet had significantly lower systolic and diastolic blood pressure, and also an improvement in the heart function, and also a decrease in both heart and brainal fibrosis. And the reason why the fiber is so important is because although we usually don't digest the fiber, the bacteria in our gut absolutely love it. And that allows the bacteria, good bacteria to grow. And with that growth we have release of the fermentation of the fiber, releases in short chain fatty acid. So these specific molecules can then be put back into our body and can help us in our health. So we also fed these mice acetate, which is one of the short chain fatty acids, directly and we also observed very good improvements in blood pressure and cardiovascular health.
Dr. Carolyn Lam: It's just fascinating. So these are studies in mice. What do you think of clinical translational aspects of this?
Dr. Francine Marques: Large epidemialogical studies have shown that there is an inverse correlation between fiber consumption and blood pressure. And they have seen this through very small clinical trials looking into the intake of fiber lowering blood pressure. But our study opens the possibility of new interventions using maybe short chain fatty acids specifically, but are also looking into a different type of fiber. So most studies would look into either soluble or insoluble fiber directly. Our study, the diet that we used, is mostly resistant starches. So these are their preferred type of fiber for bacteria growth in our gut. And maybe they use a [inaudible 00:10:32] type of fibers as well could be a new [inaudible 00:10:36] opportunity.
Dr. Carolyn Lam: Peipei, I remember you discussing this paper at our editorial meetings and you so beautifully highlighted the novelty of this paper. Could you share this with our listeners?
Dr. Peipei Ping: Often within many complex studies trying to understand cellular pathways and mechanisms of cardio protection, it's a very important topic as we have had our research focus on in the pas t 25 years. What's very unique and provocative of this particular study is that it simply identified critical metabolic pathways that actually is underlying the protective effects. Many of us have wondered about with eating, for example vegetables or high fiber diet, it is examined specific molecules that have both a direct as well as an endocryne path that would circulate things back to the cardiac muscles, and having the muscles becoming more protective because of regulation of certain transcriptomic pathways to support cardiac muscle contraction. So we were very impressed by both the new concept as well as the state of the art technologies employed in this investigation.
Dr. Francine Marques: Thank you, that's very nice.
Dr. Carolyn Lam: I couldn't agree more, you put it so beautifully Peipei. I thought that it was really nice also linking pathways as well as linking several organ systems. Is there anything you might want to highlight about the renal effects, not just cardiac?
Dr. Francine Marques: Yes. Many times investigations been focusing on if something went wrong how do we cure it? More precious is when we find novel results telling us the healthy individuals, what are the things we should be doing so our blood pressure would stay at the normal level, or our cardiac function is being protected if there's an insult or injury. And so in this situation, the examination of the entire renal transcriptomic do give us very valuable information on how the blood pressure regulation system that maybe actually protected by the short chain fatty acid acetate.
Dr. Carolyn Lam: So true Francine. Anything else to add?
Dr. Francine Marques: Just to say circulation, for giving the opportunity to submit this paper, and share it with the world. We're very very excited about the data.
Dr. Carolyn Lam: Yeah we should be the ones to thank you. It's a beautiful paper. We're very privileged to publish it in circulation. May I ask what are next steps for you? What do you think needs to be done from here?
Dr. Francine Marques: We're validating this in other models now. And we're also looking into the [inaudible 00:13:57] microbiome and how that's related to habitation. So trying to really pinpoint mechanisms and how we can move this forward into the clinic.
Dr. Carolyn Lam: That's so great. And Peipei, do you think that there's certain gaps that urgently need to be addressed now?
Dr. Peipei Ping: Yes, I think one of the most beautiful thing that ... Concept, illustrated this investigation is we really couldn't be just focusing on one organ, our primary interest organ, heart, alone. What's demonstrated here is a beautiful link of both mechanism as well as governed by transforming parbolytes with endocryne effects. How the gut, the kidney, and the heart are all connected together in this process, achieving a better protective condition in the environment for the cardiac muscle.
Dr. Carolyn Lam: Thank you listeners. You've been listening to Circulation on the Run. Tune in next week for even more news.
Dr. Carolyn L.: 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. On our podcast today we are discussing the role of diastolic stress testing and the evaluation of heart failure with preserved dejection fraction, a really hot topic indeed, but first here's your summary of this week's issue.
The first study tackles the obesity paradox in cardiac surgery, where morbidity and mortality are lower in obese patients. This study sought to ask the question, "Is this due to reverse epidemiology, bias, or confounding?" To answer this question, Dr. Maris Kelko and colleagues from University Leicester in United Kingdom used two separate analysis. One, registry data from the National Adult Cardiac Surgery Registry and two, a systematic review in meta-analysis of studies. Of more than 400,000 patients in the cohort study and more than 550,000 patients in the systematic review, the authors found a U shape association between mortality and body mass index classes, where lower mortality was observed in overweight and obese class one and two patients, relative to normal weight patients, and mortality was increased in underweight individuals.
Now, the obesity paradox has been attributed to reverse epidemiology where the survival benefit associated with obesity is thought to actually reflect worse outcomes in the underweight patients who also had frailty, cachexia, or severe chronic disease. However, in the current study, counter to the reverse epidemiology hypothesis, the protective effects of obesity were less in patients with chronic renal, lung, or cardiac disease and greater in older patients as well as in those with complications of obesity, such as metabolic syndrome and atherosclerosis. Furthermore, adjustments for important confounders did not alter the results. The authors therefore concluded that obesity is associated with lower risks after cardiac surgery with consistent effects noted in multiple analysis even after attempting to address residual confounding and reverse causation.
The authors even went as far as to suggest that their findings do not support common practice where weight loss is recommended prior to surgery or where very obese patients are refused surgery in the morbidly obese. These provocative findings are discussed in an accompanying editorial by Doctor's Carnethon and Kahn from Northwestern University. While the editorialists agree that this well-designed study highlights an important knowledge gap, they pointed out that the obese class two patients had nearly five times greater risk for deep sternal wound infection and 25% higher likelihood of needing renal replacement therapy.
In such patients additional intervention in the perioperative period may still be indicated and include weight loss recommendations and postoperative surveillance for complications. Thus, a more cautious final recommendation may be for future studies to prospectively assess weight loss interventions prior to elective surgery in the context of overall surgical risk as assessed by the EuroSCORE or STS models.
The next paper describes mechanistic studies showing for the first time that nucleoside diphosphate kinase suppresses cyclic-AMP formation in human heart failure. In this paper by First Authors, Dr. Abu Taha and Hagemann, corresponding authors Dr.'s Tobref and Weilend from the Heidelberg University in Germany, the authors performed biochemical studies of nucleoside diphosphate kinase and G Protein signaling in human and rat tissue samples, assessed the functional impact of nucleoside diphosphate kinase C on cyclic-AMP levels and contractility and isolated red cardiomyocytes and determined that in vitro effects of these nucleoside diphosphate kinases on contractility in zebra, fish and mice.
They identified nucleoside diphosphate kinase as the critical isoform for the regulation of G Protein function and cyclic-AMP levels in the heart with important consequences for cardiac contractility. The increased nucleoside diphosphate kinase membrane content in human heart failure could potentially counteract a fading beta adrenoceptor response in the early stages of heart failure by increasing the amount of G Alpha stimulatory proteins in the plasma membrane. However, by switching from stimulatory to G Alpha inhibitory to activation, nucleoside diphosphate kinase may play a role in heart failure progression by reducing cyclic-AMP levels, typical for end-stage human heart failure.
The study, therefore contributes to a better understanding of the molecular processes, underlying alter G Protein signaling in heart failure, and may help to develop new heart failure therapies.
The next study tested the hypothesis, that high intensity interval training is superior to moderate continuous training in reversing cardiac remodeling and increasing aerobic capacity in patients with heart failure and reduced ejection fraction.
Doctor Ellingson and colleagues from the Norwegian University of Science and Technology, performed a multicenter trial, comparing twelve weeks of supervised interventions of high-intensity interval training at 90 to 95% maximal heart rate, moderate continuous training at 60 to 70% maximal heart rate, or a recommendation of regular exercise in 261 patients with heart failure and ejection fraction less than 35%, in New York Heart Association class II or III status.
The primary end point of change in left ventricular end-diastolic diameter from baseline to twelve weeks was not different between the high-intensity and moderate continuous groups. There was also no difference between the high-intensity and moderate groups in peak oxygen uptake, although both were superior to the recommendation for regular exercise. None of these changes were maintained at follow up after 52 weeks. Serious adverse events were not statistically different. However, training records showed that 51% of patients exercised below the prescribed target, during supervised high-intensity interval training, and 80% above the recommended target in those with moderate continuous training. Given that high-intensity interval training was not superior to moderate continuous training, in reversing remodeling or improving secondary end points, and considering that adherence to the prescribed exercise intensity based on heart rate was difficult to achieve even in the supervised setting.
The authors concluded that moderate continuous training remains the standard exercise modality for patients with chronic heart failure.
The final paper tells us, that brain emboli after left ventricular endocardial ablation may be more common than we knew. First author Doctor Whitman, corresponding author Doctor Marcus and colleagues from University of California studied eighteen consecutive patients, scheduled for ventricular tachycardia or premature ventricular contraction ablation, over a nine month period. Twelve patients undergoing left ventricular ablation were compared to a control group of six patients, undergoing right ventricular ablation only. Heparin was administrated with a goal activated clotting time of 300 to 400 seconds for all left ventricular procedures. Pre impulse procedural brain magnetic resonance imaging was performed on each patient within a week of the ablation procedure. The authors found that seven of the twelve patients, or 58% undergoing left ventricular ablation, experienced a total of sixteen cerebral emboli, compared with none among patients undergoing right ventricular ablation. Seven of the eleven patients undergoing a retrograde approach to the left ventricle, developed at least one new brain lesion. Thus, more than half of patients undergoing routine left ventricular ablation procedures, experienced new brain emboli after the procedure, even in the absence of clinically apparent stroke.
Future research is critical to understanding the long-term consequences of these lesions and to determine optimal strategies to avoid them. This is further discussed in an editorial entitled "The Sound of Silence". How much noise should we make about post ablation silence strokes? By Doctor Z and Vora from Stanford University. Well, those were your summaries, now for our featured discussion.
I am so thrilled to have with me two special guests to discuss the topic of the diagnosis of heart failure preserved ejection fraction or HFpEF. As you all know, that's my favorite topic and I have favorite people with me today. First, the corresponding author of our feature paper, Doctor Barry Borlaug from Mayo Clinic, Rochester, Minnesota. And, for the first time on the podcast, Doctor Mark Drazner, Senior Associate Editor from UT Southwestern. So, welcome Barry and Mark.
Barry Borlaug: Thank you Carolyn.
Mark Drazner: Thank you, great to be here.
Dr. Carolyn L.: So, Barry, you talked about the role of stress diastolic testing, shall I call it, in the diagnosis of HFpEF in your paper. Could you tell us why you looked at it and what you found?
Barry Borlaug: Sure, Carolyn. When you have dyspnea and fatigue and you got a low EF, it's pretty easy to make the diagnosis of heart failure reduced EF, but we've been struggling for years with making the diagnosis of dyspnea, whether it's HFpEF or not in people with normal ejection fraction. And that's because physical and laboratory and clinical signs of high filling pressures and congestion, are either difficult to see or only present during stress, like physical exercise, in patients. So that's really what motivated us to pursue this study.
We took patients, that were referred to our cath lab for invasive hemodynamic exercise testing, so we directly measured filling pressures, PA pressures and cardiac output reserve, to get a gold standard assessment, whether people have heart failure or not. And then we performed simultaneous echocardiography and blood testing to measure NT-proBNP levels, and then we just looked at what we could figure out. Can you accurately discern HFpEF patients from patients without cardiac dyspnea, using these non invasive estimates.
We saw that a lot of people, with, for example, NT-proBNP levels that are low enough to be where most would consider HFpEF excluded, actually had HFpEF. And we saw that there were modest correlations between non-invasive echocardiographic estimates of filling pressures, specifically the E to E Prime ratio, and directly measured left heart filling pressures. But when we applied the criteria that had been initially proposed, we saw poor sensitivity to make the diagnosis with exercise. And this was largely related to the difficulty with getting all of the different echocardiographic indices, that are currently examined as part of the diastolic stress testing non-invasively. Next, we looked at just adding the exercise E to E Prime, which is an estimate of filling pressures, and when we used the cut-point, that's already been proposed, according to contemporary data, we found that this substantially improved the sensitivity to identify HFpEF, but there was a bit of a trade-off in that specificity decrease.
Dr. Carolyn L.: That's so cool. So let me summarize some of these take-home messages here. First of all, using just rest echo. I was really impressed to see that rest echo indices alone only identifies a third to maybe up to 60% of the patients you found with invasively proven HFpEF. So, we may be specific, but we're really missing quite a number of patients. And then if you exercise them, what your data is really showing is that it's better to exercise them and use this data for the negative predictive value, isn't that what you're saying?
Barry Borlaug: You know, the exercise is really the gold standard, so it gives you both, the negative and positive. With the echocardiography, relying on the exercise E to E Prime ratio, that was really helping us, as you say, Carolyn, with the higher negative predictive value. So most people, that had HFpEF, in this series, where we could get adequate, highly controlled environments, adequate diagnostic echocardiographic data, most people that ended up having HFpEF fit those criteria, we could see an elevation in this E to E Prime on exercise, so it did provide good negative predictive value.
Dr. Carolyn L.: These are just such important data, because I think we're all still struggling with how to make this diagnosis of HFpEF. Mark, could you just share some thoughts on whether you think this is going to really change practice, even change guidelines?
