Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and it's editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
Can we get better at predicting clinical benefit of PCSK9 inhibition based on the severity and extent of coronary artery disease? Well coming right up after these summaries we have an important discussion of an analysis from the FOURIER trial, so stay tuned.
The first original paper this week suggests that targeting visceral adiposity may be the crucial step to limit age-related cardiac remodeling and to promote healthy cardiac aging. Co-first authors Drs Sawaki and Czibik, corresponding author Dr Derumeaux, from INSERM France, and their colleagues, hypothesize that since aging induces cardiac structural and functional changes, linked to increase deposition of extracellular matrix proteins including osteopontin, well osteopontin may play a role in myocardial aging.
To test this hypothesis, they studied osteopontin-deficient mice and their wild-type litter mates at two and 14 months of age in terms of cardiac structure, function, histology and key molecular markers. They found that during aging, visceral adipose tissue represented the main source of ostepontin and altered heart structure and function via its profibrotic secretome. Furthermore, interventions targeting osteopontin, such as visceral adipose tissue removal and osteopontin deficiency, rescued the heart and induced a selective modulation of fibroblast senescence. This work uncovers ostepontin's role in the context of myocardial aging and suggests that osteopontin may be a potential new therapeutic target for a healthy cardiac aging.
The next study shows that higher triglyceride rich lipoprotein cholesterol may be a risk factor for cardiovascular disease and potential therapeutic target. First author Dr Vallejo-Vaz, corresponding author Dr Ray from Imperial College London, and their colleagues assess the relationship between triglyceride-rich lipoprotein cholesterol and cardiovascular risk and whether this risk was modifiable among patients receiving statins in the TNT trial. They found that higher levels of triglyceride rich lipoprotein cholesterol were associated with a significantly higher rate of cardiovascular events among coronary patients treated with statins. Statin therapy reduced triglyceride-rich lipoprotein cholesterol and to a greater extent among those treated with a higher statin dose.
Based on their post hoc analysis of the TNT trial, they found that more intensive statin therapy with atorvastatin 80 milligrams, compared to atorvastatin 10 milligrams, resulted in a significantly greater cardiovascular risk reduction among patients with higher triglyceride-rich lipoprotein cholesterol. These results were consistent for higher triglycerides and directionally concordant for non-HDL cholesterol. A higher percentage reduction in triglyceride-rich lipoprotein cholesterol was associated with lower cardiovascular risk independent of LDL cholesterol reduction. Thus, these findings suggest that triglyceride-rich lipoprotein cholesterol is not only a cardiovascular risk marker, but also potentially a therapeutic target.
Late gadolinium enhancement on cardiac magnetic resonance imaging represents fibrosis and is seen in 60% of adult patients with hypertrophic cardiomyopathy. However, what about in children and adolescents with hypertrophic cardiomyopathy? First author Dr Raja from University of Copenhagen in Denmark, corresponding author Dr Ho from Brigham and Women's Hospital in Boston, and their colleagues looked at cardiac magnetic imaging data from 195 children and adolescents with hypertrophic cardiomyopathy. Late gadolinium enhancement was present in 46% of patients with overt hypertrophy as opposed to 60% typically represented in an adult population of hypertrophic cardiomyopathy. On the other hand, late gadolinium enhancement was not seen in mutation carriers without left ventricular hypertrophy.
In patients who underwent serial imaging, increases in late gadolinium enhancement, left ventricular mass, and left atrial size were detected over two and a half years. Thus these findings in children provide additional insights into the biology and natural history of hypertrophic cardiomyopathy and confirmed that fibrosis is a significant part of the disease process in both children and adults.
Whether the adult mammalian heart harbors cardiac stem cells for the regeneration of cardiomyocytes is an important yet contentious topic in the field of cardiovascular regeneration. This week's paper adds to the growing knowledge in this area. First author Dr Li, corresponding author Dr Zhou from Chinese Academy of Sciences and their colleagues developed a new genetic lineage tracing system to label all nonmyocyte populations that contain putative cardiac stem cells. Using dual lineage tracing system, they assessed if non-myocytes generated any new myocytes during embryonic development, adult homeostasis and after myocardial infarction. Skeletal muscles were also examined after injury and acted as internal controls.
By using this stem cell marker free and dual recombinases mediated cell tracking approach, the author showed that new myocytes arose from nonmyocytes in the embryonic heart, but not in the adult heart during homeostasis or after myocardial infarction. As positive controls, the same lineage tracing system detected new myocytes derived from nonmyocytes in the skeletal muscle after injury. Thus, this study provides in vivo genetic evidence for non-myocyte to myocyte conversion in the embryonic but not the adult heart. This study also provides a new genetic strategy to identify endogenous stem cells, if any, in other organ systems for tissue repair and regeneration.
Well, that wraps it up for our summaries this week, now for our feature discussion.
Are there subsets of patients that derive greater clinical risk reduction with the PCSK9 inhibitors? Well we're gonna find out about that right now with a discussion of our feature paper entitled the “Clinical Benefit of Evolocumab by Severity and Extent of Coronary Artery Disease.” So pleased to have with us Dr Marc Sabatine from the TIMI Study Group, who is the first and corresponding author of today's feature paper, as well as our editorialist, Dr Roger Blumenthal from Johns Hopkins University. And of course, we have a familiar voice, a very important editor of our digital strategies and that's Dr Amit Khera from UT Southwestern.
Welcome everyone, I think I'd really like to start with maybe asking Roger to paint the background of the importance of this paper. Simply because I just love the title of your editorial, which is “Realizing the Value of PCSK9 Inhibitors: Are We Closer to Finding the Sweet Spot?” I think that really encapsulates it. So Roger, your thoughts?
Dr Roger Blumenthal: As Amit Khera knows, I'm a golfer, so when you think about the sweet spot on the club, and we know that PCSK9 inhibitors are a great story of translation from bench to bedside, and we also know that the high cost of the therapy presents a challenge. So what Dr Sabatine and colleagues did was to try to identify the sweet spot for its most effective use and that was a pleasure to comment on Dr Sabatine's excellent study.
Dr Marc Sabatine: I think taking a step back I would say from pure biologic perspective, we know that lowering LDL cholesterol will reduce events and that's true and primary and secondary prevention and so if you have therapies that were safe and inexpensive, then I think you wouldn't need to really look for that sweet spot cause it would be all sweet if you will to extend the analogy. But Roger's absolutely right that when you have therapies that are then expensive, then you have to decide, okay in which patients will I get the biggest bang for my buck? And that's a very legitimate question to ask.
And so in FOURIER, overall the trial was positive but as we look for subgroups we say, "Can we find individuals who enjoy a greater absolute risk reduction?" Because therefore the benefit cost ratio is gonna be particularly favorable. And so we approach that in a couple different ways. First you can look for just predictors of baseline risk, so if someone has twice the baseline risk and the same relative risk reduction, you should get about twice the absolute risk reduction and therefore the number needed to treat would be cut in half. And so based on our experience from other TIMI trials and other datasets, we looked at three features that have identified patients with higher baseline risks.
Amongst those with a history of MI which is in and of itself a heterogeneous group. And so those features were patients with a more recent MI, those with multiple prior MIs and those with known residual multivessel coronary disease. And all three features in the FOURIER dataset, not surprisingly, were predictors of risk with patients having an average about a 50% higher baseline risk. But what was particularly nice was that the subgroups also identified patients who had greater relative risk reduction. And so when you couple the two, the higher baseline risk with the greater relative risk reduction, that translated into greater absolute risk reduction then in each of these high-risk groups, the absolute risk reductions over three years or for CV death, MI, and stroke was around 3% versus around 1% for the low-risk groups.
And so that changes the number needed to treat by a factor of three.
Dr Carolyn Lam: Wow, that's so cool. Amit, do you think you could just give us a sneak peek into the editors’ discussions when you saw this paper?
Dr Amit Khera: This was an easy one, it's clearly a very important paper and if you step back 10,000-foot view, these drugs were initially approved based on LDL lowering and people were using them without knowledge of whether or not they actually lowered events. Marc's group and others have now shown us that certainly they do lower events, but really the next most important thing is application. Who should we use them in and when should they be used and where might they be most effective and I think it was said out in the introduction of this paper, this idea of personalized medicine. And I think this really is an important step forward, not just for PCSK9 field but in general, how we should be thinking about drugs, about balancing cost and benefits and who would benefit most.
So maybe one analogy, I think PCSK9 was not prescribed as much as they had been predicted given costs and other considerations and maybe with analysis like this they've hit it out of the rough back on the fairway, I threw that in for you, Roger. And I do have one question for Marc, which is this is clearly important to better define who would benefit the most and I guess in terms of action abilities, the goal here to provide guidance for clinicians where, you know, if I'm seeing a patient this morning I would take this into account or is this something larger where we recently saw with alirocumab, they changed pricing based on sub-group analysis of a higher risk group. How do you think we should move forward with this type of information?
Dr Marc Sabatine: I’ll get back to the point I raised earlier, I do want to underscore that I think that the true biologic notion is that all these patients, sub-types of secondary prevention or primary prevention all benefit from LDL lowering. So I wouldn't want people to walk out with the notion that it's the only subset that would benefit and really from a population level, obviously Roger's in a better position to speak about this, but sort of shifting the population LDL lower in general would have a huge impact on the risk for cardiovascular disease. But to your question Amit, looking in for a patient in front of you, I think it's quite fair to say right now there's this kind of tug of war back and forth between payers and clinicians.
Clinicians saying, "I have a patient in front of me, they have known atherosclerotic cardiovascular disease, I wanna lower their risk, I wanna manage their risk factors and I wanna get their LDL cholesterol lower and I have a bunch of great tools in front of me." Statin for sure is the foundation, maybe acetamide and PCSK9 inhibitors. And then payers saying, "Well wait a minute, these are expensive drugs and so we're gonna try to restrict that and create a lot of hoops for clinicians to jump through." And so I would rather than wasting all that time back and forth, I think it is logical to say, "What are the high-risk groups?" Where we can agree there's the large enough absolute risk reduction that for a given cost, that makes sense.
Allow there to be alignment for that and have clinicians just be able to write a script and have it filled rather than wasting a lot of time with preauthorization and letters back and forth.