Mark Drazner: I think, if you read this paper, you would recognize it, that it's certainly a critical question that we're all facing, how to make the diagnosis of HFpEF. And all of their guidelines that have been advocated, there really wasn't much data, and these really are the best data out there. So, certainly, it's [inaudible 00:15:41] me a direction of changing practices. Barry says, certainly, the approach will need to be validated, I think, before it reaches high level guidelines, but certainly I think it's a step in the right direction, and points the way towards the future in terms of improving our ability to diagnose HFpEF. And really, that's why both reviewers and [inaudible 00:15:59] this is such an important paper.
Dr. Carolyn L.: Right. Barry, I have a quick question for you though. Doing exercise echo, not easy. E to E Primes are all over the place usually. How easy was it? How feasible was this test?
Barry Borlaug: So, first I'd like to say that we have outstanding, very well-trained, very highly skilled research scenographers, here at Mayo doing this. In very controlled environment, we're providing plenty of time for them to obtain images and that's going to be a question moving forward, because not everybody in clinical practice has that capability. But with that said, in this very controlled environments, skilled scenographers, we were able to measure the exercise data during low level exercise about 85 to 90% of the time and at peak exercise about 75 to 80% of the time. So, it's fairly feasible, but even in this best case scenario, we can't get it on everybody.
Mark Drazner: Even in the [inaudible 00:19:49] echo lab, the recommended approach by the ASE with the four measures. How many times they were not able to acquire all those images, are necessary for those four techniques and so, here you have a [inaudible 00:20:03] of AS echo lab not being able to do that, and being transparent about that, and [inaudible 00:20:08] to the community, saying that, although these are ideal measures, even the [inaudible 00:20:12] perhaps you can't acquire them. I think that was another important point that came out of this and then lead to the focus on the E to E Prime.
Barry Borlaug: I couldn't agree more. You got one of the world renowned labs, very skilled scenographers doing imaging, and we're still not able to get it all in each patient, and that just points to the difficulty of getting really high quality diagnostic images, and a lot of time you need the next level test, when that happens. And invasive exercise testing is really that test, the gold standard.
Mark Drazner: When you get echos from the outside and you look at the E to E Primes, are you confident that the data, that's generally acquired, is gonna be acceptable for this [inaudible 00:20:50]?
Barry Borlaug: Yes and no, I mean I'm always a little bit concerned, but it's not just being a control freak, you know, wanting to see everything, but I think that if it's a still frame doppler, tissue doppler spectrum, you can see that the sample volume is in the right place, and it's really unequivocally normal or abnormal, I feel pretty good about that. Not as good as when they get a full dedicated study here.
Mark Drazner: Of course, the gold standard is also difficult. The invasive measurement.
Barry Borlaug: Yes it is, I didn't [inaudible 00:21:18] that, but we've been doing a lot of invasive exercise tests for the last ten years now. And we do like 250 a year here, so we're really quite [inaudible 00:21:28] but we have all hands on deck in the lab. We have a couple technicians running gas samples around, all over the place. Somebody is on the medgraphics card, measuring oxygen consumption. We've got a nurse in there, that's helping out, so it's complicated, and of course we're using the micromanometer catheters for the pressure assessments, because you get so much more artifacts from width and under damping and over damping with the pressure tracing, so that's also not easy to do if you say.
Mark Drazner: So maybe for practicing cardiologists it's gonna be hard to duplicate that and perhaps spend the energy in terms of doing the exercise echo techniques off the speed, for example. Perhaps, it's another message.
Barry Borlaug: I would agree completely. And I think that again, when you do that, if you do a really high quality exercise echo and it's still not quite definitive, then you can refer on to a center that does have that capability, because obviously it's just reality, not everybody is going to be able to do this. Not every place has the size and resources to be able to do these really advanced tasks.
Dr. Carolyn L.: And do you apply exercise echo now in making your diagnosis? How do you use this data, for yourself, clinically?
Barry Borlaug: We started to think about this, and I think that the best case scenario where the people, that really have an intermediate pretest probability, based on their clinical characteristics. Somebody has jugular distension and a very high NT-proBNP level, and edema, you really don't need further testing, you know that that's going to be HFpEF. And if somebody has no risk factors, and everything is stone cold normal, they don't.
But in some of these people that have some signals, but they don't quite meet criteria, we are doing this, again, if they have adequate echocardiographic images at rest. And then we're looking really carefully at the exercise echocardiography data, one concern from this data, I want to make sure people are very circumspect and really critically looking at the quality of their data, because we shouldn't over-interpret equivocal findings. And as you said earlier, E to E Primes can be all over the map, they're very difficult to obtain during exercise. But I think that if everything looks very high quality and is definitely abnormal or definitely normal, that can be helpful. More so, if it's normal. We did see more false positive, so if it is abnormal, we did suggest that you may want to perform further confirmatory testing, because of the higher false positive rate with exercise echo.
I would say for the listeners, they should take a look at his figure six, which really is a nice diagnostic algorithm, where Barry shows, or advocates, for taking patients with intermediate probability and then using this to restratify that, using [inaudible 00:19:40] approach. I know that, that figure resonated with the editors and the reviewers dramatically, so I'd encourage listeners to take a look at that.
Dr. Carolyn L.: Listeners, you heard it right. [inaudible 00:22:36] Circulation on the Run. Don't forget to tell all your friends about this podcast and tune in next week.
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 am so excited to be discussing the diabetic HFpEF or heart failure with a preserved ejection fraction phenotype, with world experts and new insights from the I-PRESERVE Trial. That will just be in a moment and here are your summaries first.
The first paper in this issue is a systematic review and meta-analysis of risk factors for Co-Arctation of the Aorta on pre-natal ultrasound. In this paper by first author Dr. Familiari and corresponding author Dr. D'Antonio and colleagues from Arctic University of Norway, the authors performed a systematic review of 12 studies on 922 fetuses with echo-cardiography, and found that those with a post-natal diagnosis of co arctation had significant differences in several cardiac morphological parameters compared to cases without co arctation. The presence of a co arctation shelf, or hypoplastic arch, was associated with a significantly increased risk of co arctation. Furthermore, they reported multi-parametric diagnostic models that were associated with an increased detection rate. Thus, this paper tells us that assessment of left inflow and outflow tracts prenatally may help in stratifying the risk of co arctation.
The next paper reports pre-clinical data that truly represents a paradigm shift in our understanding of vascular resident endothelial progenitors in tissue regeneration. In this paper by first author Dr. Patel, corresponding author Dr. [Cossroterrani 00:02:00], and authors from Royal Brisbane and Women's Hospital in Australia, the authors studied protein expression levels of common endothelial markers in mice using flow cytometry. They discovered an endovascular progenitor cell in vivo that is present in normal endothelium in the aorta and lungs and activated in vessel walls during various endogenic situations, such as in the placenta, skin wound healing, and tumors. They further define at a molecular level an entirely novel endothelial hierarchy from an endovascular progenitor cell to a mature different-shaded endothelial cell via complete RNA sequencing. They further clarify the linage of endothelial progenitors in their origin by using bone marrow transplantation and vascular-specific, lineage-tracing mouse models, showing that the endovascular progenitor cells were derived neither from bone marrow nor from hematopoietic progenitors. This discovery of an endovascular progenitor cell will have significant implications for the development of endothelial progenitors as a cell therapy.
The next paper addresses the chicken or egg question regarding the association between obesity and atrial fibrillation, and this is done using Mendelian randomization to define a causal association between body mass index and atrial fibrillation. In this study by Dr. Chatterjee and colleagues from Massachusetts General Hospital, the authors looked at more than 50,000 European individuals without atrial fibrillation at baseline and showed that genetic variance associated with increasing body mass index were significantly associated with an increased risk of atrial fibrillation. The association between genetically determined obesity and atrial fibrillation persisted even after adjustment for traditional atrial fibrillation risk factors, such as hypertension, diabetes, coronary artery disease, and heart failure. Taken together, these data are consistent with a causal association between increasing body mass index and incident atrial fibrillation. These findings therefore support the primordial prevention of obesity as a significant public health target to combat the expanding global burden of atrial fibrillation.
The last paper provides contemporary estimates of the stroke burden in China, a country which bears the biggest stroke burden in the world. In this paper by doctors Wang and Fagen from the Capital Medical University in Beijing, China and Auckland University of Technology in New Zealand, and colleagues, the authors reported results of a nationally represented door-to-door survey conducted in 2013 in 155 urban and rural centers in 31 provinces in China, totaling 480,687 adults. They found that the age standardized prevalence was 1,115 per 100,000 people, incidence rate was 247 per 100,000 person years, and mortality rates were 115 per 100,000 person years. The stroke prevalence estimates in 2013 were greater than those reported in China three decades ago, especially among the rural residents. Finally there was a north to south gradient of stroke in China, with the greatest burden observed in the northern and central regions. Well, that wraps it up for our summaries. Now for our discussion.
For our featured discussion today, we are talking about my favorite topic and of course that is HFpEF, or heart failure with preserved ejection fraction, and I am so thrilled to have with us today Dr. John McMurray from University of Glasgow, who's the corresponding author of our featured paper referring to diabetes in patients with HFpEF and really talking about the novel results from the I-PRESERVE Trial. Welcome, John!
John McMurray: Thank you Carolyn, it's always a pleasure to speak to you.
Carolyn Lam: Oh, I have been waiting for this one, and I'm so excited I don't know where to begin, but how about with this? Diabetes and HFpEF, first of all, haven't we spoken to death about co-morbidities in HFpEF? And secondly, what makes this paper special? Because we've heard about diabetes and HFpEF from CHARM, from DIG, from Relax, so tell us: why the interest in diabetes and HFpEF?
John McMurray: Sure, Carolyn. I think you and I have been interested in diabetes and heart failure, that terrible combination, for a long time. But I think there's a lot more interest in it today because, of course, we've had several new clinical trials with interventions to lower blood glucose that have showed both beneficial and potentially harmful effects on the development of heart failure. But really what these trials have highlighted is just how common heart failure is as a complication of diabetes. And we strongly suspect, though we don't know for sure of course, but we strongly suspect that most of that heart failure developing amongst patients with diabetes is probably heart failure with preserved ejection fractions. So, I think the context currently is that what's different about our study compared to the ones that you mentioned is that in I-PRESERVE we measured a number of things that were not available in, particularly, the large clinical trials previously. So, in I-PRESERVE we measured natriuretic peptides, we looked at health-related quality of life, and maybe most importantly of all we had a large echo-cardiographic sub study. So I-PRESERVE is quite different than DIG-Preserved and CHARM-Preserved, and of course a lot larger than the RELAX HFpEF study.
Carolyn Lam: I was the associate editor managing your paper and I was so excited about this that I invited an editorial as well by Brian Lindman, and he's got this beautiful table that summarizes what your study really adds to the literature, and I think it's so critical. Could you start by summarizing? What are the main findings?
John McMurray: Well, I-PRESERVE, as you know, was a trial of just over 4,000 individuals with HFpEF defined clinically and with an ejection fraction of 45% or above. There was actually a trial comparing the angiotensin receptor-blocker [inaudible 00:09:17] placebo, though in fact there is no difference in morbidity and mortality between those two treatment groups. So we've looked, as you said, at the patients who had diabetes and compared those to the patients who didn't have diabetes. I think there was some very interesting novel information; if you look at the two subsets of patients, they actually don't differ in terms of age and sex and, importantly, in left ventricular ejection fraction.
But there are other differences that you would expect; for example, many more of the patients with diabetes were obese. But interestingly, and despite that, the patients with diabetes had higher, significantly higher, NT-proBNP levels. So as you know, obesity tends to be associated with lower rather than higher natriuretic peptide levels, so here we were finding higher natriuretic peptide levels in a subset of patients who were actually, by and large, more obese. And there was no difference in other things that might have accounted for that difference; natriuretic peptides, for example, there was no difference in the proportion of patients who had atrial fibrillation.
So that was important, and that's also important when we come to think of outcomes because of course the previous studies reporting worse outcomes in patients with diabetes had not adjusted for natriuretic peptides because they by and large weren't available in the large prior trials. So that, of course, could have accounted for some of the worse outcome.
Some of the other things, features, maybe to pick out in terms of baseline characteristics ... one was that these patients had many more features of congestion, so patients with diabetes had more edema, more often had a raised jugular venous pressure and so on, and that's interesting given some of the recent clinical trial data that we might come back to. And even though the [inaudible 00:11:22] class distribution was not different between patients with diabetes and those without, what was very different was health-related quality of life, which was much worse in patients with diabetes than those without. Now you could if you chose to, Carolyn, look at that as saying that physicians weren't assessing worse functional status or symptomatic status in the patients with diabetes, but the patients were certainly self-reporting a much worse health-related quality of life.
So those were the, sort of, clinical characteristic differences. We did, as I said, have an echo-cardiographic sub study. There were 745 patients in total in the trial who had a detailed echo study, and there were perhaps more modest differences than I might have expected (and I'd be interested in your opinion about this) in patients with diabetes. So they had a somewhat greater, statistically significantly greater left ventricular mass, they had increased early diastolic mitral inflow velocity through E, they certainly had increased E over E prime increased left atrial areas, so there was some left ventricular remodeling and there was some evidence of increased left ventricular filling pressure, maybe diastolic disfunction. But the differences were not very striking; they were there, and as I said previously, ejection fraction (which most of us regard as perhaps not a very good measure of systolic function) was similar between the two groups. We didn't look at more sophisticated and [inaudible 00:13:09] measures of systolic functions so those could have been different, we just don't know.