Dr Amit Khera: That's a great point, maybe I'll just take one follow-up, which is now trying to sift through all the high-risk groups and they end up maybe becoming a bit of a Venn diagram. I know in Roger's editorial he talked about the other FOURIER analysis with PAD and there's more groups to come or do we have enough of a starting place where we think we have enough for decision making?
Dr Marc Sabatine: I would say there are a variety of groups, there is some overlapping even in the paper then we looked at the union of those three high-risk features, which identified about two thirds of the patients who were enrolled in the trial with a history of MI. But you're right, the other slices of the data that will also identify high risk groups, PAD is a particularly good one because most of the therapy for those patients has focused on antithrombotic therapy, which always will have some downside for increased bleeding, whereas risk factor modification in this case has no downside. So that's a very high-risk group, it certainly is important to focus on. But I think within the MI subset, this is a great place to start the other analyses we're doing.
And probably after we've sort of finished the series of, if you will, these kind of univariant slices, then we'll try to put that together into a more comprehensive picture.
Dr Roger Blumenthal: We tried to say that we still need the formal cost-effective analyses in these specific high-risk groups, but it seems most reasonable to focus on engaging in shared decision making now with our patients about PCSK9 inhibitor use and those with a recent ACS and the basis of Odyssey Outcomes and we're awaiting the final publication of that. Symptomatic peripheral arterial disease, which Marc previously published in Circulation, and then looking at these high-risk features that was the subject of this article, those with a more recent MI within the past two years, multiple prior MIs and residual multivessel coronary disease.
And one of the things that we especially found interesting was among the more than 8,000 individuals without a high-risk feature, the event rates were nearly unchanged in the evolocumab versus placebo groups. So I think that's very important, but one other point that we have to keep in mind is that the focus of the last set of guidelines and probably the next cholesterol guidelines that likely will be out in November, will have a large component of the shared decision making and we need to see where the cost comes down, whether these companies that make these medications will be able to significantly lower the cost in a reproduceable manner and patients and clinicians will have to jointly decide what to do, do we add acetamide? Do we add a PCSK9 inhibitor?
But we finished our editorial saying that all clinicians and patients should currently pursue a comprehensive lifestyle and medical regimen for secondary prevention. We all have to remember that and if a person's LDL, a high-risk individual is at least 70 with high-risk features and certainly above 100 on maximum tolerated statin therapy, it's important to strongly consider a PCSK9 inhibition and it'll be very interesting to see what the final wording is when the ACC/AHA cholesterol guidelines come out in November.
Dr Carolyn Lam: Amit, would you like to add any further take-home for the clinicians listening in?
Dr Amit Khera: I just first want to congratulate both of these discussions today, I think the paper was so incredibly important and I think Roger's group really helped frame it well in the field. The one thing I'd say is this is a moving target, we have some early guidance now that I do think is actionable, so I actually have clinic in about an hour and I'm sure I'll be thinking about this as I think about how to apply PCSK9. Which groups might benefit most, so I do think this is actionable now, I think the points that were made about cost effective analysis, how do we bundle all these concepts or high risk patients into maybe an algorithm and how do the guidelines interpret this as a moving target. We'll wait to see, but I do think there's some important actionable information even now for our clinical patients.
Dr Carolyn Lam: I just love that, and you know that is just so much in line with the ethos of what Circulation is about now. We really, really love the papers that you have to pick up because they're of immediate applicability to your clinical practice.
Well audience, you heard it right here. Thank you so much for joining us this week and of course don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore. I'm the one you usually hear chatting about all the papers in your weekly issue, however I am so delighted to be handing over the mic this week to two beloved colleagues, and they are Dr Greg Hundley and Dr Vlad Zaha, who will be taking us through this week's very special issue centered around cardio-oncology. Here they are.
Dr Greg Hundley: My name is Greg Hundley. I'm a professor at VCU Health Sciences in Richmond, Virginia. We also have Vlad Zaha, who is an assistant professor at University of Texas Southwestern in Dallas.
Dr Vlad Zaha: Hello, everybody.
Dr Greg Hundley: We're going to be talking about the field of cardio-oncology today. As we all know, there have been many advances in the treatment of cancer lately, such that cancer is now becoming in some regards almost a manageable disease or a chronic disease for many individuals. But unfortunately we're seeing the emergence of cardiovascular disease in many patients, so much so that for some cancers, for example breast cancer survivors, cardiovascular events have supplanted the occurrence of cancer-related morbidity and mortality overall.
And so emerging today is this new field of cardio-oncology, which is really a bridging discipline between oncologists and cardiologists that have been focused almost on examining the relationship between chemotherapies, radiation therapies, newer targeted immunologic therapies on the development of cardiovascular events. We as cardiovascular medicine specialists often become involved and then we are consulted to see a patient that might be scheduled to receive a cardiotoxic therapy and what should we do. Maybe they've already received, they're in the middle of the therapy, and we're asked to provide guidance to help the patient move through that therapy successfully.
We're examining survivors now, those that have gone on the therapy and are experiencing increased cardiovascular risk. And then finally, a new emerging field that examines the association of risk factors that seem to be common between cancer and cardiovascular disease.
In this issue of Circulation there are theories, really a miniseries of manuscripts, that are at this interface between cardiovascular and oncologic science and medicine. Following a similar miniseries that we published in 2015, this new block of manuscripts looks on some of the risk factors and mechanisms that may be common between these disorders.
We're going to start today and look at this particular issue and examine the original manuscripts, look at the letters, and then talk a little bit about the review articles. I will walk through some of the introduction and then Vlad Zaha, who is working in cardio-oncology at University of Texas Southwestern, will help interpret for us some of the results and the meaning.
The first study, an original manuscript by Simes et. al that's a subanalysis of the lipid study, and that's the Long-Term Intervention with Pravastatin in Ischemic Disease. The study is going to examine the relationship between D-dimer and the future development of cardiovascular events, but also importantly, cancer-related events. Remember, D-dimer is the degradation product of cross-linked fibrin markers of hypercoagulation and thrombosis. We use this a lot in the emergency department as an identifier of those at risk when we're suspecting one of CVT, pulmonary emboli, etc.
This particular study focused on individuals aged 31 to 75 years that had experienced previously a myocardial infarction. The patients were randomized to receive 40 mg of pravastatin versus a placebo and as part of the study they were followed for six years to identify cardiovascular events. But at the end of the study another examination, an extended review, was enabled so that the patients or participants could be followed for another ten more years and in addition to looking at cardiovascular events, they also looked at all-cause mortality and etiologies of that mortality and specifically cancer.
Vlad, can you tell us a little bit about some of the results and what did D-dimer predict?
Dr Vlad Zaha: D-dimer has been considered a rather non-specific product that was first introduced in clinical practice in the 1970s for diagnosis of venous thromboembolisms. It is really interesting in this study that the others identified D-dimer that it is an independent predictor of not only long-term risk of arterial and venous events but all-cause mortality, cardiovascular disease mortality, cancer incidents and mortality and non-cardiovascular disease and non-cancer morality.
It raises interesting questions that are further explored in an editorial in the same issue about what is a low and what is a high D-dimer and also what drives the D-dimer generation in these patients.
Dr Greg Hundley: And so, it's interesting as well that one is identifying those at risk of cardiovascular disease but also cancer. Do the authors and the editorialists speculate on what that connection may be?
Dr Vlad Zaha: The question that is discussed is a common area of etiology that is being more and more discussed nowadays as bridging the domains of heart disease and cancer, and that is information. Information resulting then in alteration of the clotting cascade and hypercoagulability that may then influence downstream both atherosclerosis and cancer processes.
Dr Greg Hundley: Very good. It's interesting that we're bringing up this whole area of thrombosis because that really follows in the next study, which is a large population cohort assessment that is collected from a Danish registry of 6600 subjects that had experienced a lower extremity arterial, not venous, but arterial thrombosis. In that study what did they uncover, Vlad, in terms of an association with cancer and previously experiencing a lower extremity arterial thrombosis?
Dr Vlad Zaha: Another interesting study where the patients uncovered an increased risk of cancer compared to the general population, especially during the first six months before, the investigators identified an association between lower limb arterial thrombosis and increased all-cause mortality in common especially for the smoking-related cancers. This is a very interesting study that brings up the possibility of opportunistic screening, again focused on cancer-related signs and symptoms during the diagnostic workup for lower limb arterial thrombosis.
Dr Greg Hundley: And so, in these first two studies, both large in number, were identifying issues related to thromboembolic events and cardiovascular disease that also appear related or associated with the future development of cancer. The next couple of studies now switch and address issues related to mechanism. The first is a relatively large complex translational study by Meijers and associates that were examining the relationships between heart and vascular injury and the future development of colon cancer.
In this particular study there were two separate experiments, one group performed in mice and the other performed in analyses of serum and plasma that were collected from human subjects that had experienced colon cancer. In the first series of experiments in mice, the mice were induced myocardial infarction and then they were a strain that were somewhat predisposed to development of colon cancer. What the investigators did is they examined in this strain predisposed to the development of colon cancer, the impact of inducing a myocardial infarction and promoting heart failure versus those that were not and they identified what looks to be some sort of association between an increased risk of development of colon cancer.
Vlad, what were your observations and thoughts in terms of these particular findings and results?
Dr Vlad Zaha: This is an interesting paradigm of bringing basic science observations and testing them in a translational fashion. It is a combination of really elegant studies in a mouse model that identifies potential targets of clinical relevance in a model of myocardial infarction. The authors evaluate the fact that such molecules in human cell line models and test the proliferation in that environment. The question is then: How does this reflect in a cohort of patients? That, I think, is really the strength of the study to be able to show that some of the biomarkers identified which events can have an implication at the bedside.
Dr Greg Hundley: It was really interesting in that in the animals, independent of the hemodynamic compromise, so the hypotension, the reductions in EF, these circulating biomarkers that you identified seemed more associated with the development of colon cancer and then in the human study, examining similar factors were observed in patients with colon cancer and heart failure from the circulating blood of those individuals. Very interesting relationship identified in a very elegant translational study that involved both animal models and human subjects.