So that's the baseline clinical features and baseline echo-cardiographic findings. And then, of course, we followed these patients for a median of just over four years and what we found was that the cardiovascular and all cause mortality was about twice as high in patients with diabetes as in those without. And if you adjust for conventional clinical variables, including NT-proBNP, which is individually the most powerful predictor of outcome, you only very slightly attenuate that greater risk associated with diabetes. The risk of heart failure and hospitalization was also about doubled in an unadjusted analysis, but that was more attenuated in the adjusted analysis. But you've also got to remember that, of course, the patients with diabetes were not surviving as long, so the very fact that they had a substantially higher risk of heart failure and hospitalization despite a shortened longevity is important.
Then lastly, again I think a fairly unique aspect of this study was that we then added the echo-cardiographic findings into the multi-variable model [inaudible 00:14:33] because it was only a subset of patients in which we had echo-cardiographic measurements. The statistical reliability of this is not as robust as in the main model, but what we saw was that there was more attenuation of the risk associated with diabetes when you added in the remodeling and diastolic dysfunction findings that we saw in the echo-cardiographic sub study. So that's a summary, I think, of the key points.
Carolyn Lam: John, I was really impressed and struck by the consistency of the message, which is what I really appreciated. What you added to the field was this consistent message that the diabetic HFpEF just had more signs of fluid overload in general, be it clinical, be it by NT-proBNP, be it by echo. And I thought that was something you said it was a moderate difference by echo; it was enough to be convincing to me, and I really appreciated that. The fact that adding the echo findings attenuated the significance ... you know we went back and forth about that quite a bit together, didn't we?
John McMurray: We did.
Carolyn Lam: I think at the end it is consistent, it is useful information. It tells me that perhaps some of these outcomes are mediated by this access fluid, to me, at least part of it. And I think that is how we ended up expressing it in the final paper.
John McMurray: I think you are absolutely spot on, Carolyn, because I don't think I had anticipated that the features of congestion would be so different. And you are correct in that, of course, correlates very well with natriuretic peptides, with the left atrial enlargement and so on.
And then of course (and this is clearly extrapolation) but then of course it makes one wonder about some of the trials with diabetes drugs that we've seen. The TZDs, glycosomes, which calls a little bit of fluid retention, of course precipitating heart failure, and then the opposite recently with the SGLT2 inhibitors which of course are diuretics, and those drugs preventing the development of heart failure.
And it does make me wonder if the diabetic phenotype maybe was a little bit of renal dysfunction, some subtle renal dysfunction, is a sodium and water avid phenotype state and that it doesn't take very much to tip those patients into frank heart failure and perhaps we need to think (and I think you might have been alluding to it) think about insuring that we adequately diurese these patients given that in this study where people were supposed to be optimally treated, clearly there was still a lot of evidence of residual fluid overload.
Carolyn Lam: I absolutely agree, and yes you read my mind that I was going to allude to the implications for therapies that have a diuretic effect, you know, like the SGLP2 inhibitors and in fact this was discussed in Brian Lindman's editorial, which is a must read.
Just another question though. What do you think of peripheral mechanisms contributing to all this?
John McMurray: Yeah, obviously there is the kidney aspect that we saw a relatively small difference in estimated GFR. Of course that only tells you one aspect of renal function and the nephron in diabetes may well be sodium avid maybe more likely to retain water. So certainly the kidney as a peripheral mechanism might be very important.
And then of course the blood vessels, I mean there's no question that patients with diabetes have more abnormal endothelial function probably have got enhanced vascular stiffness. And of course we know from a long time ago at least in HFrEF (I'm not so sure about HFpEF) but in HFrEF there's evidence that some of the vascular stiffness you see in patients with HFrEF is actually due to sodium in the vessel wall and there's some beautiful old-style clinical physiology experiments showing that if you diurese patients with HFrEF you restore vasodilation you restore basal motor responsiveness. It could also be true in HFpEF though of course patients with HFpEF and many other reasons to have vascular stiffness.
So yes, peripheral mechanisms may well be important. Your humoral abnormalities may be more pronounced in patients with HFpEF and diabetes compared to those without diabetes. We don't know because I'm not sure that's been measured very often. Certainly natriuretic peptides are, but what about things like the angiotensin system and arginine/vasopressin and the sympathetic nervous system. You know, there's still so much to study looking at patients with heart failure with and without diabetes because they're really quite distinct. And whatever's going on it makes a big difference the way those patients feel, what they can do, and what happens to them.
Carolyn Lam: Yeah, and your study really establishes that. Congratulations once again John, it's just been such a delight chatting with you.
John McMurray: Likewise, Carolyn.
Carolyn Lam: Listeners, you heard it right here on Circulation on the Run. Don't forget to tell all your friends about this podcast and turn in next week!
Dr. 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 podcast is taking us to Japan today where we will be talking about aspirin for primary prevention in patients with diabetes. First, here's your summary of this week's issue.
The first study provides insight into the development of neurologic injury in patients with single ventricles undergoing staged surgical reconstruction. In this paper by Dr. Fogel and colleagues from the Children's Hospital of Philadelphia, the authors recognize that single ventricle patients experience greater survival with staged surgical procedures culminating in the Fontan operation, but experience high rates of brain injury and adverse neurodevelopmental outcome. They therefore studied 168 single ventricle patients with MRI scans immediately prior to bi-directional Glenn, prior to the Fontan, and then three to nine months after the Fontan reconstruction. They found that significant brain abnormalities were frequently present in these patients and that the detection of these lesions increased as children progressed through staged surgical reconstruction. In addition, there was an inverse association of various indices of cerebral blood flow with these brain lesions. This study therefore suggests that measurement of cerebral blood flow and identification of brain abnormalities may enhance recognition of single ventricle patients at risk for poor outcomes, and possibly facilitate early intervention.
The next paper uncovers a unique mechanism underlying arrhythmogenesis and suggests that the anti-epileptic drug valproic acid may possibly be repurposed for anti-arrhythmic applications. In this paper by first authors Dr. Chowdhury and Liu and corresponding author Dr. Wang and colleagues from University of Manchester UK. The authors used mouse models and human induced pluripotent stem cells derived cardiomyocytes to discover a new mechanism linking mitogen activated kinase-kinase 7 deficiency with increased arrhythmia vulnerability in pathologically remodeled hearts. Mechanistically, mitogen activated kinase-kinase-7 deficiency in the hypertrophied hearts left histone deacetylase-2 unphosphorylated, and filamin A accumulated in the nucleus, which then formed an association with kruppel-like factor 4 preventing its transcriptional regulation. Diminished potassium channel reserve caused repolarization delays resulting in ventricular arrhythmias, and the histone deacetylase-2 inhibitor, valproic acid restored potassium channel expression abolishing the ventricular arrhythmias. This study therefore provides exciting insights in developing a new class of anti-arrhythmics specifically targeting signal transduction cascades to replenish repolarization reserve, all for the treatment of ventricular arrhythmias.
Does the Mediterranean diet improve HDL function in high risk individuals? Well, the next paper by first author Dr. Hernaiz, corresponding author Dr. Fito and colleagues from Hospital Del Mar Medical Research Institute in Barcelona, Spain addresses this questions. The authors looked at a large sample of 296 volunteers from the PREDIMED study and compared the effects of two traditional Mediterranean diets, one enriched with virgin olive oil, and the other with nuts to a low-fat control diet. They looked at the effects of these diets on the role of HDL particles on reverse cholesterol transport, HDL antioxidant properties, and HDL vasodilatory capacity after one year of dietary intervention. They found that both Mediterranean diets increased cholesterol efflux capacity and improved HDL oxidative status relative to the baseline. In particular, the Mediterranean diet enriched with virgin olive oil decreased cholesterol ester transfer protein activity, and increased HDL ability to esterify cholesterol, paraoxonase-1, arylesterase activity, and HDL vasodilatory capacity. They therefore concluded that adherence to a traditional Mediterranean diet, particularly when enriched with virgin olive oil, improves HDL function in humans.
The final study tells us that among hospitalized medically ill patients, extended duration Betrixaban reduces the risk of stroke compared to standard dose enoxaparin. In this retrospective sub-study of the APEX trial, Dr. Gibson and colleagues from Beth Israel Deaconess Medical Center and Harvard Medical School in Boston, Massachusetts randomized 7,513 hospitalized acutely ill patients in a double-dummy, double-blind fashion to either extended duration of the oral Factor Xa inhibitor Betrixaban at 80 mg once daily for 35 to 42 days, or standard dose subcutaneous enoxaparin at 40 mg once daily for 10 days all for venous thromboprophylaxis. They found that the extended duration Betrixaban compared with enoxaparin reduced all cause stroke by almost one half with a relative risk of 0.56 equivalent to an absolute risk reduction of 0.43 percent and number needed to treat of 232. The effect of Betrixaban on stroke was explained by a reduction in ischemic stroke with no difference in hemorrhagic stroke. The reduction in ischemic stroke was confined to patients hospitalized with acute heart failure or non-cardioembolic ischemic stroke.
This paper is accompanied by an editorial by Drs. Quinlan, Eikelboom, and Hart in which they articulate three reasons that they think these results are important. First, the results demonstrated an unexpectedly high rate of new or recurrent ischemic stroke during the first three months in hospitalized medical patients receiving standard enoxaparin prophylaxis, the rate being even higher in patients presenting with heart failure or ischemic stroke. Secondly, the data demonstrated for the first time that a NOAC reduces the risk of ischemic strokes in patients without known atrial fibrillation. Thirdly, the effects of Betrixaban on stroke were dose dependent, all of the benefits were seen in those who received the 80 mg dose, whereas the 40 mg dose did not provide advantages compared with enoxaparin or placebo. While these results are encouraging, the editorialists also warn that these are based on a post-hoc analysis and should be considered hypothesis generating.
Well, that brings it to the end of our summaries. Now for our feature discussion.
Today our feature discussion focuses on the exciting 10-year follow up results of the Japanese Primary Prevention of Atherosclerosis with Aspirin for Diabetes, or JPAD trial. I am simply delighted to have with me first and corresponding author Dr. Yoshihiko Saito from Nara Medical University, Japan. As well as a familiar voice on this podcast, Dr. Shinya Goto associate editor of Circulation from Tokai University in Japan. Welcome gentlemen!
Dr. Goto: I am very pleased to have this opportunity. I am always enjoy listening your podcast, and this is very interesting topic of aspirin in prevention cardiovascular event in patients with diabetes, type II diabetes.
Dr. Lam: I couldn't agree more, because the burden of cardiovascular disease globally is actually shifting to Asia, and the burden of diabetes especially, is one of the fastest growing in Asia. So a very, highly relevant topic indeed. Could I start, Yoshi, by asking you: these are the 10 year follow up results, what inspired you to take a re-look at the original JPAD results and to report this 10 year result?
Dr. Saito: The American guidelines said that low-dose aspirin is recommended to the type II diabetes patient for the primary prevention of cardiovascular events who are older than 30 years old, and who are not contraindicated to aspirin. That meant that almost all type II diabetes patients were recommended to low dose aspirin. However, at that time there was no direct [inaudible 00:09:49] evidence for it. So we connected the prospective randomized control trial that examined the effects of the low dose aspirin on primary prevention of cardiovascular events in type II diabetes patients without preexisting cardiovascular disease. The name of this trial, JPAD trial, that stand for the Japanese Primary Prevention of Atherosclerosis with aspirin in Diabetes. We enrolled 2,539 patients who were assigned to the low dose asprin group or the no aspirin group. So we followed them with a median follow up period of 4.4 years.
The results of the original JPAD trial were that low dose aspirin reduced CV events by about 20%, but the reduction could not reach statistical significance. So I don't know the exact reason, but one is the reason is low statistical power, because event rate was about one-third of the anticipated. Another reason is that low dose aspirin really could not reduce cardiovascular events. So we decided the extension of the follow up of the JPAD trial to elucidate the efficacy and safety of long term therapy with low dose aspirin in type II diabetes patients. This extension study was named the JPAD 2 study. We followed them up to the median follow up period of more than 10 years.
In this time the JPAD trial study, we analyzed the patients in a pod protocol method because the randomized control trial was ended after 2008. Finally, we analyzed the 992 patients in the aspirin group, and 1,168 patients in the no aspirin group who retained the original allocations throughout the study period. The primary endpoint were composite endpoint of cardiovascular events including sudden cardiac death, the fatal and the non-fatal coronary artery disease, fatal and non-fatal stroke, peripheral vascular disease, and aortic dissection. This end point is the same as the original JPAD trial. The main results are the primary endpoints, 15.2% of patients occurred primary endpoints in aspirin group, and 14.2% in the no aspirin group occurred in the primary endpoints. So the primary endpoints rate is singular in both groups, with the hazard ratio is 1.14 with a 95% CI is 0.91 to 1.42 with a p value of 0.2 by log-rank test. So the low dose aspirin therapy could not reduce cardiovascular events in the type II diabetes mellitus.
We also analyzed these data by intention to treat analysis, the results is singular. Again, the low dose aspirin therapy could not reduce the cardiovascular event in type II diabetes mellitus. However, I was told the hemorrhagic events, total hemorrhagic events was singular in both groups, but gastrointestinal bleeding of about 2% in the aspirin group but only 0.9% in no aspirin group. That means our gastrointestinal bleeding is doubled in the aspirin group compared with no aspirin group. This is the main outcome of the JPAD and JPAD-2 trials.
Dr. Lam: Thank you so much Yoshi, and really congratulations on such a tremendous effort. I completely applaud the idea of looking at the 10 year follow up trying to address the issue of whether or not it was a lack of power that limited JPAD-1, but what you found really reinforced what you found in JPAD-1, which is low dose aspirin did not reduce cardiovascular events in the diabetic group. They're still huge numbers, I'm so impressed that 85% of the treatment assignment was retained. Then furthermore you even showed increased gastrointestinal bleeding with aspirin. So really remarkable results. Can I just ask, are you surprised by the results, and how do you reconcile it with what was found in the general population studies like the Physician Health Study, or the US Preventive Services Task Force, where they really seem to say that primary prevention aspirin works in the general population when your risk is a certain amount?