The second mechanistic paper is by Li and associates and it's really addressing the issue of anthracycline-related cardiovascular injury. Remember, we still utilize anthracycline chemotherapy today as a fundamental curative component of the therapeutic regimen for lymphoma, leukemia and sarcoma, also in those with triple-negative breast cancer as an important component of that regimen for adjuvant treatment. In this particular study, the investigators were examining the implication of phosphoinositide 3-kinase. That is an important enzymatic regulator of tumorigenesis, but it also when it's expressed is up-regulated during cardiac stress and really impacts adverse remodeling and promotion of heart failure.
In this particular study, the investigators in a mouse model were looking at blocking this particular enzyme and they had some really interesting results pertaining to the development of heart failure and cancer. Vlad, what did you see in this study that looked unique in that perspective?
Dr Vlad Zaha: This is an especially interesting study for the perspective of the oncologists who still have to prescribe anthracycline, given the uncertainty of early toxicity that can manifest in some studies in five to ten percent of patients. Also, related to the late toxicity of anthracycline treatment in survivors of childhood cancer. What is particularly interesting about this isoform of phosphoinositide 3-kinase, the gamma isoforms, is that at the same time blocking this enzyme in macrophages increases the anti-tumor, I think it's the anthracycline therapy, and blocking it in the cardiomyocytes, suggests a potential cardioprotective mechanism.
Having a target that can be used both to enhance the anti-cancer effect of anthracycline and to enhance the cardioprotective mechanism is really a potential ideal intervention that would help maximize the anti-cancer treatment and at the same time protect the heart.
Dr Greg Hundley: Fantastic. Again, new research helping to come up with ways for those that continue to need anthracycline therapy that we may be able to attenuate some of the untoward cardiovascular effects, all the while preserving the antagonistic features associated with the treatment for cancer.
Let's switch to the other sort of prospective original research format that we have in Circulation, and that's our letter format. Remember, our letters are addressing a specific point that can be readily appreciated in 800 words or less. The first is a letter by Anquetil et al that examines individuals recorded in the VigiBase World Health Organization database. This is basically a database organized around treatment of cancer and cancer therapeutics and it is examining those individuals that received sort of a newer class of agents called immune checkpoint inhibitors. Remember, that is modulation of our immune system to help attack cancer.
In some rare circumstances, relatively infrequent, when these agents have been administered, the immune system has been unlocked and attacks the heart, promoting a myocarditis that if not recognized can be fulminant and lead to death. This particular group identified a new phenomenon that we need to be aware of and that's just frank myositis.
Vlad, what are your thoughts on now perhaps these agents being associated with the development of myositis in the skeletal muscle?
Dr Vlad Zaha: Often when adverse events, as you mentioned Greg, are an important concern for these new powerful tools for the oncologists and it has been pretty early in the process where some of the cases have demonstrated severe cardiovascular events. Fortunately it is a very low percentage, less than 1% of cases that can manifest with fulminant myocarditis, but this raises again a question of expanding the view towards other systems when we are applying one of these early novel molecular interventions.
In this context, the recognition of myositis in another small percentage of patients is an important observation and increasing awareness of both cardiologists and oncologists towards this side effect is important as not all fatigue is equal and sometimes that can be due to manifestations of cardiomyopathy and sometimes it can be a manifestation of oxygen extraction in the peripheral tissue than muscle contractility. It is an important hypothesis-generating piece that will allow people to appreciate more of the complexity of addressing the intrinsic molecular mechanisms in cancer and heart disease.
Dr Greg Hundley: It sounds that we need to be aware of another potential etiology of fatigue to put in an armamentarium of differential diagnoses for those patients that are not getting quite back to where they were from an exercise and activity level after treatment. The second research letter focuses on individuals that are receiving a Fontan procedure. Remember, Fontan procedures are surgical corrections for those primarily with single ventricles where we're diverting caval blood to the pulmonary circulation, since in some situations there's really no functional right ventricle. These patients over time experience chronic venous hypertension and have associations with liver disease.
In this particular research letter, the authors are examining the relationship between really for the first report in an aggregate form of the relationship between undergoing a Fontan procedure and the development of hepatocellular carcinoma. Vlad, any quick comments to highlight on this particular procedure? I thought something that was interesting is that these individuals experienced these hepatocellular carcinomas in their 20s and 30s.
Dr Vlad Zaha: That's right, Greg. This study confirms observations from previous case reports and the early occurrence of hepatocellular carcinoma is raising still important hypotheses for future clinical trials. On one hand, either there is an increased risk of hepatocellular carcinoma development in patients with non-cirrhotic livers after a Fontan operation, or the current screening modalities using imaging are insufficiently sensitive to identify early signs of cirrhosis in such patients and this stratifies them effectively at an early stage in their disease post-op Fontan procedure.
Dr Greg Hundley: Lastly, let's just briefly discuss here, Vlad, some of the other editorials and review article formats that we have in Circulation. A particular one, a perspective that was written by Peter Libby and Ebert and associates that highlights this phenomenon potentially implicating inflammation and the link between cancer and atherosclerotic cardiovascular disease. The topic of this perspective is really on something called CHIP, which stands for clonal hematopoiesis of indeterminate potential.
What is this CHIP? As we age, basically what happens is we accumulate mutations of hematopoiesis stem cells in our bone marrow. Over time these little clones, they actually have within our bone marrow some survival advantages and they can spill out into the blood and actually can be associated with future leukemias. Those that have a large population of this particular clonal progeny, these CHIP-type cells, they have an increased risk of developing cancer, but also the levels of these are associated with increased overall mortality and it appears some risk of cardiovascular disease. How could that be? One characteristic of this particular cell line is they are associated with dysregulation of inflammatory genes that go on to produce, are associated with other inflammatory mediators.
Vlad, this is calling in question and helping us to examine the relationship between inflammation, cancer and cardiovascular disease. What are your thoughts here about these very important insights provided by Libby and Ebert?
Dr Vlad Zaha: This is a fascinating perspective, Greg. It really brings, again, in the offline novel molecular mechanisms that have been discovered recently and that are becoming a turning point into the molecular interventions, not only in cancer but potentially soon in cardiovascular disease prevention and treatment. Having a common root for a problem set involving such a prevalent cardiovascular problem as atherosclerosis and cancers reveals the connection between the different systems and the fact that integrating our understanding of the molecular regulation of cell proliferation results in an effective translation of leading to new targets and new approaches to treat disease.
It is striking that there are multiple areas where cancer and inflammation are interacting, one of them being at the cellular level and other ones at humoral levels, in a way reproducing other complex mechanisms that we see in regulation of inter-system interactions within the body.
Dr Greg Hundley: And so, summarizing this entire issue in Circulation, what a wonderful collection of a series of original manuscripts, both in the extended and the letter format as well as review articles, including a primer by Handy and associates that evaluates or draws attention to our screening tools that how we might examine the relationship between cardiology and the whole world or hematologic oncology related issues. And then this very unique perspective by Peter Libby and really is a continuation of the growth of this, as we called earlier, the bridging discipline of cardiovascular medicine and oncology as we work toward improving survivorship of all individuals with cardiovascular disease and cancer.
I want to thank you for the opportunity to be with you today and encourage you to follow these issues further with the journal. I'll turn this over to Vlad for any closing remarks.
Dr Vlad Zaha: Thank you, Greg. This has been a really exciting overview of important points that are emerging now at this nexus between cardiology and oncology that give us a broader view of the complex interactions that the future will materialize for us, emerging from a molecular intervention on cancer, heart disease, immunologic disease and probably metabolic endocrinology disease.
Thank you for listening.
Dr Carolyn Lam: Thank you so much, Vlad and Greg. This is a tremendous issue and I'm sure, audience, you will be reaching for it right now, I would.
Please let all your colleagues know about this podcast and tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
Can proteomic biomarkers distinguish between subtypes of aortic stenosis even years before surgery? Well, to find out more, stay tuned. That's coming right up after these summaries.
The first original paper this week adds to the evidence that smoke-free policies are associated with a lower risk of cardiovascular disease. First and corresponding author, Dr Mayne from Northwestern University Feinberg School of Medicine, and her colleagues linked smoke-free policies to participants of the Coronary Artery Risk Development in Young Adults, or CARDIA study, which has a follow-up of up to 20 years. They found that smoke-free policies in workplaces were associated with significantly lower risk of incident cardiovascular disease after controlling for a wide range of covariants. Results were weaker for bar and restaurant bans, but in the same direction.
Preventive fractions range from an impressive 24 to 46%. Thus, smoke-free policies may improve cardiovascular health through reducing population exposure to tobacco smoke. However, we should remember that much of the US population remains unprotected by smoke-free policies. Thus, taken together with prior ecological work, these results support the continued expansion of smoke-free policies in indoor public places.
Most phase-3 randomized control trials feature time-to-first event end points for their primary analysis. In chronic diseases, however, a clinical event can occur more than once and recurrent event methods have been proposed to more fully capture the disease burden, as well as to improve statistical precision and power.
However, is this really the case? This question was examined by first author, Dr Brian Claggett, corresponding author, Dr Scott Solomon, from Brigham Women's Hospital in Boston, Massachusetts, and their colleagues, who sought to better characterize factors that influence the statistical properties of recurrent events and time-to-first event methods in the evaluation of randomized therapy.
They performed repeated simulated trials with 1:1 randomization of 4000 patients to active versus control therapy. Through simulation, they varied the degree of between-patient heterogeneity of risk as well as the extent of treatment discontinuation. They then compared their findings with those from the actual randomized control trials.
The authors found that the statistical power of both recurrent events and time-t- first event methods were reduced by increasing heterogeneity of patient risk, a parameter that's not usually included in conventional power and sample size formulae. Furthermore, data from real clinical trials were consistent with the simulation studies, confirming that the greatest statistical gains from the use of recurrent events methods occurred in the presence of high patient heterogeneity and low rates of study drug discontinuation.
The next paper uncovers a novel biomarker and therapeutic target of pulmonary arterial hypertension, and that is selenoprotein P. First author Dr Kikuchi, corresponding author, Dr Shimokawa, from Takaoka University Graduate School of Medicine in Japan and their colleagues performed micro-array analyses using pulmonary arterial hypertension, pulmonary artery smooth muscle cells, and found a 32-fold up regulation of selenoprotein P compared with controls.
Selenoprotein P promotes cell proliferation and apoptosis through increased oxidative stress and mitochondrial dysfunction. Using five strains of genetically modified mice, the authors demonstrated a pathogenic role of selenoprotein P in the development of hypoxia-induced pulmonary hypertension.