Dr. Saito: I think that we studied only the type II diabetes patients, so it is not clear that our results are applied to the general population, but our results is very much similar to the current European guidelines and American guidelines.
Dr. Lam: That's a very interesting point about diabetic versus non-diabetic population and the utility of low dose aspirin. Shinya, you brought this up before. What do you think?
Dr. Goto: For the primary prevention population cohort study, aspirin demonstrated 25% reduction of cardiovascular event. We are not recommending aspirin for primary prevention due to the balance of bleeding and cardiovascular protection, absolute risk. In Yoshi's paper, in patients with type II diabetes aspirin evened that [inaudible 00:16:13], and that is very important message he had shown in this long term outcome randomized trial.
Dr. Lam: Do you think that there are some pathophysiologic differences when you study a diabetic versus non-diabetic population?
Dr. Goto: Yes, that is a very important topic, and we have very nice review paper by Dr. Domenico and Fiorito. In patients with diabetes the platelet time over becomes relatively rapid as compared to general population. New platelets come to blood and COX-1 inhibition by aspirin cannot reach to enough level in diabetes patient. Still, this [inaudible 00:16:57] hypothesis, very interesting hypothesis.
Dr. Saito: I think so, I think so. That review that proposed the same concept, their higher dose of aspirin as possibly effective for diabetic patient.
Dr. Lam: That's interesting. Are you planning any future studies Yoshi?
Dr. Saito: Yeah, maybe two times study.
Dr. Goto: But anyway, the event rate is currently very low than the old [inaudible 00:17:28]. So the sample size should be huge. Huge sample size is needed for the primary prevention setting to analyze the effect of aspirin, so the number needed to treat in the primary prevention setting is more than 1000. If diabetes patient, aspirin is resistant to aspirin so the number needed to treat is getting larger. So the sample size is getting larger and larger. That is not practical to perform that clinical trial.
Dr. Lam: That's a very good point that the contemporary trials like yours are really challenged by the low event rates because of improved preventive treatment across the board like high dose statins, like very, very low LDL targets, and so on. That's a good point. Actually, could I ask both of you gentlemen, and maybe Shinya you can start, can you let us know what is it like to perform such a large rigorous clinical trial in Japan? It must be a lot of effort. Could you give us an idea?
Dr. Goto: In Japan, medical care system is a little bit different from the U.S. Every patient covered by the homogeneous health care system so it means it is rather difficult to conduct a clinical trial. I appreciate the effort by Professor Saito, Yoshi, it is extremely difficult to conduct the study. Japan is relatively small island, patient stick to the clinic so the long term follow up with relatively low follow up can be expected. [inaudible 00:19:15] number of patients is a challenge, and Yoshi did succeed it. We can do that and due to the baseline therapy is quite homogenous, impact of the clinical care like this has very strong impact.
Dr. Lam: Exactly, and I share your congratulations once again to Yoshi for really tremendous effort, important results. Thank you so much Shinya for helping with this paper, and for really highlighting how really important it is. Did anyone have anything else to add?
Dr. Saito: Yes, I have one thinking, in respect to the Japanese clinical trials. I think the Japanese evidence, as derived from Japanese clinical studies is getting better and better in quality. Almost all Japanese clinical trials enrolled only Japanese patients, so the way the Japanese not so good at to organize the international clinical trial because of the, one is the language problem, and the other is funding problem. In Japanese funding agency, the AMED, that is similar to the NIH in United States, but AMED is not so strong as NIH so that they cannot give a bigger budget to the Japanese clinicians. That is another problem to organize a big clinical trial. The funding [inaudible 00:20:49] apprenticeship without holding investigators are very, very important to be better clinical situation in Japan, I think so.
Dr. Lam: Thank you for listening to Circulation on the Run, don't forget to tune in 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 Centre and Duke-National University of Singapore.
Today is special, special, special because here with me is the editor of special populations and that is Dr. Sharon Reimold from UT Southwestern, who is the editor handling the special issue for Go Red For Women.
Dr Sharon Reimold: Thank you, Carolyn. I'm happy to be here.
Dr Carolyn Lam: This is so cool. Just us ladies chatting about issues that we need to be talking about.
Now first of all, this is the first time that Circulation is doing a focus issue for Go Red for Women. Could you tell us a little bit more about that?
Dr Sharon Reimold: Sure. The Go Red for Issue campaign has been around for many years. The editorial staff realized that we really hadn't had an entire issue devoted to cardiovascular issues in women. We decided several months ago to try to make this a reality and asked for submissions of articles and we’re delighted to see the interest that our cardiologists across the country had, as well as across the world, in submitting their research for consideration in this issue.
Dr Carolyn Lam: I know. There are seven original papers. There are review papers. There are research letters. It's an amazing issue.
Dr Sharon Reimold: We had hoped to focus on a lot of different areas in which heart care in women is influenced. We're really quite delighted that we had papers on pregnancy, papers related to strategies to get women involved in trials. We were able to look at novel risk factors in women, and also, have an excellent review about arrhythmias in women versus men that I think everyone will want to take in.
Dr Carolyn Lam: Yeah. Congratulations once again right off, but let's jump straight into this set of twin papers that deal with post MI outcomes and sex differences. There've been quite a number of publications on this. What makes these two papers special?
Dr Sharon Reimold: I think these papers are special because they're trying to think more deeply into why women tend to get re-hospitalized after a heart attack more often and what are the reasons that they're getting readmitted.
For instance, it seems that women, as we know, may get a variety of different symptoms that are their equivalent or anginal equivalent after they've been in the hospital and also before they were in the hospital. I, personally, suspect that when somebody comes to the hospital with chest discomfort and they've recently had a heart attack, then often times, they get readmitted and re-hospitalized.
These papers are starting to look at mechanisms, why this happens. I think this will be the bridge to the point where we figure out what can we about this, to hopefully, make men and women more equal in this regard.
Dr Carolyn Lam: That's so true and well put. I also found very, very interesting and important that paper that really highlighted the importance of coronary flow reserve and microvascular ischemia, not just obstructive disease. Can you say a few words about that paper?
Dr Sharon Reimold: Sure. It's been known for a long time that if you perform catheterizations on men versus women with similar presentation ... Women may not have as much obstructive disease. This particular manuscript explores coronary flow reserve and identifies this as being part of the difference between men and women in that regard. That, obviously, could have important implications for the clinical care of these patients.
Dr Carolyn Lam: I like that. All these papers really took what we may have known a bit before, but took them to a deeper level and in a very novel way. So important. You mentioned some of the novel aspects that were also explored in the issue, the pregnancy related factors, in fact, novel risk factors that we should be taking note of in women. Do you want to comment on a few highlights?
Dr Sharon Reimold: The relationship of pregnancy complications to long term, both maternal and offspring health has been around for a while, but really, we don't know very much about it. We, certainly, have known previously that women with preeclampsia, or those who have significant hypertension, or diabetes in pregnancy may have later problems when they are in middle age or older.
What we are learning from some of these new entries into the research domain is that women who have premature labor and delivery are also at risk for having complications, and this sort of fits in the middle. It's not just preeclampsia, or hypertension, or diabetes. It's that you delivered earlier. Then moreover, we have a couple of research focused letters that describe arrhythmias in pregnancy and what happens to those women during pregnancy. I think we all have seen young women come in and have symptoms, but we really don't know what their outcome has been because any single physician probably just sees a few of them. This highlights arrhythmias as a issue in that population.
We also looked at other articles that focused on other risk factors for heart disease, ranging from breast arterial calcification to traditional biomarkers that we may be drawing in hospital, BMP, troponin, and such. There's a nice manuscript that focuses on hormone changes in women and how they're associated with development of cardiovascular disease. So a fairly broad look at a variety of different risk factors that we don't think about when we're simply asking, "How old are you? What's your blood pressure? What's your diet? Do you have diabetes, and do you have lipid disorders?"
What I would hope that we would get out of this is to open all of our minds and our approaches to patients to think about asking about their pregnancies, did they have any complications, figuring out if they have any hormonal issues, and then being free to consider whether or not the woman that you have in front of you actually has obstructive disease or perhaps has issues with abnormal flow reserve.
Dr Carolyn Lam: Exactly. I would, actually, add to that, also, looking at our commonly used cardio metabolic biomarkers with the lens of realizing that there are important sex differences in all these biomarkers. That was a very nice paper, corresponding author, Dr. James de Lemos. All these papers are just so practical.
I'm actually going to switch tracks now, Sharon, because I really want to talk about this final paper. All I need to do is read the title of the editorial and it’ll be self-evident. "Women are less likely than men to be full professors in cardiology. Why does this happen and how can we fix it?" I love that you invited this editorial. Could you tell us a bit about the paper that sparked this editorial and your thoughts on this?
Dr Sharon Reimold: Yes. The original article has as its first author, Dr. David Blumenthal. It's an article that's one of a series of manuscripts that looked at academic cardiologists and looked at faculty rank where they were able to gather data on sex differences, clinical productivity, research funding, publications, et cetera. They have looked at other disciplines other than cardiology, but this particular manuscript focuses on cardiologists. What it demonstrates is that we are getting, perhaps, a little bit more women in at the assistant professor level, but there’s still a significant lag at the full professor level.
In fact, in many centers if you query development offices, there's probably at least a seven year lag between women and men in terms of making it through the whole spectrum. While perhaps, this is not new conceptually, I think it does quantitate it for us and it highlights the concept that this is an issue now, similarly to what it was 25 years ago when I was a cardiology fellow.
The interesting compliment to this is the editorial by Dr. Karns and Dr. Bairey Merz which tries to go into why does this happen and how can we fix it. They took a very academic approach to their editorial in terms of looking at data and then talk about implicit bias and how even a very small degree of implicit bias will cause men to be promoted, perhaps more in a faster manner than in women, and also bring up some things we don't even think about. One of the best ones was the concept that you advertise for a new position as a cardiologist. If you advertise for someone and you list the skills you want and what you want to build, then that's a more gender neutral way to approach a job. If you advertise for a dynamic, outgoing, I don’t know, vigorous sort of person, and there are ads out there that read like that, you are, inadvertently, advertising for a man, most of the time.
Dr Carolyn Lam: Male characteristics.
Dr Sharon Reimold: Yeah. They talk about that. Then they obviously end up with how can we fix it? I think that's a real challenge.
There are some data within the field of literature for development that suggest that mentoring and coaching are important, but that they don't necessarily push people up the ladder very rapidly. There are some places, for instance, our University of Texas system now that is very interested in the concept of sponsorship. That someone sponsors another individual, could be male or female, to get involved and pushes them ahead, not pulls them, so that they have opportunities for faster career development and success. In any event, I think this compliment of paper and editorial really highlights an issue that, while not necessarily affecting female patients, certainly affects cardiology as a destination career.
Dr Carolyn Lam: I agree. I think part of the how to fix it is simply by being aware and acknowledge the issue. That is exactly what we’re doing in these papers. I love that they are academically written. Like you said, you read a lot about these gender biases in the popular press, but it's so refreshing to see it addressed in an editorial, in a beautiful paper, in circulation.
Sharon, congratulations on just this excellent, excellent issue. Is there anything else you may want to highlight about the issue?
Dr Sharon Reimold: I think that's the major thing. I think we moved a long way from the beginning of Go Red For Women as a campaign where we really wanted patients to be aware that hypertension or elevated cholesterol levels were an important issue. I think now is a time where we move forward. We’ll learn more about differences between men and women and we figure out how we can treat or account for these differences as we strive to make health care for all and cardiovascular care for all improve over time.
Dr Carolyn Lam: Thanks Sharon. Everyone of you listening to this, go pick up this issue. I'm sure we've peaked your interest.
Thank you for listening to Circulation On The Run. Don't forget to tune in 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 Centre and Duke-National University of Singapore. Our featured discussion today relates to 20 year outcomes after mitral valve repair versus replacement for severe degenerative mitral regurgitation.
But first, here's your summary of this week's issue. The first paper suggests that agonistic angiotensin receptor autoantibodies may be biomarkers of adverse outcomes. In this study from first author Dr. Abadir, corresponding author Dr. Fedarko, and colleagues from Johns Hopkins University School of Medicine in Baltimore, Maryland, authors developed a quantitative immunoassay for measuring agonistic angiotensin AT1 receptor autoantibodies in the serum.
They then assessed its operating characteristics in a discovery group of 255 community dwelling adults from Baltimore and validated these findings in a second group of 60 individuals from Chicago. They found that AT1 receptor autoantibody levels were significantly associated with higher levels of inflammatory cytokines, weaker grip strength, slower walking speed, higher risk for frailty, more falls and increased mortality.
Furthermore, chronic treatment with angiotensin receptor blockers, it attenuated the AT1 receptor autoantibody association with decline in grip strength and increased mortality. These results therefore suggest that followup studies and intervention trials in chronic inflammatory diseases should test whether AT1 receptor autoantibody levels can be used to stratify patient risk and whether they can be used to identify patients who may benefit from angiotensin receptor blocker treatment.
The next paper suggests that baseline target mismatch on CT perfusion imaging may predict the response to tenecteplase in ischemic stroke. Dr. Bivard and colleagues from John Hunter Hospital University of Newcastle in Australia pooled two clinical trials of tenecteplase compared with alteplase for the treatment of acute ischemic stroke.