Furthermore, sanguinarine, which is an orally active small molecule identified by throughput screening reduced selenoprotein P expression and pulmonary arterial smooth muscle cell proliferation and ameliorated pulmonary hypertension.
In summary, this study shows that selenoprotein P plays a crucial role in the pathogenesis of pulmonary arterial hypertension and may be a useful and novel biomarker and therapeutic target in this disorder.
Familial hypercholesterolemia is known to be associated with a high risk of ischemic heart disease, including myocardial infraction, but what about the risk of ischemic stroke? Well, first author, Dr Beheshti, corresponding author, Dr Nordestgaard, from Copenhagen University Hospital and their colleagues examined the associations of familial hypercholesterolemia and high LDL cholesterol with ischemic stroke in both causal, genetic, and observational analyses using more than 106000 individuals from the Copenhagen General Population Study, and more than 10000 individuals from the Copenhagen City Heart Study.
They used a Mendelian randomization design to test whether high LDL per se had a causal effect on ischemic stroke risk using a combination of the familial hypercholesterolemia causative mutations and common genetic variants associated with high LDL.
The authors found that there was no association between familial hypercholesterolemia mutations and ischemic stroke risk. In the Mendelian randomization analysis, also including common genetic variants, there was also no causal effect of high LDL on the risk of ischemic stroke.
These findings imply that the predominant goal of targeting LDL lowering in those with and without familiar hypercholesterolemia is likely to reduce myocardial infractions, rather than ischemic stroke. Well, that wraps it up for our summaries. Now for our feature discussion.
Circulation publishes numerous papers regarding circulating biomarkers. We talk about biomarkers in the diagnostic, prognostic sense, but what about in a pathophysiologic sense, and especially in a disease as important as aortic stenosis? Well, that's what our featured paper this week is all about and I'm so excited to have with us corresponding author, Dr Stefan Söderberg, from Umeå University in Sweden, as well as our associate editor, Dr Peipei Ping from UCLA. We will be discussing the paper entitled “Proteomic Biomarkers for Incident Aortic Stenosis Requiring Valvular Replacement.” Stefan, could you tell us a bit about what made you look at this very interesting question, and perhaps the unique resources you had in Sweden to look at this?
Dr Stefan Söderberg: I'm a practicing cardiologist, and I have been working a lot with aortic stenosis over the years. It's frustrating that we can't do anything to stop the process. In many cases, the patients are old and frail, and if you could find the means to stop the process long before they need surgery, it will be of great benefit for the human and for the society.
Also, knowing that the interventions on the statins, for example, have been unsuccessful, we thought that there must be better ways or other biomarkers. Furthermore, that many of these studies, the phenotype of aortic stenosis has been very poorly described and there is probably much more behind just aortic stenosis than just, for example, calcium deposits in an X-ray, et cetera, et cetera.
Dr Carolyn Lam: You used some very unique resources in Sweden to therefore look at the proteomic signatures of aortic stenosis. Could you describe that and simplify perhaps the results so we can understand it?
Dr Stefan Söderberg: First of all, I got this idea from other studies done up in northern Sweden. If you have an absolutely unique setting, the combination of huge population-based studies in 30 years back, we have a huge biobank with examples of extraordinary good quality from each of these participants. For example, for each participant, the blood has been spun and put into freezer, deep freezer, within one hour for 30 years, and they are now, as I said, about 100000.
Furthermore, I'm working as a cardiologist at a university, and up here, you do all of the aortic surgery for the whole northern Sweden. That is, we can combine the names of the person undergoing surgery together with these population-based surveys and we can get details from all those who have participated in the surveys long before they did the surgery, and they can go and retrieve samples from cases and match controls from the freezers. It's a unique setup. Then, when we were designing the study, we got the chance to get these analyses done by our friends at the university to get the proteomic analysis via a unique data technique.
Dr Carolyn Lam: Wow. Could you describe your results?
Dr Stefan Söderberg: The results that we found in the first set of 334 patients who underwent surgery is 10 years after their first sampling, we found six proteins. Then, we got the question back from Circulation to establish a validation cohort, and we were able to do so to include all those new cases in the last 2 years, and there we could replicate five of these proteins.
The interesting thing that the pattern is completely different between those having coronary artery disease from those without. That kind of phenotyping has not been done throughout other aortic stenosis studies. Therefore, this study is unique. We have had two papers in the last year in the Journal of American Heart Association from the cohort, as well, showing the thing that happened.
For example, lipoprotein little A is only associated with future aortic stenosis valve replacement only in those with concomitant coronary artery disease. There are many unique things, the prospective design, and the phenotype differentiating those with and without coronary artery disease.
Dr Carolyn Lam: Yeah, and if I may just reiterate that the population base that you work with is just enviable and just so that the audience realizes, these are biomarkers that were collected 11 years before the aortic stenosis surgery, isn't it? You really had a long follow-up.
Also, just to let everyone know, it was a proximity extension assay that you used for the discovery, and the six proteins were growth differentiating factor 15, or GDF15, galectin-4, von Willebrand factor, interleukin 17 receptor A, transferrin receptor protein 1, and PCSK9, so very interesting. Peipei, you have a way of putting things into context so beautifully. Could you tell us your thoughts when you saw this paper?
Dr Peipei Ping: I thought this is a very high-quality study that actually benefited from the long-term established, well-controlled cohort in northern Sweden, as Dr Söderberg just shared with us. On the other end, it married a technology platform that's very well-established and -validated, and this situation targeted proteomics platforms using multi-proximity extension assays with carefully controlled markers and screened 92 cardiovascular candidate markers.
This is the kind of approach that provides semi-quantitative as well as quantitative outputs and is capable to offer validated screens on large population clinical subsets. A study of such with a high value cohort combined with a validated and well-controlled technology platform offered results that clearly have clinical significance, as well as setting up examples for other studies to follow. The enthusiasm from the editorial boards, as well as the reviewers, have been substantially high and supportive.
Dr Stefan Söderberg: Fantastic. I'm very glad to hear this.
Dr Carolyn Lam: Stefan, you also mentioned that a very unique element was the separation of aortic stenosis with and within coronary artery disease, or at least established or visible coronary artery disease. Could you explain how that provided pathophysiologic insights?
Dr Stefan Söderberg: First, I should say we were very, very strict. Our routine is that everyone was 100% undergoing, aortic valve replacement, they undergo a coronary angiogram before. If we saw any sign of atheromatosis, it was not enough that they had the significant stenosis, but any signs, they were put into the group of coronary artery disease. Those without, we couldn't see anything there. Radiograph here reported absolutely clean coronary arteries. Of course, we cannot exclude if there were aortic changes within them all, of course.
We believe that this is a very important message that in order to further study aortic stenosis, we should be very careful in phenotyping the disease. We hope the growing cohort will be able to do this further. For example, cuspid versus tricuspid valves, women versus men, et cetera.
My answer in short is phenotype. Let me take one example which I found very, very exciting. That is the finding of PCSK9, which is closely related not only to cholesterol symptoms, but also to lipoprotein little A emphasis. As you know, the first strong finding in aortic stenosis was the LP little A. This is related to that genetic finding, and that was in the huge study from Canada. They did not have the same phenotyping, so we had information to his important findings. That's one example.
Another example is the transferring receptor, where data has shown that bleeding acutely in the valvular tissue causes damage, and this relates iron metabolism to the formation of the aortic valve. Obviously, it seems that the process in the aortic valve is very much similar to the vessel arteriosclerosis. It seems to be different. This is the indication that when we formulate new studies or new drugs on aortic stenosis, we must be very careful to use the right drug for the right type of valvular disease.
Dr Carolyn Lam: Those are great points. Peipei, do you think that's the main clinical take-home message, beyond that great comment you made earlier that this paper's just a great example of the use of tools, modern tools, that we have in proteomic characterization like the proximity extension assay to provide pathophysiologic insights when you have a really well-phenotyped cohort? What's the critical take-home message, though? Is there one now?
Dr Peipei Ping: The take-home message is marriage of amazing high value cohort's data sets with that of the well-controlled clinical study using target proteomics approaches. In this particular study, one main critical innovation is the study is capable of providing insights regarding molecular signatures that have predicted values. As stated in the manuscript, the circulating proteins that found critically important, their alterations took place years before the surgery were associated with aortic stenosis. That is of value, clinical value, to many other clinical studies to follow.
Dr Carolyn Lam: Wow. That's wonderful. Thank you so much for putting these findings in context for us. Thank you, listeners, for joining us today. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
Does measuring baseline BNP add prognostic information in patients undergoing revascularization for left main coronary artery disease? Well, to find out the answers, you have to stay tuned and listen up for our feature discussion coming right up, after these summaries.
The first original paper this week reports a new role for bone morphogenetic protein 9, or BMP9, as an endogenous inhibitor of cardiac fibrosis. Now, we are familiar with transforming growth factor beta-one, or TGF-β1, as a promoter of cardiac fibrosis. TGF-β1 also activates counterregulatory pathways that serve to regulate TGF-β1 activity in heart failure. BMP9 is a member of the TGFβ family of cytokines and signals via the downstream effector protein Smad1.
In the current paper from first author Dr Morine, corresponding author Dr Kapur, from Tufts Medical Center in Boston, and their colleagues. The authors examined BMP9 expression and signaling in human cardiac fibroblasts and human subjects with heart failure. They utilized the thoracic aortic constriction–induced model of heart failure to evaluate the functional effect of BMP9 signaling on cardiac remodeling. The authors’ results identified a novel functional role for BMP9 as an endogenous inhibitor of cardiac fibrosis due to LV pressure overload. They further showed that treatment with either recombinant BMP9 or inhibiting a high affinity receptor for BMP9 known as endoglin promoted BMP9 activity and limited cardiac fibrosis in heart failure. Thus, this provides a potential novel therapeutic approach for patients with heart failure.