Baseline CT perfusion was analyzed to assess if patients met the diffused two target mismatch criteria. These criteria are absolute mismatch volume of more than 15 mL, mismatch ratio of more than 1.8, baseline ischemic core less than 70 mL and volume of severely hypoperfused tissue less than 100 mL.
Among 146 pooled patients, 71 received received alteplase and 75 received tenecteplase. Overall tenecteplase treated patients had greater early clinical improvement by NIH Stroke Scale change and less parenchymal hematoma, but did not show a significant difference in three month patient outcome by the Modified Rankin Scale.
74 of the 146 patients met target mismatch criteria. It was only among these patients with target mismatch that treatment with tenecteplase result in greater early clinical improvement and better late independent recovery than those treated with alteplase. In summary, tenecteplase may offer an improved efficacy and safety profile versus alteplase, benefits that are possibly exaggerated in patients with baseline CT perfusion defined target mismatch.
The next study is the first to provide a comprehensive analysis of circulating metabolite levels and relate these to clinical outcomes in patients with pulmonary arterial hypertension. First author Dr. Rhodes, corresponding author Dr. Wilkins and colleagues from Imperial College London conducted a comprehensive study of plasma metabolites using ultra-performance liquid chromatography mass-spectrometry in 365 patients with idiopathic or heritable pulmonary arterial hypertension and 121 healthy controls.
They found that increases in circulating modified nucleosides originating from transfer RNAs, energy metabolism intermediates, tryptophan and polyamine metabolites and decreased steroids, sphingomyelins and phosphatidylcholines independently discriminated pulmonary arterial hypertension from controls and predicted survival. Furthermore, correction of metabolite levels overtime was linked to better clinical outcomes and patients who responded well to calcium channel blocker therapy had metabolic profiles comparable with healthy controls, thus these findings suggest that monitoring plasma metabolites overtime could be useful to assess disease progression and response to therapy in pulmonary arterial hypertension. Therapeutic strategies targeted against metabolic disturbances, particularly translational regulation and energy metabolism, may merit further investigation in pulmonary arterial hypertension.
The final study takes a contemporary look at age associated changes in left ventricular diastolic function. Dr. Shah and colleagues from Brigham and Women's Hospital in Boston, Massachusetts related diastolic measures including tissue Doppler E prime, E to e prime and left atrial size, to the risk of heart failure hospitalization or death in 5801 elderly participants in the ARIC study. They further defined sex-specific 10th percentile limits in 401 participants free of cardiovascular disease or risk factors. They found that each diastolic measure was robustly associated with incident heart failure hospitalization or death. Reference limits for E to e prime and LA size were generally in agreement with existing guidelines, whereas limits for tissue Doppler E prime were substantially lower at 4.6 for septal E prime and 5.2 for lateral E prime in the ARIC study compared to 7 and 10 respectively in international guidelines. Compared to the guideline cut points, the ARIC base limits improved risk discrimination and reclassified over one-third of the study population as having normal diastolic function. These findings were further replicated in the Copenhagen City Heart Study.
In summary, this study suggests that a decline in left ventricular longitudinal relaxation velocity occurs maybe as part of healthy aging and is largely prognostically benign. This supports the use of age-based normative values when considering an elderly population.
Well, that wraps it up for the summaries, now for our featured discussion.
Today we are discussing the very important result of the mitral regurgitation international database and we have with us today no other than the corresponding author Dr. Jean-Louis Vanoverschelde, and he is from University of Louvain in Brussels. Welcome Jean-Louis, I made it.
Dr Jean-Louis Vanoverschelde: Hey, how are you?
Dr Carolyn Lam: Thank you so much for joining us. Also joining us today is Dr. Victoria Delgado, associate editor from Leiden University Medical Center in the Netherlands. Welcome Victoria.
Dr Victoria Delgado: Hello. Thank you very much for having me in this podcast.
Dr Carolyn Lam: So, severe degenerative mitral regurgitation with flail leaflets, a very important condition and your study, Jean-Louis, really provides important clinically applicable information. Could you please address our clinicians out there with a take home message from your paper.
Dr Jean-Louis Vanoverschelde: Well, the take home message is very easy, once this condition needs to be operated on, there are really two options, one which is to repair the valve and keep the native tissue and the other is to replace the valve and trash the native tissue if I can say so. The results of the study are really clear. There is a major survival advantage by repairing the valve as opposed to replacing it. So for everyone of those who have degenerative mitral regurgitation with flail leaflets, the best treatment option is mitral repair.
Dr Carolyn Lam: Now these results came from a multi-center registry of thousands of patients. I was really struck with the duration of the study. I think that's something that's really novel. You had a 20 year follow up but also patients were recruited from 1980 all the way to 2005, am I right? So could you expand a little bit about the possibility of techniques changing during that period?
Dr Jean-Louis Vanoverschelde: Although there has been subtle changes in the practice, the basic principle have remained the same. So we have not really accounted for these changes in the practice over time, with regard to what happened to mitral valve replacement, clearly the prostheses that were there 30 years ago are not the same as the ones that are currently implanted to the patients, but none the less when we performed an analysis, a sensitivity analysis to look at whether the results were different from 20 years ago compared to those that were more recent, we found exactly the same result.
Dr Carolyn Lam: Yes, I thought that was a very important sensitivity analysis. Tell us a bit more about the propensity score matching as well because another thing people will be thinking is, you know, this is a registry, huge numbers very important but obviously there would be differences in indication for repair versus surgery.
Dr Jean-Louis Vanoverschelde: For sure, the fact is that there are statistical means that allow you to mimic not to be the exactly the same as, but to mimic randomization and it is the propensity score matching. That means that you perform a prior analysis that will identify similar patients in the two cohorts and match them so that you are basically having the same kind of patients that are treated with two different ways. So it's not randomization but it’s getting close to randomization when you use cohorts like the one from the MIDA registry.
Dr Carolyn Lam: Perfect. Victoria, did you take the same take home messages and are you applying this clinically? I noticed that you invited an editorial, a lovely editorial on this paper as well, so please share your thoughts.
Dr Victoria Delgado: Yeah, I share the same take home message that Dr. Vanoverschelde has outlined. I think that this is very important article, it's a landmark article highlighting one of the most important things that mitral valve repair should be probably the standard of care for patients with severe mitral regurgitation without degenerative cause with a flail and the article basically what it does is also endorsing the recommendations of current guidelines highlighting the value of mitral valve repair. Of course that mitral valve repair should be performed in centers with experience and with good durability of these repairs, so the centers need to have a good heart team where they can analyze their results in such a way like the MIDA registry has done demonstrating a good durability of the repair.
Dr Carolyn Lam: And do you have anything to add to that Jean-Louis?
Dr Jean-Louis Vanoverschelde: No, I think basically Victoria very well summarized the basic features not only of the paper itself but also of the condition and what currently is in the guidelines. In fact, the guidelines have already said that we should be preferring mitral valve repair over replacement, but the data on which this was based were probably not as conclusive as the one that are provided by this analysis of our registry, so I think it's really reinforcing the idea that we should go ahead and try to perform repair as much as possible, now with a caveat of course that the surgeons need to be skilled enough to perform that. But with the type of differences that we see in survival between the two cohorts I think that if a surgeon does not feel comfortable with repairing the valve and would rather replace it, he might refer the patient to another surgeon that is capable of repairing the valve. The impact and outcome is such that I think this really supports the idea that the patient should be referred to high volume and skilled centers.
Dr Carolyn Lam: Could you give us an idea of what kind of impact you're talking about, what kind of numbers that you see?
Dr Jean-Louis Vanoverschelde: It's the same in all the analysis, whether it's in the overall population or in the matched cohorts by 20 years, we have something like 20 to 25% survival difference, absolute survival difference between the two groups. So it's a reduction of mortality approximately by half if you perform repair compared to replacement, and it is increasing with time, so it's not something that is only present in the first years but is increasing with time, so it's about 20 to 25% absolute difference between the two cohorts.
Dr Carolyn Lam: That truly is remarkable. Congratulations again on such a landmark paper like Victoria said. Now to either of you, question that's a bit left field maybe, but what do you think the role is now for percutaneous techniques of mitral valve repair or replacement then?
Dr Jean-Louis Vanoverschelde: That's an interesting question. I think that if you really look far away into the future probably everything at some point in time will be percutaneous. At this stage I’m not sure that the percutaneous technique able to mimic what we can do with surgery in terms of mitral valve repair. So, it's an alternative to surgery in patients who are inoperable. In those who can undergo a surgical mitral repair, my first choice will certainly be to go surgically rather than percutaneously, at least right now.
Dr Carolyn Lam: Victoria?
Dr Victoria Delgado: I also agree with those comments. I think that now we have a lot of possibilities to treat these patients but the most important thing is to have the entire clinical picture of the patient, to see the pros and cons of preparing the patient for surgery or for percutaneous valve. There should be also an integration of imaging to know which is the cause of the valve dysfunction and to see whether the anatomy could be easily repaired by surgery or instead if the patient has contraindication for surgery, if it could be repairable as well with transcatheter therapy. But then for that I think that is really important and this is what the editorial also highlights, the role of the heart team, where there are different specialist surgeons, clinical cardiologists, heart failure specialists, imaging specialists that can integrate the entire information of the patient in order to select the most appropriate therapy. But still for patients who do not have contraindications for surgery who have repairable valve and as you can see from this registry, the percentage of repairability is quite high, I would still refer the patient as well for surgical valve repair.
Dr Carolyn Lam: You heard it right here. Thank you so much for joining us today and please don't forget to tune in 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 Centre and Duke-National University of Singapore. In just a moment, we're going to be discussing new results of the pioneer trial, and the patient with atrial fibrillation who undergoes intracoronary stenting, a familiar conundrum. What's the role of NOACs? Is there still a role for full-dose triple therapy with warfarin? First, here's your summary of this week's journal.
The first paper tells us about the clinical impact of left atrial appendage closure. Dr. Melduni and colleagues from the Mayo Clinic in Rochester, Minnesota, studied 9,792 patients undergoing bypass or valve surgery between 2000 and 2005. They used propensity score matching to estimate the association of left atrial appendage closure with early post-operative atrial fibrillation- defined as atrial fibrillation within 30 days of surgery- ischemic stroke, and mortality. They found that after adjustment for treatment allocation bias, left atrial appendage closure during routine cardiac surgery was significantly associated with an increased risk of early post-operative atrial fibrillation, and did not influence the risk of stroke or mortality.
They therefore concluded that it remains uncertain whether prophylactic exclusion of the left atrial appendage is warranted for stroke prevention during non-atrial-fibrillation-related cardiac surgery.
The next study provides pre-clinical evidence that genes on sex chromosomes may contribute to the sexual dimorphism of abdominal aortic aneurysms. That is, we well know that abdominal aortic aneurysm is a male-predominant disease. Now, in this paper, by first author Dr. Alsiraj, corresponding author Dr. Cassis and colleagues from the University of Kentucky, female LDL-receptor-deficient mice, with an XX or XY sex chromosome complement, were infused with angiotensin II for 28 days to induce abdominal aortic aneurysms. DNA microarrays were performed on the abdominal aortas, and to mimic the males, the female mice were administered a single dose of testosterone.
They found that an XY sex chromosome complement, in phenotypic females, profoundly influenced aortic gene expression profiles and promoted abdominal aortic aneurysm severity. When XY females were exposed to testosterone, aneurysm rupture rates were striking. The mechanisms for augmented abdominal aortic aneurysm severity in XY females included increased inflammation, augmented matrix metalloproteinases, and oxidative stress. These results, therefore, demonstrate that genes on the sex chromosomes regulate aortic vascular biology and contribute to sexual dimorphism of aortic abdominal aneurysms. Sex chromosome genes may therefore serve as novel targets for sex-specific abdominal aortic aneurysm therapeutics.
The next two studies shed light on the mechanism of action of PCSK9 monoclonal antibodies on lipoprotein metabolism. In the first study, Dr. Watts and colleagues from University of Western Australia carried out a two-by-two factorial trial, of high-dose atorvastatin versus evolocumab on stable isotope tracer kinetics in 81 healthy, normal lipidemic, non-obese men.
They found that both atorvastatin and evolocumab independently accelerated the fractional catabolism of VLDL apoB, IDL apoB, and LDL apoB. On the other hand, evolocumab, but not atorvastatin, also decreased the production rate of IDL apoB and LDL apoB. The reduction of LDL apoB and LDL cholesterol was significantly greater with a combination versus either mono-therapy. In summary, they found that in healthy, normal lipidemic men, evolocumab decreased the concentration of atherogenic lipoproteins, particularly LDL, by accelerating their catabolism, and by reducing IDL and LDL production. The latter effects are incremental to statins.
The second paper to deal with this topic comes from Dr. Ginsberg and colleagues from Columbia University in New York, who studied 18 participants, this time 10 of whom were women, who completed a placebo-controlled two-period study, receiving two doses of placebo followed by five doses of alirocumab. These authors found that alirocumab decreased LDL cholesterol and LDL apoB by increasing IDL and LDL apoB fractional clearance rates, and by decreasing LDL apoB production rates. These results were consistent with increases in LDL receptors available to clear IDL and LDL from the blood during PCSK9 inhibition. These two papers are discussed in a beautiful accompanying editorial by Dr. Chris Packard from University of Glasgow. In his editorial entitled "Unpacking and Understanding the Impact of PCSK9 Inhibitors on Apolipoprotein B Metabolism." Those were your highlights! Now for our feature discussion.
Today we are going to be discussing one of the most common conundrums in all of cardiovascular medicine, and that is the care of patients with atrial fibrillation who also need percutaneous coronary intervention. Of course, both dual antiplatelet therapy and oral anticoagulation therapy would be indicated to reduce the risk of stent thrombosis and thromboembolism in atrial fibrillation, respectively. However, with the intensification of the anti-thrombotic regimen, there is the inevitable trade-off with more bleeding. Now, to discuss this, we have the first and corresponding author on a very novel study of the pioneer trial, and that is Dr. Michael Gibson, from Harvard Medical School and Beth Israel Deaconess Medical Center. We also have the editorialist for this very exciting paper, Dr. Deepak Bhatt from Brigham and Women's Hospital, and finally, we have Dr. Dharam Kumbhani, associate editor from UT Southwestern. Welcome, gentlemen!
Dr Deepak Bhatt: Thank you.
Dr Michael Gibson: Thanks.
Dr Dharam Kumbhani: Thank you.
Dr Carolyn Lam: So, Michael, could I start with you? This is a sub-study of the pioneer study. Could you tell us how this is different from the primary results, what were you looking for, and what you found?
Dr Michael Gibson: As you know, as [inaudible 00:07:40] said, we have a lot of bleeding with conventional triple therapy, and we used two regimens to try and reduce that bleeding. One was a reduced dose of rivaroxaban, 15 milligrams, plus thienopyridine. The other strategy was baby dose rivaroxaban, 2.5 milligrams twice a day, plus DAPT. What we found in the overall study was a significant reduction in bleeding- from, say, 26.7% down to 18% for riva plus DAPT- that's the baby dose plus DAPT- and down to 16.8% for the 15 milligrams of riva plus the thienopyridine.
You'd have to treat about 11 to 12 patients to prevent one significant bleeding event. That's the mainstay. What we found in this very, very important sub-study is that that was associated with reduction in hospitalization. All-cause hospitalization was reduced, and cardiovascular hospitalization went down from 28.4% to about 20% for the two regimens. Bleeding with hospitalization went down, from 10.5% to about 6%. At the end of the day, you'd only have to treat 10 to 15 people to prevent one hospitalization, so from a health economic perspective, and from a patient viewpoint and hassle perspective, this was very important.
Dr Carolyn Lam: In fact, Michael, I would say from a clinician-cardiologist perspective, these results are really very applicable. In fact, I really like, in the accompanying editorial, what Deepak wrote, that it may be one of those rare occasions where a sub-study provides very clinically meaningful information compared to the primary study. Deepak, would you like to elaborate a little bit more about that?
Dr Deepak Bhatt: Sure. A really great point that you've raised. It wasn't, in fact, a sub-study we're talking about in Circulation. It was an analysis from the overall trial, looking at a different endpoint than the primary endpoint, the hospitalization, and the composite of hospitalization and mortality. I think that's a very important endpoint. If it were a heart failure trial, for example, that's the endpoint everyone would hone in on- mortality and hospitalization. The fact that that was significantly reduced, I think, is very clinically meaningful. Mike mentioned the economic implications, which for sure are there, by reducing hospitalizations and re-hospitalizations.
The impact on cardiovascular hospitalizations- the reduction there- I find particularly remarkable. The reduction in bleeding, of course, is good, and in its own right has a great deal of value, but the additional reduction in cardiovascular hospitalizations, I think, is quite reassuring for those that are worried about the efficacy of the two experimental regimens that he and his colleagues studied. Sure, the trial's not powered in each individual sub-group for rare events like stroke, but the fact that CV hospitalizations are not increased, and in fact reduced, tells me that this is a winning strategy or strategies.
Dr Carolyn Lam: Right. Michael, another issue, though- this is open label, and I suppose one of the criticisms could be that there is a bias for clinicians managing patients on the traditional Vitamin K antagonist to maybe hospitalize patients more for some reason. What is your response to that?
Dr Michael Gibson: That is always the criticism of an open label trial, but again, the events were adjudicated, and for the heart events, that's done in a blinded fashion, so it's reassuring that there was a blinded assessment of the heart events.
Dr Carolyn Lam: True. How about comments on generalizability? I mean, what do you think? Trial setting, real world ...
Dr Michael Gibson: Yeah, I think that's one of the advantages. This was very much a real-world kind of study. It was truly done throughout the world. We had a very broad entry criteria. Anyone who was getting a stent put in- you didn't have to have ACS, although about half the patients did. The only real exclusive criteria was you couldn't have any bleeding or be profoundly anemic. You couldn't have a stroke or [TIA 00:11:58] in the past. Other than that, it made real-world practice in a lot of ways.
Dr Dharam Kumbhani: This is Dharam. If I may ask both the other people on the call, is ... Rivaroxaban is not FDA approved, in these doses, for use. I'm wondering if they might provide some comment, given the benefit that we see in this trial, overall, what their thoughts are and what the next steps might be.
Dr Carolyn Lam: Sure. Maybe Michael, then Deepak?
Dr Michael Gibson: Yeah, that's a good point. It is important to point out that you'd need to check the prescribing information in your country. In some countries- I think it's about 54 countries- the 2.5 milligram dose is available. It is approved for ACS, but is not approved for a-fib. Then, you have a dose of 20 milligrams that's approved worldwide for a-fib, but there are some countries- it's important to note, in some countries, 15 milligrams is the full dose that's approved- say, in Japan and Taiwan. There are Japanese studies showing that 15 milligrams was not only safer than warfarin, but more efficacious than warfarin in a trial like J-ROCKET. You're right, the 15 milligram dose is available in the US- it's approved for renal insufficiency, but at this time, it's not labelled for the ACS or stented patient.
But again, physicians are at liberty to look at this data, which is the first real data that we have to guide decision-making in this setting, and they're at liberty to make their own choices.
Dr Deepak Bhatt: Yeah, I would agree with that assessment, and emphasize ... Like Mike said, it's an international audience for Circulation, so I would say, look in your own country, and in many parts of Europe, the 2.5 milligram rivaroxaban dose is available and approved for ACS, and could therefore be used for this purpose, though not strictly falling within the label indications. In the US, there's the 15.
I think, if I just answer the previous question, the results are very generalizable, and for doctors that critique that point, I'd say, "Why didn't you enroll your patients in the trial?" There's the RE-DUAL as well, that's ongoing, with dabigatran, AUGUSTUS with apixaban, and I'm missing one that's also ongoing as well, I think, but there are four different trials that are out there. The Pioneer was the first to report ...
Dr Carolyn Lam: I think you're thinking of the Entrust AF-PCI with Edoxaban.
Dr Deepak Bhatt: The most recent one, yes. I forgot the acronym, there. If people are really thinking that the results don't apply to their patients, well, there are trials that are ongoing. Enroll your patients. But to say, "Oh, my patients, I'm not going to enroll them in the trial," and then say, "The results aren't generalizable," I always find that an odd thing. I think the results are very generalizable. The one word of caution I would say, though, is to make sure to renally dose, as was done in the trial. That is, there was a downward adjustment in dose from the 15 milligrams to the 10. In real life, we've seen in registries with NOAC use, whether it's rivaroxaban or any of the others, a lot of times, the renal function is not carefully monitored in those patients that are on the fringe in terms of their renal function, and that's the one situation NOACs can backfire, where the dose isn't corrected for their degree of renal dysfunction. Other than that one caveat, I think the results are quite generalizable.
Dr Carolyn Lam: Excellent comments. We should wrap up soon, but not before I want to ask Dharam. Thank you for managing this beautiful paper. What, to you, is the take-home message for clinicians out there?
Dr Dharam Kumbhani: Yeah, it was an absolute honor and delight to manage this, and I think the paper's great. The editorial's great. It's gotten a great response. I think the take-home message is that this is a very clinically relevant question, and a very clinically relevant trial, and it shows that the needle will be moving towards using non-VKA-based agents, especially in patients such as this, who have both a-fib and PCI. I think this is very exciting space, a very important space. This trial suggests that if you use the strategy rivaroxaban low dose, with or without a DAPT, that it is safer, both in terms of mortality and bleeding, compared with what is traditionally being used with warfarin plus DAPT. I think this was a very, very exciting trial.
Dr Carolyn Lam: Indeed, and congratulations to all three of you. Thank you so much for joining me on Circulation On The Run. Thank you, listeners, for joining us too, and don't forget to tune in 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. Dr. Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
In today's episode, we are discussing very important new data regarding stroke risk stratification in patients with atrial fibrillation. First though, let me give you the highlights of this week's journal.
The first paper provides mechanistic evidence that endothelial-derived microparticles may play a key role in the development of endothelial dysfunction following acute coronary syndrome. In this paper from first author, Dr. Abbas, co-corresponding authors, Dr. Toti and Morel from the University of Strasbourg in France, authors expose core sign coronary artery endothelial cells to microparticles shed from senescent cells, or circulating microparticles from patients with acute coronary syndrome.
They showed that exposure to these microparticles induced increase senescence-associated beta-galactosidase activity, oxidative stress, and early phosphorylation of MAP kinases and AKT, and upregulation of p53, p21 and p16. Depletion of endothelial-derived microparticles from acute coronary syndrome patients reduced the induction of senescence.
On the other hand, pro-senescent microparticles promoted endothelial cell thrombogenicity. These microparticles exhibited angiotensin-converting enzyme activity and upregulated AT1 receptors and ACE in endothelial cells. Losartan and AT1 receptor antagonist and inhibitors of either MAT kinases or PI3-kinase prevented the microparticle-induced endothelial senescence.
In summary, these findings indicate that endothelial-derived microparticles from acute coronary syndrome patients induce premature endothelial senescence and thrombogenicity suggesting that targeting endothil-derived microparticles and their bioactivity may be a promising therapeutic strategy to limit the development of endothelial dysfunction post-acute coronary syndrome.
The next study is the first large and prospective study showing that NT-proBNP is associated with cardiovascular events in patients with adult congenital heart disease independent of multiple clinical and echocardiographic variables.
This is a study from first author, Dr. Bekan; and corresponding author, Dr. Roos-Hesselink and colleagues from the Erasmus University Medical Center in Rotterdam, the Netherlands. The author studied 595 clinically stable patients with adult congenital heart disease who attended the outpatient clinic between 2011 and 2013.
All patients underwent clinical assessment, electrocardiography, echocardiography and biomarker measurement, including NT-proBNP, high-sensitivity troponin T and growth differentiation factor 15. Patients were prospectively followed over a median of 42 months for the occurrence of cardiovascular events including death, heart failure, hospitalization, arrhythmia, thromboembolic events and reintervention.
They found that of the three evaluated biomarkers, NT-proBNP was most strongly associated with cardiovascular events. Importantly, patients with a low-risk of death and heart failure could be accurately identified with a high negative predictive value.
In patients with elevated NT-proBNP, elevations of high sensitivity troponin T and growth differentiation factor 15 identified those patients at highest risk of cardiovascular events.
In summary, these biomarkers may play an important role in the monitoring and management of patients with adult congenital heart disease.
The next study describes heart failure stages among older adults in the community. Dr. Shah and colleagues from the Brigham and Women's Hospital in Boston Massachusets classified more than 6,000 participants in the atherosclerosis risk and community study into heart failure stages. These were stage A; asymptomatic individuals with heart failure risk factors, but no cardiac structural or functional abnormalities. Stage B; asymptomatic individuals with structural abnormalities such as left ventricle hypertrophy, dilation, dysfunction, or valve disease. Stage C1; clinical heart failure without prior hospitalization. Stage C2; clinical heart failure with prior hospitalization.
They found that only 5% of examined participants were free of heart failure risk factors or structural heart disease. 52% were categorized as stage A, 30% stage B, 7% stage C1, and 6% stage C2. Worst heart failure stage was associated with a greater risk of incident heart failure hospitalization or death at a median follow up of 608 days.
Left ventricular ejection fraction was preserved in 77% of stage C1 and 65% of stage C2 respectively. In corporation of longitudinal strain measurements and diastolic dysfunction into the stage B definition, reclassified 14% of the sample from stage A to B.
Abnormal LV structure, systolic function, whether based on ejection fraction of longitudinal strain, and diastolic dysfunction, were each independently and additively associated with the risk of incident heart failure hospitalization or death in stage A and B participants.
The authors concluded that the majority of older adults in the community are at risk of heart failure, appreciably more compared to previous reports in younger community-based samples. The study also highlighted the burden of heart failure with preserved ejection fraction in the elderly and provided evidence that left ventricular diastolic function and longitudinal strain provide incremental prognostic value beyond conventional measures of LV structure and ejection fraction in identifying patient at risk of heart failure hospitalization or death.
The next study sheds light on the association of the LPA gene, ethnicity and cardiovascular events. First author, Dr. Lee; corresponding author Dr. Tsimikas and colleagues from University of California San Diego studied 1,792 black, 1,030 white, and 597 Hispanic subjects all enrolled in the Dallas Heart Study. They measured LPA snips, apolipoprotein A isoforms, LP(a) and oxidized phospholipids on apolipoprotein B100.
These individuals were also followed for a median of 9.5 years for major adverse cardiovascular events. The authors found that the prevalence of LPA snips and apolipoprotein A isoforms were very different across ethnic groups. LPA snips that were associated with elevated LP(a) in whites were associated with low LP(a) in Hispanics mainly due to differences in apoliproprotein A isoforms size.
After multi-variable adjustment, LP(a) and oxidized phospholipids on apolipoprotein B were both predictors of major adverse cardiovascular events. Conversely, LPA snips and apolipoprotein A isoforms did not add predictive value to models and did not show clinical utility in this study.
These data suggests that much of LP(s) mediated major adverse coronary events is driven by oxidized phospholipids. Importantly, elevated LP(a) and oxidized phospholipids on apolipoprotein B must be recognized as important predictors of major adverse cardiovascular events across racial groups.