The next paper shows that endothelial C-type natriuretic peptide, or CNP, regulates microcirculatory flow and blood pressure. First author, Dr Špiranec, corresponding author Dr Kuhn, and colleagues from University of Würzburg in Germany analyzed whether vasodilating response to CNP changed along the vascular tree. In other words, whether the guanylyl cyclase–B receptor was expressed in microvascular types of cells. The authors used novel gene-modified mouse models to show that guanylyl cyclase–B cyclic GNP signaling in parasites diminished microcirculatory resistance and arterial blood pressure. In contrast, endothelial, or macrovascular smooth muscle cell guanylyl cyclase–B signaling was not involved. This indicated that CNP participated in the local cross talk between endothelial cells and parasites, thus playing an important role in the maintenance of normal microvascular resistance and blood pressure. Thus, pharmacological augmentation of endogenous CNP signaling in parasites may provide a useful therapeutic tool to combat increased vascular resistance and hypertension.
Has the rapid and exponential growth in transcatheter aortic valve replacement, or TAVR, demand overwhelmed capacity, thus translating to inadequate access and prolonged wait times? Well, the next paper provides some answers. First author, Dr Elbaz-Greener, corresponding author Dr Wijeysundera, from University of Toronto, evaluated temporal transient TAVR wait times and the associated clinical consequences in their population-based study of all TAVR referrals from April 2010 to March 2016 in Ontario, Canada. Their study cohort included 4,461 referrals, of which 50% led to a TAVR, 39% were off-listed for other reasons, and 11% remained on the wait list at the conclusions of the study.
For patients who underwent a TAVR, the estimated median wait time in the post reimbursement period stabilized at 80 days and has remained unchanged. The cumulative probability at 80 days of wait-list mortality was 2% and of heart failure hospitalization, 12%, with an increase in events with increased wait times. Thus, post reimbursement wait time has remained unchanged for patients undergoing a TAVR procedure, suggesting that the increase in capacity has kept pace with the increase in demand. The current wait time of almost 3 months is associated with important morbidity and mortality, suggesting a need for greater capacity and access.
The final paper shows that patients with type 2 diabetes and a history of heart failure are particularly likely to benefit from treatment with the SGLT2 inhibitor canagliflozin. First author, Dr Rådholm, corresponding author Dr Figtree, from Royal North Shore Hospital in Australia, and colleagues, studied more than 10,000 participants with type 2 diabetes and high cardiovascular risk in the CANVAS Program who were randomly assigned to canagliflozin or placebo and followed for a mean of 188 weeks. Participants with a history of heart failure at baseline constituted 14.4% of the study population and were more frequently women, white, and hypertensive, with a history of prior cardiovascular disease. The benefit of canagliflozin on cardiovascular death and hospitalized heart failure was greater in patients with a prior history of heart failure compared to those without heart failure at baseline with a p for interaction of 0.02. The effects of canagliflozin compared with placebo on other cardiovascular outcomes and key safety outcomes were similar in patients with and without heart failure at baseline. Effects were apparent across a broad range of participant subgroups, including those using established treatments for the prevention of heart failure, such as renin-angiotensin-aldosterone system inhibitors, diuretics, and beta-blockers. Thus, patients with type 2 diabetes and a history of heart failure may be particularly likely to benefit from treatment with canagliflozin. The beneficial effects of canagliflozin on heart failure outcomes unlikely to be accrued on top of other therapies for heart failure management.
And that brings us to the end of this week's summaries, now for our feature discussion.
In patients with left main coronary artery disease who are undergoing revascularization, could BNP assessment be that precision medicine tool to aid us in our clinical decision making? Well, I am just so excited to discuss this very topic with the corresponding author for this feature paper, Dr Gregg Stone from Columbia University Medical Center, as well as our associate editor and editorialist for this paper, Dr Torbjørn Omland from University of Oslo.
Gregg, it was a super smart idea to look at circulating BNP and how this may associate with outcomes, as well as therapies in the EXCEL trial. Please tell us what inspired you to do this and please tell us what you found.
Dr Gregg Stone: As everybody knows, BNP has been identified as an important prognostic factor in patients with heart failure and ischemic heart disease. It correlates with both cardiovascular and noncardiovascular mortality. Patients with left main disease are among the highest-risk patients that either interventional cardiologists or cardiac surgeons treat because of the amount of myocardium at risk, they often present in heart failure, and even if they're not in overt heart failure, they can be prone to large severe left ventricular dysfunction. So first we wanted to establish the prognostic utility of BNP in this patient population and then we were interested to see if it might have a role in helping differentiate which patients might have a better prognosis with either PCI or coronary artery bypass graft surgery.
EXCEL is the largest trial to date of left main PCI versus CABG in a randomized format with 1905 enrolled patients. And overall, we found that PCI and CABG had similar rates of deaths, large myocardial infarction, or stroke in 3 years. But of course, there are high risk-patients and low-risk patients buried within those overall aggregate outcomes, and BNP was an important prognostic predictor of overall mortality in the trial. Both cardiovascular and noncardiovascular, but not of any other ischemic end points interestingly. Not myocardial infarction, stent thrombosis, graft occlusion, bleeding, revascularization. But definitely, mortality. Even independent of left ventricular ejection fraction and heart failure status.
Now, when we looked at the outcomes of PCI versus bypass surgery, we actually found a very powerful interaction, such that at relatively lower BNP levels, patients who underwent PCI had a better prognosis and tended to have lower mortality. Where patients with high baseline BNP levels tended to have a better prognosis after surgery.
Dr Carolyn Lam: You know, Torbjørn, I love your editorial where you contextualize these findings so nicely. Could you do that for us now?
Dr Torbjørn Omland: First, I would like to congratulate Gregg and his team with this very interesting and very well-done study, and I think Circulation is very fortunate to be able to publish papers like this. We have known for quite a long time that BNP is a strong prognostic indicator across the spectrum of cardiovascular diseases and it seems to be particularly strongly associated with risk of heart failure events, cardiac arrhythmias, and risk of death. And, as shown in the EXCEL trial, the association with left ventricular ejection fraction is actually quite weak, and also the association with ischemic events. So, these findings fit very well with previous observations. The really novel and intriguing finding of this study is the very strong interaction between procedural BNP levels and the effect of the randomized therapies and, as you alluded to, all the investigators have tried to look at this in other more low-risk populations like in the LIPID trial but actually failed to find any significant interaction. It's really a novel and important finding.
Dr Carolyn Lam: That's true. Does it bring up the question are the natriuretic peptides just a better EF measurement? You mentioned that there was a correlation, what do you think, Gregg?
Dr Torbjørn Stone: Well, you know, there was a weak correlation between BNP and ejection fraction and history of heart failure but the prognostic utility of BNP in this study and its ability to differentiate between the outcomes of PCI versus CABG in patients with low versus high BNP was actually strongly independent of both congestive heart failure history and acute left ventricular ejection fraction. So, I think the BNP is giving a useful independent information. It's a strong reflector of both atrial and ventricular pressures and volume status, but it also reflects myocardial hypoxia, it may be involved in glycolysis and lipid peroxidation, and other mechanisms that we don't fully understand. There may be elements of diastolic dysfunction that we have not measured in this study and other mechanisms related to prognosis in these patients. So, while EXCEL was not set up to truly differentiate and delve deeply into the mechanisms of our observations, statistically these were strong associations that may prove clinically useful.
Dr Carolyn Lam: Right, I thought that was so intriguing as well, just the points that you brought up. First, let's just clarify for the audience that when you say low and high you were using a cutoff of 100.
Dr Gregg Stone: We did use a cutoff of 100 pg per mL as is common, but we also modeled BNP as a continuous measure. And actually the relationships were even stronger when modeled as a log hazard ratio continuous measure, both for mortality and for the primary end point.
Dr Carolyn Lam: Yeah, that's so cool. And Torbjørn, you talked about this in your editorial as well and I thought your point about the distributions of the ejection fraction versus the distribution of natriuretic peptide, that was very revealing, too. Would you like to explain your thoughts there?
Dr Torbjørn Omland: I found it very interesting that all of this is clearly a high-risk operation overall. More than 90% actually had what we regard a normal, or at least not a reduced ejection fraction. Whereas the distribution of BNP values were more widely distributed so that actually about 40% of participants had BNP levels above this ratio of 100 pg per mL. And that probably shows that in this population, BNP provides additional and independent information about the status of the myocardium that is not revealed by angiography or ejection fraction measurements.
Dr Carolyn Lam: That's true, and that's an important point because it added above the SYNTAX score, too, right Gregg?
Dr Gregg Stone: That's right, it was an independent predictor, and in fact the SYNTAX score and the severity of left main coronary disease did not vary, according to BNP levels, that is. High versus low BNP were equally distributed, not related to the anatomic extent and complexity of coronary artery disease. So, BNP is clearly reflecting a different state of the myocardium in a way that we can't measure with any other available test and that makes it quite a useful biomarker.
Dr Carolyn Lam: Exactly, so I think I'd like to wrap up with asking you both, you can already see what the potential clinical implications are, right? Which means that perhaps in a similar type of patient where there's equipoise of the revascularization method and has left main disease, maybe we should be using natriuretic peptides to guide our clinical decision making. What do you think are next steps before this is prime time?
Dr Gregg Stone: Well I can mention that when one makes a decision of the best revascularization modality for patients with extensive multi-vessel or left main coronary artery disease, there are many factors that go into that determination, both clinical, anatomic, is the patient a good candidate for one versus the other revascularization modality, what are the patient's preferences, what's the surgeon's or interventionalist's likelihood of being able to safely get the patient through the procedure and achieve complete revascularization.
The SYNTAX score makes a difference, as does gender and age and kidney disease and COPD and ejection fraction and many other factors. So I think we can now add to that list BNP, although I will say this was a post-hoc study, we only had BNP available in approximately 60% of the patients, and while the outcomes were similar in the patients who we did not versus who we did have BNP, this has to be looked at as hypothesis-generating analysis, and we would love to also see this type of finding replicated in other large datasets. That being said, there are no other large left main or new multi-vessel disease trials that are planned right now to my knowledge, and I think given the breadth of this dataset and its size and scope, I do think that these findings are robust enough to use BNP as one of the clinical factors to consider in revascularization decisions.
Dr Torbjørn Omland: I actually agree with that and I think ideally, we would, of course, like to see external validation in another dataset and even retrospective randomized study comparing conventional versus BNP-guided strategy but that may not be realistically undertaken. So, I think these are clearly the best data we have and as clinicians need to integrate this in our overall evaluation in making this important decision.
Dr Carolyn Lam: Yeah, I mean Gregg, could I ask you, do you apply this clinically already?