The final study addresses the question of the optimal antithrombotic regimen for longterm management of patients with symptomatic peripheral artery disease, or PAD, with a history of limb revascularization. To answer this question, Dr. Jones and colleagues from Duke Clinical Research Institute looked at the EUCLID trial, or examining use of ticagrelor in PAD trial, which randomized patients with PAD to treatment with ticagrelor 90 milligrams twice daily, or clopidogrel 75 milligrams daily.
As a reminder, patients in EUCLID were enrolled based on a normal ankle-brachial index of less .8, or a prior lower extremity revascularization. The current paper really focus on the subset of 7,875 patients who were enrolled based on a prior lower extremity revascularization criterion.
The authors found that after adjustment for baseline characteristics, patients enrolled based on prior revascularization for PAD had higher higher rates of myocardial infarction and acute limb ischemia with similar composite rates of cardiovascular death, myocardial infarction and stroke when compared with patients enrolled based on the ankle brachial index criterion.
Overall, there were no significant differences between ticagrelor and clopidogrel for the reduction of cardiovascular or acute limb events.
Those were your highlights. Now, for our featured discussion.
On today's podcast, we are discussing the very, very important issue of stroke risk in patients with atrial fibrillation. Most of us use the international guidelines for anticoagulation in atrial fibrillation that mostly suggest that we use the CHADS VASc scoring system to determine the stroke risk in a particular patient and then determine whether or not this patient meets the threshold for anticoagulation.
This assumes that the CHADS VASc score corresponds to a fixed stroke rate. Today, in our journal, we have very, very interesting results from a paper with corresponding author, Dr. Daniel Singer who really suggest that we may need to rethink that. Dr. Daniel Singer joins us today from Massachusets General Hospital.
Dr. Daniel Singer: Thank you for having me.
Dr. Carolyn Lam: Great. Today, we also have Dr. Sana Al-Khatib who's the associate editor from Duke University who managed this paper. Welcome Sana.
Dr. Sana Al-Khatib : Thank you Dr. Carolyn, I'm happy to be here.
Dr. Carolyn Lam: Daniel, could we start by you letting us know what you sought to do in your study and what you found?
Dr. Daniel Singer: We all know that anticoagulants are extraordinarily effective at preventing stroke in patients with atrial fibrillation, but they also raise the risk of bleeding, and sometimes that bleeding could be quite serious and even fatal. As a result, for that past 10, 15 years, we have used a risk-based approach to the decision about whether to start a patient on anticoagulation, and that risk is the stroke risk that a patient faces if they weren't taking anticoagulants. Then we figured that anticoagulants will reduce it by about two-thirds.
There are formal decision analysis and then a more informal sense that a patient has to face an anticoagulated risk of stroke of about 2%, some people might say 1% to 2% before anticoagulation results in an expected net clinical benefit that the effect in reducing ischemic stroke will exceed the risk of increasing bleeding.
While the CHADs VASc score has been widely accepted as the basis for estimating that risk, it became apparent to us as we looked across the studies that were underlying that assumption, that the risk that were associated with various CHADs VASc scores were extremely variable. Many of these risks actually were less than that 1% or 2% threshold for anticoagulation.
What I mean is that the stroke risk associated with CHADs VASc score of one, or two, which is the basis for the guideline threshold for anticoagulation actually corresponded to risk less than 1% in many of these very large studies. We have conducted a systematic review just to be sure that we were capturing the overall evidence base for this, and that's what we report in our paper.
Dr. Carolyn Lam: Perhaps you could start by letting us know exactly how far off are we in our stroke risk estimation.
Dr. Daniel Singer: We looked at 34 studies that were quite large and then we zeroed in on the largest one. If you looked at the rate for stroke overall, they varied enormously in terms of the overall stroke rate. Then when we focused down on CHADs VASc score of 1, or 2, we found that the majority of these studies, actually, for CHADs VASc 1, was less than 1% per year. For CHADs VASc 2 score was in the majority these studies less than 2% per year.
Both of those stroke risks have raised us the question where are these patients could gain in that clinical benefit from being anti-coagulated, because those stroke risk, if they were reduced by two-thirds, would really be a very small reduction in risk and yet they'd still face the bleeding risk.
Among the most interesting findings actually is that we found that a Swedish national database and the large Danish national database came up with threefold difference in their estimate of stroke rates. The Swedish database produced lower risk, and the Danish database produced substantially higher risk.
If you think about it, there are probably no two countries in the world that are more similar in terms of gene, social environmental, medical care systems, and that raises the specific question of, "Is it underlying rates that vary across different cohorts and different geographies, or is it a different in methodology?"
We think a lot of the differences are due to methodologic difference, and that we need to standardize these differences together, better handle on what the real stroke rate is among patients with these low CHADs VASc scores.
Dr. Carolyn Lam: The variability that you pointed on your paper is really striking, but another possibility, do you think, is that maybe stroke risk isn't static.
Dr. Daniel Singer: Yeah. If that's the case, we face a great difficulty in developing predictions rules of what the stroke risk could be. I think most people feel it's the function of their age, and whether they've had a prior stroke, and whether they have the comorbidity, hypertension, and diabetes, and so on, that are incorporated into the various stroke risk scores, in particular, CHADs VASc.
We tend to think that that's pretty fixed until you get older or until you accumulated another comorbidity. I think the striking difference is that, one, that we actually anticipated in the beginning, was that the stroke rates in people with atrial fibrillation were also coming down. The stroke rates in general have been dramatically decreasing for decades now.
One issue is whether that applies as well to atrial fibrillation associated stroke. There is a suggestion of that, but the variability across the cohorts is so great that you can't pick up a strong signal in terms of calendar time. Although I suspect that there is a strong calendar effect. Exactly why that is, we could speculate. I suspect a lot of it is control of blood pressure, but that's speculation.
Dr. Carolyn Lam: Daniel, congratulations again for that fascinating and really very sobering findings.
Sana, you managed this paper. It's very important paper. In fact, important enough that you invited an editorial. Could you please share some of your thoughts?
Dr. Sana Al-Khatib : Oh, yeah. Absolutely. First, I'd like to start by congratulating Daniel and his team on conducting this really important study. I enjoyed reading it and managing it. Definitely, congratulations.
A couple of thoughts that I have. I completely agree with this really important finding, that there is a lot of variability in the rates of stroke that come from different patient populations and databases. As you pointed out Daniel, I think this is indeed largely due to differences in methodology in terms of how the information was selected, how certain things were defined.
I agree with you there. You called for standardization of this, and I wonder if you have any thoughts about how we can go about doing that. I also want to bring up some of the newer studies now that are showing some significance in terms of biomarkers. Is that really adding significantly to the predictive ability of risk prediction models? I wanted to get your thoughts on that as well.
Dr. Daniel Singer: Let me address your last question, which is simply you state that the CHADs VASc score, the CHAD score and so on, are based on very simple clinical features, and it would be unusual for them to be highly predictive. In fact, they're only mediocrely predictive, and the addition of biomarkers high-sensitivity troponin proBNP, now, people have suggested the imaging biomarkers like magnetic resonance to asses fibrosis in the left atrium. These are all very, very promising in terms of getting better models.
The problem is to do that on a very scale such that we can get precise and well-calibrated predictions. We've found when we're analyzing to pair risk scores, we found that the most important issue is the underlying risk, so that, yes, you can get a great model, but if you have high variability in the underlying rate, you can have a problem specifying an individual with a stroke risk.
We have to standardize and improve the quality of bringing people into these cohorts, and of interrogating the cohorts and databases and making sure that we have the same approach to assessing outcomes.
This could probably be best done in very big scientific prospective registry studies, but it's tough to get all that information. There are some registry studies now ongoing, the ORBIT registries, the GARFIELD registries that may help us a lot with specifying stroke risk, but they don't have the biomarkers embedded in them. I'm hopeful that with better message, and large studies, and incorporating biomarkers, that we'll really get down to very accurate and generalizable stroke risk.
I think the CHADs VASc and similar simple stroke risk scores will be in the rear-view mirror.
Dr. Sana Al-Khatib : That's great. Can I ask one other question, because I completely agree with you looking at your numbers and the data that you presented, is that when you look, especially at the CHADs VASc score 1 patient, the risk seems to be pretty low.
As you very well know, the guideline documents don't really ... At least, for the American AHA/ACC guideline document, they don't really verbalize very definitively the need to anticoagulate patients with a CHADs VASc score of 1.
If you look at the numbers related to a CHADs VASc score of 2, I'm not sure that I completely agree that the risk is very low. Certainly, there was 33% of the studies reported stroke rates of greater than 2% per year. I think maybe different people have different thresholds. While I completely agree with you on the CHADs VASc score of 1 patients, I find that the findings on patients with a CHADs VASc score of 2 a bit more concerning.
In fact, if anything, I would want based even on your data, not on the guidelines to offer anticoagulation to patients with CHADs VASc score of 2. What would you say to that?
Dr. Daniel Singer: I'm looking at our table that has this, and a lot of the CHADs VASc 2 scores are under 2%, but they're in mid 1%. In the North American cohorts in particular, the rates tend to be lower. That said, I think the heart of the problem here is that we have focused on the threshold for anticoagulation. I think there's an argument to be made that you lay out the risks and benefits to the patients and engage them in a decision, particularly with regards to these lower CHADs VASc scores.
At least you make a lot of, perhaps, even more emphasis on being sure that the higher CHADs VASc scores, that anticoagulation is the net benefits of anticoagulation are made very clear to the patient, and that we don't have large fractions of patients who can take anticoagulants not taking them.
We know from the pinnacle registry and other registries, that even at high CHADs VASc scores, we have 40% plus of atrial fibrillation patients who are not getting anticoagulants. I think that's where we have a lot more assurance that the net benefit is positive and that we can make a different both in terms of a patient in front of us, and in terms of the overall public health aspects of atrial fibrillation and stroke.
Dr. Sana Al-Khatib : I do believe that this is really important, but it is also important to keep in mind that with the novel novel oral anticoagulants, I think the whole landscape has changed. Not only do patients have different options to consider, but certainly, the risk of bleeding, which is the other part of this equation, has gone down significantly with the novel agents.
I think as we engage in shared decision making with patients, I think it is really important to highlight these really very remarkable features about the agents that have really changed the care of patients with atrial fibrillation.
One thing to add to this whole topic is, really, all the new advances that we're seeing in this field that has been really life-changing for us and for our patients.
Dr. Carolyn Lam: Indeed Sana. I was about to bring up the bleeding risk part, the flip side of the coin as well. Also, the point that most of my patients with atrial fibrillation, they really strongly value the avoidance of stroke even more than avoidance of bleeding. Someone, that needs to be taken into consideration as well.
Daniel, I'd love to give you the last words. You mentioned that you like to highlight, maybe, some more of the implications of your findings.
Dr. Daniel Singer: I guess I would say there's a scientific implication, which is what we've ben discussing, which is the importance of trying to get these rates down correctly and accurately, and maybe we have to get people together to say how they're doing these studies.
The second is, for the individual patient, that we should engage them in this discussion. Maybe patients who are perfectly willing to a novel anticoagulant and CHADs VASc score of zero. That would come out of a discussion with the patient. That our emphasis at this point since we're a little unsure about the threshold level, our emphasis both at the individual patient level, and then from the public heath perspective should be on the higher CHADs VASc scores where we know that we can expect a net clinical benefit from the vast majority of patients with AF.
I agree with Dr. Al-Khatib, that the novel anticoagulants post an important advantage in the sense not so much in their overall bleeding, but particularly in terms of their intercranial bleeding, which is the lethal bleeding we most want to avoid.
Dr. Carolyn Lam: Thank you both for joining us. Thank you listeners for joining us. Don't forget to tune in next week.
Dr. 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 episode marks the six month milestone of our run together, a run that has taken us around the world from the United States to Europe, South Africa, and Asia, and one that is shared by listeners all over the world.
On behalf of the editors, and from the bottom of my heart, I want to thank you for your support and request that you please subscribe to our podcast and share it with your friends and colleagues. We commit to bringing you the best of cardiovascular science in the most accurate and digestible way possible, thus suiting the busy cardiologist on the run.
Dr. Lam: All right, here are your highlights of this week's issue.
The first paper looks at tissue plasminogen activator, or TPA treatment in ischemic stroke, addressing two aspects that are still unclear. Number one, the degree of additional benefit accrued with treatment in the first 60 minutes after onset of ischemic stroke; and number two, the shape of the time-benefit curve through 4.5 hours. First author, Dr. Kim, corresponding author Dr. Saver and colleagues from UCLA stroke center analyzed more than sixty-five thousand acute ischemic stroke patients treated with intravenous TPA within 4.5 hours of onset from the "Get With the Guidelines" Stroke U.S. National Program.
They found that 878 of these over sixty-five thousand patients were treated within the first 60 minutes after onset, a ten-fold increase over previously available data. Thrombolytic treatment within the first 60 minutes was associated with the highest rates of favorable discharge outcomes. The shape of the time-benefit curve throughout the first 4.5 hours was non-linear for some outcomes. Discharge to home and discharge free of disability decayed more rapidly in the first hundred to a hundred and seventy minutes after onset than later. While independent ambulation at discharge and in-hospital mortality declined in a steady fashion through the time window.
These findings reinforce the importance of quality improvement programs to accelerate door to needle time for thrombolytic therapy in acute ischemic stroke.
Dr. Lam: The next study sheds light on mechanisms underlying red blood cell mediated hypoxic vasodilation. A highly conserved response coupling oxygen delivery to metabolic demands of the tissues, and very clinically relevant in states of systemic hypoxemia and impairment in oxygen delivery, such as in patients suffering from cardiovascular, pulmonary, or hemolytic diseases.