Dr Gregg Stone: We have not been before this, although I believe we will now. I believe BNP should be a biomarker that we more routinely measure in patients with ischemic heart disease as well as those with overt congestive heart failure. And again, use as one of the factors of many when making revascularization decisions. And I think it's important to note also that the PCI patients tended to preferentially benefit, in fact with even lower mortality when BNP was lower. Where the surgical patients tended to benefit when BNP was higher. So, it's one factor, not the only factor, but I think it's one additional piece of the puzzle.
Dr Carolyn Lam: Yeah, I have to say too I mean, after reading this, after reading this awesome editorial, it's hard not to think I should be applying this clinically because it's going to be really hard and take a long time to prove this with more prospective data, for example. Although, external validation and other datasets may be better, this is the largest trial already to show this and show it so clearly with a significant interaction. I think that is striking to me.
Torbjørn maybe I've put you on the spot with the last word, does this change your clinical practice?
Dr Torbjørn Omland: I agree with Gregg. This will be one of maybe several other factors but I think it's ready for being taken into account when making this sometimes very difficult decision.
Dr Carolyn Lam: Thank you so much Gregg and Torbjørn for joining me today. You've been listening to Circulation on the Run. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. Did you know that despite being one of the wealthiest nations in the world, the United States population has a shorter life expectancy compared to almost all other high-income countries in the world? Well, stay tuned to learn what Americans could do to narrow the life expectancy gap between the United States and other industrialized nations. Coming right up after these summaries.
Are microRNAs involved in nitrate tolerance? Well, the first original paper this week provides some answers. This is from co-corresponding authors Dr Bai and Zhang from Central South University in Changsha, China. Nitrate tolerance develops when there's dysfunction of the prostaglandin I2 synthase and prostaglandin I2 deficiency. These authors hypothesize that prostaglandin I2 synthase gene expression may be regulated by a microRNA-dependent mechanism in endothelial cells. They induce nitrovasodilator resistance by nitroglycerin infusion in Apoe deficient mice and studied endothelial function in both the mouse models as well as human umbilical vein endothelial cells. They found that nitric oxide donors induced atopic expression of microRNA 199a/b in endothelial cells, which was required for the nitrovasodilator resistance via repression of prostaglandin I2 synthase gene expression. Targeting this axis effectively improved nitrate tolerance. Thus, the atopic expression of microRNA 199 in endothelial cells induced by nitric oxide may explain prostaglandin I2 synthase deficiency in the progression of nitric tolerance. Thus, microRNA 199a/b may be a novel target for the treatment of nitric tolerance.
What are the long-term outcomes of childhood left ventricular noncompaction cardiomyopathy? Well, the next paper presents results from the National Population-Based Study in Australia. First author, Dr Shi, corresponding author, Dr Weintraub, from Royal Children's Hospital in Melbourne, looked at the National Australian Childhood Cardiomyopathy Study, which includes all children in Australia with primary cardiomyopathy diagnosed at less than 10 years of age between 1987 and 1996. Outcomes for left ventricular noncompaction patients with a dilated phenotype will compare to those with a dilated cardiomyopathy.
There were 29 patients with left ventricular noncompaction with a mean annual incidence of newly diagnosed cases of 0.11 per hundredth thousand at risks persons.
Congestive heart failure was initial symptom in 83%, and 93% had a dilated phenotype. The median age at diagnosis was 0.3 years of age. Freedom from death or transplantation was 48% at 10 years after diagnosis, and 45% at 15 years. Using propensity score inverse probability of treatment-weighted Cox regression, the authors found evidence that left ventricular noncompaction with a dilated phenotype was associated with a more than two-fold greater risk of death or transplantation.
The next paper reports the first application of multiomics and network medicine to calcific aortic valve disease. Co-first authors Dr Schlotter and Halu, corresponding author Dr Aikawa from Brigham and Woman's Hospital and Harvard Medical School in Boston, and their colleagues examined 25 human stenotic aortic valves obtained from valve replacement surgeries. They used multiple modalities, including transcriptomics and global unlabeled and label-based tandem-mass-tagged proteomics.
Segmentation of valves into disease stage–specific samples was guided by near-infrared molecular imaging. Anatomic-layer specificity was facilitated by laser capture microdissection. Side-specific cell cultures was subjected to multiple calcifying stimuli, and the calcification potential and basil or stimulated proteomics were evaluated. Furthermore, molecular interaction networks were built, and their central proteins and disease associations were identified.
The authors found that global transcriptional and protein expression signatures differed between the nondiseased, fibrotic, and calcific stages of calcific aortic valve disease. Anatomical aortic valve microlayers exhibited unique proteome profiles that were maintained throughout disease progression and identified glial fibrillary acidic protein as a specific marker of valvula interstitial cells from the spongiosa layer. In vitro, fibrosa-derived valvular interstitial cells demonstrated greater calcification potential than those from the ventricularis. Analysis of protein-protein interaction networks further found a significant closeness to multiple inflammatory and fibrotic diseases. This study is significant because it is the first application of spatially and temporarily resolved multiomics and network systems biology strategy to identify molecular regulatory networks in calcific aortic valve disease. It provides network medicine–based rational for putative utility of antifibrotic and anti-inflammatory therapies in the treatment of calcific aortic valve disease. It also sets a roadmap for the multiomic study of complex cardiovascular diseases.
The final paper tackles the controversy of antibiotic prophylaxis for the prevention of infective endocarditis during invasive dental procedures. This is from a population-based study in Taiwan. First author, Dr Chen, corresponding author, Dr Tu from Institute of Epidemiology and Preventive Medicine College of Public Health in National Taiwan University aimed to estimate the association between invasive dental treatments and infective endocarditis using the health insurance database in Taiwan.
They chose 2 case-only study designs. First a case-crossover, and second, self-controlled case series. Both designs used within-subject comparisons such that confounding factors were implicitly adjusted for. They found that invasive dental treatments did not appear to be associated with a larger risk of infective endocarditis in the short period following invasive dental treatment. Results were consistent from both study designs. The authors also did not find any association between invasive dental treatments and infective endocarditis even among the high-risk patients, such as those with a history of rheumatic disease or valve replacement.
In summary, these authors found no evidence to support antibiotic prophylaxis for the prevention of infective endocarditis before invasive dental treatments in the Taiwanese population. Whether antibiotic prophylaxis is necessary in other populations requires further study.
Alright, so that wraps it up for our summaries, now for our feature discussion.
The United States is one of the wealthiest nations worldwide, but Americans have a shorter life expectancy compared with almost all other high-income countries. In fact, the US ranks only 31st in the world for life expectancy at birth in 2015. What are the factors that contribute to premature mortality and life expectancy in the US? Well, today's feature paper gives us some answers. And I'm just delighted to have with us the corresponding author, Dr Frank Hu from Harvard T.H. Chan School of Public Health, as well as our dear associate editor, Dr Jarett Berry, from UT Southwestern.
Frank, could you begin by telling us a bit more about the inspiration for looking at this, what you did, and what you found?
Dr Frank Hu: So, we look at the impact of healthy lifestyle habits, life expectancy in the US as a nation. As you just mentioned, Americans have a shorter life expectancy compared with almost all other high-income countries, so in this study we wanted to estimate what kind of impact of lifestyle factors have, premeasured that and life expectancy in the US population.
What we did is to combine three datasets. One is our large cohort, Nurses’ Health Study, and Health Professionals Follow-Up Study. We use this large cohort to estimate the relationships between lifestyle habits and mortality. And the second data set we use is to get age and sex to specific mortality rates in the US as a nation. This is the CDC WONDER dataset. And the third dataset we used is the NHANES dataset, this is the National Health and Nutrition Examination Survey. We used this dataset to get the prevalence of healthy lifestyle factors in the general US as a nation. So, we used the three datasets to create age-specific, sex-specific life tables and estimated life expectancies.
At age 50, according to the number of healthy lifestyle habits that people would follow, what we found is that following several lifestyle factors can make a huge difference in life expectancies.
Here we talk about five basic lifestyle factors: not smoking, maintaining a healthy weight, exercise regularly—at least a half hour per day—and eating a healthy diet, and not drinking too much alcohol. No more than one drink per day for a woman, no more than two drinks per day for men. What we found is that, compared with people who did not adapt any of those low-risk habits, we estimated that the life expectancy at age 50 was 29 years for woman and about 26 years for men. But for people who adapted all five healthy lifestyle habits, life expectancy at age 50 was 43 years for women and 38 years for men. So, in other words, a woman who maintains all 5 healthy habits gained, on average, 14 years of life, and the men who did so gained 12 years life compared with those who didn't maintain healthy lifestyle habits. So I think this is a very important public health message. It means that following several bases of healthy factors can add substantial amount of life expectancy to the US population, and this could help to reduce the gap in life expectancy between the US population and other developed countries.
Dr Carolyn Lam: Thank you, Frank. You know that is such an important public health message that I am going to repeat it. Adhering to five lifestyle risk factors mainly, don't smoke, maintain a healthy weight, have regular physical activity, maintain a healthy diet, and have moderate alcohol consumption, AND a woman could increase her life expectancy at age 50 by 14 years and a man could do that by 12 years more. That is absolutely amazing.
Okay so Frank, actually, I do have a question though. These are remarkable datasets obviously, but they also go back to the 1980s. So did you see any chief risk factor that may have played more predominant apart with time?
Dr Frank Hu: We didn't specifically look at the changes in risk factors life expectancy, but among the five risk factors, not smoking is certainly the most important factor in terms of improving life expectancy. The good news is that prevalent smoking in the US has decreased substantially in the past several decades. However, the prevalence of other risk factors has actually increased. For example, the prevalence of obesity has increased two- or three-fold and the prevalence of regular exercise remained at a very low level, and also the diet quality in the US population is relatively poor. So, the combination of those risk factors have contributed to relatively low life expectancies in the US population.
Dr Carolyn Lam: Right. Obesity, not smoking, I hear you. I just wanted to point out to all the listeners too, you have to take a look at Figure 1 of this beautiful paper, it’s just so beautifully illustrated in it.
Jarett, you helped to manage and bring this paper through. What are your thoughts?
Dr Jarett Berry: Yeah, I just want to echo your comments, Carolyn, and Dr Hu. This is a fabulous paper, and a very important contribution characterizing these important associations in the US population. And I think, and the discussion thus far has been really helpful in putting all of this into context.
I do want to ask you, just a couple of, I guess more, philosophical questions about some of the observations in the paper. And one of them is the prevalence of the low-risk factor, those with a large number of low-risk factors, for example, in both the Nurses Health and in the Health Professional Follow-Up Study, you observed that the presence of five lifestyle factors was less than 2%. And it's interesting you see this in a large number of datasets and I think important, maybe for our readers to realize that there's two sides to the coin here.
One, the benefit of these low risk factors, but also, unfortunately, the low prevalence of these collections of healthy lifestyle factors that you've outlined.
Could you comment a little bit on that, and what that means, both maybe from a scientific point of view of perhaps, more importantly, from a public health stand point?
Dr Frank Hu: Yeah and this is very important observation and the number of people or the percentage of people who maintained all the five low-risk lifestyle habits is quite low in our cohort, even the nurses and health professionals, they are more health conscience in the general population. They have much better access to health care and also better access to healthy foods and have physical activity facilities. Despite all this potential advantages, and these more percentage of people who are able to maintain all five lifestyle risk factors.
On the other hand, about 10 to 15% of our participants did not adopt any of the five low-risk lifestyle habits. So it means that we still have a lot of work to do in terms of improving the lifestyle habits that we discussed earlier. The five risk lifestyle factors and in the general population, I think the percentage of people who adapt all the five lifestyle factors, probably even lower than 2%. And so that means that we have a huge public health challenge in front of us and have to improving the five lifestyle risk factors. One of the most important public health challenges as mentioned earlier is obesity because currently we have two-third of the US population is overweight or obese. So that's something I think is major public health challenges for us.
Dr Jarett Berry: Right, and it’s interesting looking at your Table 1, and those individuals who have all five low risk factors. It's interesting that the prevalence of physical activity was incredibly high. I have a great interest of impact of exercise on these types of outcomes and it's interesting that in both cohorts, six or seven hours a week of exercise was the mean physical activity level in those with five risk factors. So, it's interesting and in some ways, these lifestyle factors, they do tend to congregate or covary with one another such that those individuals who do spend that kind of time, albeit unfortunately more rare than we would like to see it, the increase in physical activity does tend to have a positive impact, not only on the weight, but also on healthy lifestyle or healthy diet choices.
Dr Frank Hu: Right, yeah this is a very good observation that what I do want to point out that our definition of regular exercise is pretty cerebral to put it in terms of the definition. So we define moderate to vigorous physical activity in our cohorts. We included not just running, playing sports, but it was also walking in a moderate intensity. So it means that people can incorporate physical activity into their daily life. For example, by walking from a train station and with climbing stairs in their workplace and so on and so forth. So here physical activity means both recreational activity and also moderate intensity activities such as graceful walking.
Dr Carolyn Lam: Frank, I think both of us listening are breathing a sigh of relief there and just for the listeners to understand too. These factors were dichotomized, right, and so you were describing the type of exercise and actually you used a three and a half hour per week limit to define healthy or not.
Similarly, just for reference the alcohol intake was 5 to 15g a day for women, or 5 to 30g a day for men. And normal weight was defined as a BMI of 18.5 to 24.9. I'm just thinking that if I were listening I'd want to know those cutoffs.
Now, can I ask a follow-up question, therefore to this dichotomy. As far as I understand you counted each of these risk factors equally, but did you try to do a weighted analysis by any chance? Did any one of them play a bigger role than others?
Dr Frank Hu: That's an interesting mathematical question because it’s very difficult to assign different weights to different risk factors because we look at, not just total mortality but also cardiovascular mortality and cancer mortality. So, you would have to use different weights for different causes of mortality. That would make the analysis much more complicated. But we did calculate a different type of score using five categories of each risk factor and then using that score, we were able to rank people in more categories so for that score the range is from five to 25, and we categorized people into quintiles or even more categories and the contrast in life expectancy between the lowest and the highest group is even greater. So, it means that, the higher number of healthy lifestyle factors, the greater life expectancy. Also, with each category, each lifestyle factors a high degree of adherence to that factor, the greater health benefit people will get. So, I think it's really accumulative fact of multiple risk factors and also the degree of adherence to each of the factors.
Dr Carolyn Lam: Again, such an important public health message.
Jarett, how do you think this is going to be received by the public at large?
Dr Jarett Berry: Very well received. I mean this is a very important observation demonstrating some of these disconcerting observations about life expectancy in the United States and as we think about strategies for improving the public health, I think Dr Hu's group has really helped us outline, very clearly, what other bodies such as the American Heart Association have been saying for years now, that lifestyle factors are so important in influencing cardiovascular risk, and in this case, life expectancy. It really does put, once again, the right amount of emphasis on the role these lifestyle factors of improving the public health. I think it’s going to be very well received and really helpful and important observation that all of us need to hear.
Dr Carolyn Lam: Listeners, don't forget this important message and tell your friends about it, please.
Thanks for joining us today, don't forget to join us again next week.
Dr Carolyn Lam: Welcome to Circulation On the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
In this day and age of endovascular treatment for acute ischemic stroke, does time to treatment really matter? Well, we will be discussing results of the MR CLEAN Registry from real-world clinical practice, coming right up after these summaries.
The first original paper this week describes the first mouse model of progerin-induced atherosclerosis acceleration. Progerin is an aberrant protein that accumulates with age, causes a rare genetic disease known as Hutchinson-Gilford Progeria Syndrome. Patients with Progeria Syndrome have ubiquitous progerin expression and exhibit accelerated aging and atherosclerosis, dying in their early teens mainly from myocardial infarction or stroke. The mechanisms underlying progerin-induced atherosclerosis remain unexplored, in part due to the lack of appropriate animal models. First author Dr Hamczyk, corresponding author Dr Andrews, and colleagues from CNIC in Madrid performed an elegant series of experiments and generated not only the first mouse model of progerin-induced acceleration of atherosclerosis, but also provided the first direct evidence that progerin expression restricted to vascular smooth muscle cells but not to macrophages was sufficient to induce premature atherosclerosis and death. Progerin-induced loss of vascular smooth muscle cells caused atherosclerotic plaque destabilization that led to myocardial infarction. Ubiquitous and vascular smooth muscle cell specific progerin expression increased LDL retention in aortic media, likely accelerating atherosclerosis.
The next original paper implicates dysregulation of mitochondrial dynamics as a therapeutic target in human and experimental pulmonary arterial hypertension. Now, mitotic fission is increased in pulmonary arterial hypertension. The fission mediator, dynamin-related protein 1, or Drp1, must complex with adaptor proteins to cause fission. In the current paper from co-first authors Dr Chen and Dasgupta, corresponding author Dr Archer from Queens University in Ontario Canada, and colleagues, the authors examined the role of two recently discovered but poorly understood Drp1 adaptor proteins known as mitochondrial dynamics protein of 49 and 51 kilodalton. They found pathological elevation of these mitochondrial dynamic proteins in pulmonary artery smooth muscle cells and endothelial cells in both human and experimental pulmonary arterial hypertension that accelerated mitotic fission and supported rapid cell proliferation. Mitochondrial dynamics protein's expression was epigenetically upregulated by a decreased expression of microRNA-34a-3p. Circulatory microRNA-34a-3p expression was decreased in both patients with pulmonary arterial hypertension and preclinical models, silencing the mitochondrial dynamics proteins or augmenting microRNA-34a-3p regressed experimental pulmonary arterial hypertension, thus, proving to be potential new therapeutic targets for pulmonary arterial hypertension.
Dyslipidemia guidelines currently recommend that non-HDL cholesterol and apolipoprotein B, or apoB, are secondary targets to the primary target of LDL cholesterol. However, how frequently does non-HDL cholesterol guideline targets change management, and what is the utility of apoB targets after meeting LDL and non-HDL targets?
Well, answers are provided in the next paper from first author Dr Sathiyakumar, corresponding author Dr Martin, and colleagues from Johns Hopkins University School of Medicine. These authors analyzed more than 2,500 adults in the US National Health and Nutrition Examination Survey, as well as more than 126,000 patients from the Very Large Database of Lipids Study with apoB. They identified all individuals as well as those with high-risk clinical features, including coronary disease, diabetes, and metabolic syndrome who met the very high and high-risk guidelines targets of LDL cholesterol of less than 70 and less than 100 mg/dL, respectively, and this was measured using either the Friedewald estimation or a novel, more accurate method. They found that after using the more accurate method of estimating LDL cholesterol, guidelines suggested non-HDL targets could alter management in only 1 to 2% of individuals, including those with coronary disease and other high risk clinical features.
However, using the Friedewald estimated LDL cholesterol gave a much higher percentage. Among all individuals with both LDL cholesterol less than 100 and non-HDL cholesterol less than 130 mg/dL, only 0-0.4% had an apoB above or equal to 100 mg/dL. Thus, the utility of current non-HDL targets appears to be contingent on the accuracy of LDL cholesterol estimation. When using a novel, more accurate estimation method to assess LDL cholesterol, the non-HDL cholesterol is infrequently above current guidelines' suggested targets after the LDL target is met. Current guidelines suggest that apoB targets also provide only modest utility after cholesterol targets are met. These findings were robust to high-risk clinical features, sex, fasting status, and presence of lipid-lowering therapies.
The final paper tells us that HIV infection increases the risk of developing peripheral artery disease. Dr Beckman from Vanderbilt University Medical Center and colleagues studied almost 92,000 participants in the Veterans Aging Cohort Study from 2003-2014 over a median follow-up of nine years. They excluded participants with known prior peripheral artery disease or prevalent cardiovascular disease. They found that infection with HIV was associated with a 19% increased risk of incident peripheral artery disease beyond that explained by traditional atherosclerotic risk factors. Once peripheral artery disease had developed, HIV infection increased the risk of mortality compared to uninfected patients. Whereas for those with sustained CD4 cell counts above 500, there was no excess risk of incident peripheral artery disease events compared to uninfected people. Furthermore, worsening HIV infection as measured by CD4 cell count and HIV viral load was associated with increased incident peripheral artery disease and mortality. In summary, HIV infection increased the risk of developing peripheral artery disease and mortality. The findings also suggest that aggressive antiretroviral therapy to reduce viral load and increase CD4 cell counts may reduce the risk of developing peripheral artery disease. Furthermore, clinicians should solicit clinical complaints and physical signs consistent with peripheral artery disease to facilitate the diagnosis of peripheral artery disease in patients with HIV and ensure the addition of guideline-based anti-atherosclerotic therapies in these patients.