In this paper, Dr. Bailey and colleagues from University of British Columbia Okanagan in Canada studied ten healthy participants who were randomly assigned to a normoxic, or 21% oxygen, and hypoxic, or 10% oxygen trial with measurements performed at rest and following 30 minutes of cycling at 70% of maximal power output. Blood was sampled simultaneously from the brachial artery, internal jugular, and femoral veins with plasma and red blood cell nitric oxide metabolites measured. Cerebral and femoral venous blood flow were determined by transcranial doppler ultrasound and constant infusion thermodilution respectively.
The authors found that hypoxia was associated with a mild increase in both cerebral and femoral blood flow, with further more pronounced increases observed in femoral blood flow during exercise. Plasma nitrite gradients reflecting consumption were accompanied by red blood cell iron nitrosyl hemoglobin formation at rest in normoxia, during hypoxia and especially during exercise, with the most pronounced gradients observed across the femoral circulation. In contrast, there were no gradients consistent with S-nitrosohemoglobin consumption.
Collectively, these findings suggest hypoxia, and to a far greater extent exercise, independently promote arteriovenous delivery gradients of intravascular nitric oxide with deoxyhemoglobin mediated nitrite reduction, identified as the dominant mechanism underlying hypoxic vasodilation. This is as opposed to the competing hypothesis of S-nitrosohemoglobin formation.
In summary, by distinguishing between the two competing mechanisms that underpinned endocrine nitric oxide vasoregulation, that is, the S-nitrosohemoglobin hypothesis versus the nitrite reductase hypothesis, these data help us to understand the dynamic interplay that takes place between nitric oxide metabolites as a function of oxygen demand in vivo, and will help to establish the most specific and sensitive prognostic markers of vascular health and therapeutic interventions that optimize tissue oxygenation.
Dr. Lam: The next study addresses the controversial issues of thrombus aspiration during percutaneous coronary intervention, or PCI, for the treatment of ST elevation myocardial infarction, or STEMI.
Dr. Jolly and colleagues from Hamilton General Hospital in Ontario, Canada performed an individual patient meta-analysis of three eligible large randomized trials that is the TAPAS, TASTE and TOTAL trials including more than eighteen thousand patients who underwent PCI for STEMI. They found that as a routine strategy thrombus aspiration did not reduce cardiovascular mortality for STEMI patients undergoing primary PCI, and that exploratory analysis of patients with high thrombus burden suggested that thrombus aspiration may improve cardiovascular mortality but at the price of an increased risk of stroke or transient ischemic attack.
In summary, these data suggest that thrombus aspiration should not be used as a routine strategy in patients with STEMI, however in patients with high thrombus burden, further large randomized trials are needed to determine if improved forms of thrombus aspiration can reduce cardiovascular mortality and to determine its safety with regards to stroke.
Dr. Lam: The next paper is the first study to look at coronary artery calcium imaging as a tool to personalize systolic blood pressure treatment goals.
Dr. McEvoy and colleagues from Johns Hopkins University School of Medicine in Baltimore, Maryland studied 3,733 participants from the multi-ethnic study of atherosclerosis with systolic blood pressure between 120 to 179 millimeters of mercury. Within subgroups categorized by both systolic blood pressure and estimated ten year atherosclerotic cardiovascular disease risk, they compared multi-variable adjusted hazards ratios for the composite outcome of incident atherosclerotic cardiovascular disease or heart failure after further stratifying by coronary artery calcium.
The authors found that combining coronary artery calcium imaging and assessment of global atherosclerotic cardiovascular disease risk had potential to guide personalized systolic blood pressure goals, particularly among adults with an estimated risk between five to fifteen percent, and pre-hypertension, or mild hypertension.
For example, among those with an atherosclerotic cardiovascular disease risk of less than fifteen percent and who had systolic blood pressure between 140 and 159, those with a coronary artery calcium score up to 100 were at two times the risk, while those with a coronary artery calcium score more than 100 were at 5.7 times the risk of events, all compared to a coronary artery calcium score of zero. Thus, information on coronary artery calcium burden may be considered when making personalized treatment decisions about blood pressure targets, particularly among patients with an estimated cardiovascular risk between five and fifteen percent, and who have either pre-hypertension or mild hypertension.
In summary, information on coronary calcium burden may be considered when making personalized treatment decisions about blood pressure targets, for example, choosing a traditional goal of 140 or a more intensive goal of 120 millimeters of mercury. The authors ended by calling for a precision medicine clinical trial evaluating risk-based blood pressure treatment goals, preferably incorporating coronary artery calcium.
Well, those were your highlights, now for your feature discussion.
Dr. Lam: On today's episode we are going to be discussing the very important issue of type-two myocardial infarction, very important yet usually neglected compared to type-one myocardial infarction. As a reminder to our listeners, type-two MIs are the ones where there is myocardial demand-supply mismatch whereas type one is the usual acute coronary artery plaque rupture and thrombosis. To discuss this I am really honored to have two James' on the podcast. The first is Dr. James Januzzi from Massachusetts General Hospital, the second is Dr. James de Lemos, executive editor of Circulation from UT Southwestern.
Welcome to you both.
Dr. Januzzi: Thank you very much Carolyn, really great to be speaking with you.
Dr. de Lemos: Thanks Carolyn, it's great to be on.
Dr. Lam: Dr. Januzzi, could you please let us know what you found in this paper, it's really extraordinary. Just give us a top line of the results.
Dr. Januzzi: Basically we set out to examine the question of how frequent type-two myocardial infarction is in a population of patients followed longitudinally after they have taken a trip to the cath lab for one reason or another. Really with the goal to better understand the type-two MI syndrome. It was our hypothesis that type-two MI was perhaps more common than people may have recognized, and that type-two MI would be higher risk in terms of the likelihood for ischemic complications than what people had previously recognized. As you point out, type-two MI is often neglected from a management perspective.
What we found, basically, was among a cohort of patients, 1,250 patients coming through the cath lab at the Massachusetts General Hospital Heart Center, in follow up over a several year follow up period with a maximum of eight years of follow up, with a mean of about 3.4, a median of 3.4 years follow up. Out of the 1,251 patients that we enrolled and followed, 152 actually had an incident type-two myocardial infarction during follow up. Additionally, type-two MI was actually quite recurrent in many patients, and in each of the cases whether individual or in most patients with recurrent type-two MI, the mortality risk was really quite striking. Patients that had a type-two MI, partially because they were more complicated medically speaking, as one might have expected, they were older and had lower blood pressure, more coronary disease, heart failure and other medical comorbidities. The likelihood for a major adverse cardiovascular event was more than doubled in patients that suffered an incident type-two MI, the risk for mortality was actually remarkably almost ten-fold higher with a cardiovascular death rate that was around nine-fold higher, heart failure was tripled.
Really just illustrates the very morbid nature of the type-two myocardial infarction, and illustrates the fact that studies are urgently needed to better understand how we should manage these patients.
Dr. Lam: Dr. Januzzi when I manage patients I find this diagnosis of type two-MI to be a very dirty one to make, if you know what I mean. It's hard to really be sure what's happening, and what to attribute rises in troponin to, and so on. Could you tell us a little bit more about how difficult it was to adjudicate the events, and what's the risk of misclassification in your study?
Dr. Januzzi: It's a challenge, and that's something that came up during the peer-review process. We really wanted to make sure that we got this right, so in fact we went back and did a cross-sectional re-review of cases to make sure that our adjudication process was accurate. It's not a very straightforward thing to judge, obviously. A rise and/or fall in troponin may be from a type-one myocardial infarction. There's increasing interest in a syndrome of myocardial injury in the absence of a classical myocardial infarction. Then lastly, we recognized that troponin may rise and fall, for example, in patients with heart failure, possibly due to non-coronary mechanisms. You are correct, it may be a challenge to classify these patients solely on the basis of the presence of a rise or fall of troponin.
What we did was classify them utilizing the Universal Definition of MI Task Force criteria, which includes symptoms and signs, as well as a rise and/or fall of troponin, plus evidence for loss of myocardial function on non-invasive testing. We were pretty strict, actually, in terms of how we judged them, and when we went back and re-reviewed ten percent of the cases, we actually found that all of the fifteen cases that we went back and re-reviewed met the criteria that we had articulated in the front end. We feel pretty confident that we got the diagnosis correct, but obviously it's a challenge in every day practices, as you rightfully point out.
Dr. Lam: It does certainly sound very rigorous, indeed. Dr. de Lemos, you managed this. He mentioned reviewers giving him a hard time, what was it like managing this paper?
Dr. de Lemos: It was fascinating because the Universal Definition that introduced type-two MI into the classification scheme is only a decade old. It's remarkable how little we know about the problem, and how much we struggle in clinical practice. We thought this paper was one of the first and most comprehensive evaluations to put some construct around the problem. As you pointed out, Carolyn, it is a messy diagnosis. Even when you do it in an organized, researched fashion this reflects what we all deal with in clinical practice where it's not so easy to define myocardial infarction even when given the criteria of the Universal Definition. The challenge really is that only a minority of the troponin elevations that are the classic type-one MIs that we know what to do with. The rest of them are either these troponin elevations NOS, type-two MI, or something on a continuum on this spectrum that's really hard to differentiate.
This paper's important because it really highlights that these non-type-one MIs whatever they are, are common and associated with really high risk, and it's sort of a call to arm that we better start to understand and sub-classify these if we're going to be able to reduce risk in this very high risk population. That's really why we were so interested in the paper, and why we worked so closely with Jim and his team to address some of the issues that you just raised.
Dr. Lam: I completely agree, in fact it's beginning to remind me of the world of HFpEF when we first started realizing that people with heart failure, even though ejection fraction's normal are definitely not doing well. James Januzzi, if you don't mind, what do you think are the implications for treatment, what are the things that you think need to be examined going forward?
Dr. Januzzi: Carolyn I laughed when you mentioned HFpEF because at one of the recent Universal Definition of MI Task Force meetings, I actually said that type-two MI is the HFpEF of the myocardial infarction world. To answer your question, I have approached this question very much the way we do in the heart failure space relative to heart failure with preserved EF. In order to develop a strategy for treatment for type-two MI, we need considerable advances still in our understanding of just what exactly is a type-two MI, what types of patients have type-two MI, and on an individual level, the treatment strategies may follow.
The problem here is if you look just at all comers who suffered a type-two MI in our study, the majority were actually taking statins, they were taking aspirin, they were more likely to be taking beta-blockers. So the patients themselves were actually on the very treatments that we might think about prescribing in those folks that have a type -wo MI, and yet they still suffered the MI, and they had worse outcomes. One might think about coronary disease and revascularization, and indeed one of the nice things about our study is we enrolled patients at the time of coronary angiography, and then followed them subsequently, so we actually had detailed coronary angiograms on every one. Those suffering an incident type-two MI certainly had more coronary disease, so one might argue revascularization might either be protective if done prior to the onset of type-two MI, or at the time of type-two MI a revascularization-driven strategy might be a logical approach.
I think more fundamentally, bringing it back to heart failure and to the HFpEF analogy, I think that in order to better understand treatment we need to better understand just who these patients really are. So much like has been done in the heart failure space we're now doing cluster phenotype analyses where we're looking at the various phenotypes of patients with type-two MI using network analyses, which is one way to approach a problem when you've got a mix of various diseases that fall under the same title. So in those patients with preserved ejection fraction heart failure, there are patients that are younger obese patients, there are the patients with advanced diabetes, et cetera.
Our hypothesis for our present research is to examine this question within the type-two MI diagnosis to see if we can identify specific clusters of phenotypes that might be treated in specific ways. The coronary patients might deserve revascularization, the heart failure patients might deserve a different approach for their care. That, I think, might be the way forward, exactly taking a page from the playbook that you just mentioned with respect to preserved ejection fraction heart failure.
Dr. Lam: Wow, how terribly exciting. Congratulations again for this paper, I really think it's a landmark and will open the door to many more important papers. I would like to switch tracks a little bit at the moment. We are coming to six months into the new Circulation editors that have been under the leadership of Joe Hill and James de Lemos, and I'd actually like to start by asking you, Dr. Januzzi, what was it like working with our new Circulation team? Then handing the mic over to Dr. de Lemos to tell us a little bit more about what the journey has been so far in the last six months.
Dr. Januzzi: Thanks for asking, it was an absolute pleasure. I trained with Dr. Hill and with Dr. de Lemos in one degree or another during all of our respective residency and/or fellowship training, so I've known these guys for a long long time. I think that the most important aspect in the peer review process is a collaborative and collegial process where the division between author and editor can allow for communication. In this experience with this manuscript, it was a very easy-going and collaborative process where the paper from beginning to end grew in its quality, and ultimately landed in the journal, and the way that it did was, I think, a substantial likelihood for heavy citation. That says a lot about the editors who really help us to bring it to this final product.
Dr. Lam: Dr. de Lemos?
Dr. de Lemos: We're now six months in to the new Circulation editor team's tenure, and I think all of us are having a blast. I think we've put together this team of diverse international experts that build off each other and thrive off each other, so from the team perspective, we're just having great fun, working hard, learning a great deal. We hope that those of you out there that are listening and reading, and submitting papers, and using our journal for your own research, are noticing the changes that we've made and think we're headed in the right direction. We'd love to hear from you about the things you like, and those things you don't like. We do think we've, in many ways, modestly changed the focus of the journal. There's so many new content categories that are designed to speak to the global burden of cardiovascular disease, the international aspect of cardiovascular research, and new clinically relevant problems, translating basic science so that clinicians can understand it. We hope that clinically active, as well as basic investigators are finding these changes useful in their own daily lives.
Dr. Lam: Thank you both so much for spending time with me on Circulation on the Run. Thank you everyone, don't forget to tune in next week.