Well, that wraps it up for our summaries. Now for our feature discussion.
When it comes to acute ischemic stroke treatment, we've learned from trials of intravenous thrombolytics that time is brain. But what about the situation with endovascular treatment of strokes? Also, what's the situation like in the real world? Well, today's featured paper really provides precious data telling us about time-to-endovascular treatment and outcomes in acute ischemic stroke. I am so delighted to have with us the first and corresponding author of the MR CLEAN Registry, Dr Maxim Mulder from Erasmus University Medical Center, as well as our editorialist, Dr Micheal Hill, from University of Calgary, and our associate editor, Dr Graeme Hankey, from University of Western Australia, all here to discuss this hugely important topic.
Maxim, could we start with you? So, MR CLEAN Registry means there was a MR CLEAN trial. Could you tell us a little bit more about your paper?
Dr Maxim Mulder: Sure, well to start with, I think it's important to make sure all the people know the difference between the MR CLEAN trial and the registry since of course the trial was to show whether the intra-arterial treatment is effective when it comes to acute ischemic stroke treatments and then, of course, for people treated within six hours. When the MR CLEAN trial finished we continued in the Netherlands with all the participating centers from the trial to gather all the data from everybody who is treating in the whole country with the intra-arterial treatment, but they're not anymore in the light of the trial but in the clinical practice. We've had a lot of trials, but we don't have a lot of clinical practice date yet of the intra-arterial treatment, so that's where it all started.
So, what we found is we consider our data, so with the least possible selections or the only selection was basically to treat within six and a half hours and have patients that had a proven large vessel occlusion that were treated in the Netherlands and of course as we also know from when intravenous therapy was introduced that what happens in clinical trials doesn't necessarily happen when a new treatment is introduced into clinical practice. There are less strict criteria for patients to get treated, and you know everybody, of course, there is a lot of debate about which patients should be treated. In clinical trials it is very strictly coordinated, but in clinical practice there's a lot more room to have an interpretation and also treat a different population. So, we also see that our population is somewhat older and has more comorbidities than in all the trials. Also what we found, of course, our most important finding was that when compared to all the trials or the large trials combined together in the Emberson analysis about time that when we look at the influence or the association of time with functional outcome of intra-arterial treatment that this association is clearly stronger than we found in the previous, the trial data.
So, I think that's a very important finding. Also, for everybody who's now treating this patient in clinical practice.
Dr Carolyn Lam: Exactly. I mean this is really stunning results. If I could paraphrase from your paper, every hour delay in time from stroke onset to the start of endovascular treatment resulted in a 5.3% decreased probability of functional independence and a 2.2% increase in mortality. This is stunning. Thank you, thank you for publishing these results with us in Circulation. I would like to ask Michael, I love the point you made in the editorial that time of stroke onset is really quite a difficult thing to determine. Could you tell us your thoughts about that, Michael?
Dr Micheal Hill: I mean, it's something like 15-20% of the time stroke is unwitnessed, either because stroke occurs in sleep and the patient is discovered with their stroke symptoms on awakening. Or the patient is simply alone and has their stroke unwitnessed by any bystander. Even in so-called witness stroke, there are probably significant errors in determining the exact time of stroke onset because it's an emergency, and everybody's flustered and time anchors are not necessarily well known. And, so, I think it's an important point that the actual measurement of time is challenging, yet it's still an easier clinical tool for us to use in gauging the extent or evolution of stroke. That's the most important thing to point out here is that this population effect that Max has observed in the MR CLEAN registry is certainly concordant with clinical trial data.
I certainly think it's correct, and, as you pointed out in your comments, dramatic, but a really important issue is that for the individual patient, there's quite a lot of variance in the evolution of stroke. So, whereas, on a population basis, it's absolutely true that the average time from estimated time of stroke onset to treatment initiation is absolutely critical; in some patients, the individual might be still a good candidate for treatment even in late time windows, and some patients, even after a couple hours, the damage is already extensive, and they may not be good candidates for treatment. It still requires individual decision making, and it still leaves a lot of room for clinical judgment largely based on imaging.
Dr Carolyn Lam: True, and I think you've really succinctly put that solid take-home message in the title really, which is acute ischemic stroke biology really demands fast treatment. I think that's the one thing that we'd really like clinicians to come away with. You agree?
Dr Micheal Hill: Absolutely. Especially, I think, the advantage of looking at whole populations and large, I mean this is a large registry, the MR CLEAN registry, and the group should be congratulated because it's clearly the biggest registry in the world right now of available data, and it's only getting larger week by week as they carry on with their work. You know the whole Netherlands group, the MR CLEAN group, are a fantastic group, but absolutely right, on a population basis, we absolutely have to get our systems in place so that on average we're treating patients incredibly fast. On an individual basis, the clinicians and the teams treating an individual patient still need to make judgments about that patient's eligibility for treatment. It's easy when the times are fast, so if you're an hour and a half from onset, nearly everybody's gonna be a good candidate for treatment, but as time elapses you need to make judgements on the basis of imaging.
Dr Carolyn Lam: Well put. You know, Graeme, you're over there in Australia. What are your take-home messages about how generalizable these findings are to places outside perhaps of the Netherlands?
Dr Graeme Hankey: I think you're asking about the external validity. I think the internal validity is certainly there. As Michael said, this is the largest registry that we have that's been published data on this before. It's certainly novel, and we're very confident that the results are valid, although this is an observational study and not a randomized trial. The association between time and outcome seems to be independent of the major patient factors that may influence time to endovascular therapy. For example, younger people who are less frail and they're alert and they're mobile can get to treatment earlier. So, you might say, well of course they're gonna have a better outcome. But these factors were adjusted for. And, of course, there are procedural factors that could influence the association between time and outcome, but we're very confident in the results and the novelty of them in supporting and building on the randomized trial data.
We're also very confident in the registry and the nature of the population. The results are likely to be generalizable beyond the Netherlands population where this was conducted in routine clinical practice, certainly across Caucasian populations that are similar and with similar stroke interventional and assessment protocols, and I would hope to see this sort of study validated externally in other populations. But, also, as Michael said, I think this study not just highlights the importance of time as a factor and its implications for systems of care and recognizing people with disabling stroke and ensuring they’re assisted urgently to the appropriate imaging but also to acknowledge that time isn't the only factor. And as Michael has alluded to, our brain tissue has different collateral circulations and different probable genetic factors and metabolic factors. So, someone with a stroke at one hour, it might be all over for them. Whereas, another person with a stroke at 24 hours ago, they might have salvageable tissue.
So, although, generally time is an important prognosticator as we've learned here, there are probably other factors that need to be considered and accounted for. But this certainly takes us a step forward, and, in answer to your question, I think we have confidence in its generalizability.
Dr Carolyn Lam: Thank you Graeme. Maxim, in line with that, are there any next steps you plan?
Dr Maxim Mulder: In light of the most recent trials, the DAWN and DEFUSE 3 trial about 6 to 25-hour, 24-hour window, I think that both of the trials are very exciting, and they shine a new light into a new set of patients that are still able to offer a great benefit intra-arterial treatment. In my opinion, the most important thing, especially in those two trials, those are highly selective patients, especially selected on all the extra imaging parameters, and I guess that there's a whole larger population that could still benefit in this time window and that's also one of the things we're currently studying in one of our new trials in the Netherlands in the MR CLEAN-LATE trial, and that is randomizing patients who are having a large vascular occlusion 6 to 24 hours, and the only extra criteria they should meet is they should have at least a little bit of collateral circulation on the ischemic brain side.
Dr Carolyn Lam: Michael and Graeme, what do you think are the priorities for next steps in research.
Dr Micheal Hill: I guess overall in the field, I don't think there's any doubt that faster treatment is better. What we need to do across the world is make sure that everybody's receiving it on a system-wide basis. Right? I think there needs to be a lot of more careful work done on getting systems of care in place to make sure that patients are getting the treatment they can get. We have very many weaknesses. Some are related to lack of accreditation. Some are related to the resources required to get people treated quickly. Some are related to continuing resistance in some specialties to even giving intravenous thrombolytic drugs. So, I think faster treatment in general for acute stroke is a theme; it's not just limited to endovascular treatment. It's treatment for patients for intravenous thrombolysis. It's also actually true for TIA and minor stroke. We've had recent data on fast antiplatelet therapy, so, it's not an emergency in the same way in terms of minutes, but it's still a general theme of acute stroke care.
We need to be like the Ferraris and the Formula One, right? And get ourselves moving. That's a big challenge for people. Right? It's a big stress on systems. But, I think there are other examples in medicine. We've seen this evolution in acute coronary care, and we've seen the evolution in acute trauma care. In many ways, the next things that need to really continue to happen are publications like this and getting the message out that people need to start changing their mind. The biggest thing that I find when I talk to people or talk at meetings or talk to administrators is that they say, "Well, we can't do this many CTs that fast. We can't respond that fast." And the answer is actually that you can't change the biology of the disease, so if you decide you wanna treat stroke patients, you better figure out how to change your systems. It's a question of will here rather than trying to bend the disease to the system.
Dr Carolyn Lam: Wonderfully put. Can't change the biology so we better change the systems. How about you, Graeme? Any last words?
Dr Graeme Hankey: Just to concur with Michael’s comments there and Max's underlying theme that time is very important. And as Michael alludes to, it's not just acute ischemic stroke due to large vascular disease, it's also acute intracerebral hemorrhage. We're learning now really if we're gonna have an effect in the bleeding brain probably we have to do that within the first three hours and maybe not be waiting so late. And as Michael alludes to, someone with a minor ischemic stroke who's had a hot volcano gone off in their neck, as you know, ruptured atherosclerotic plaque, it's like those volcanoes in Hawaii, they're gonna keep going off again. And the risk is 5% in the next two days and 10% in the next week. So, a TIA and a mild ischemic stroke, it is a medical emergency to find the cause and to get it treated, and that's why the synopsis of this message from Max's study is that people, if they do avail themselves of acute assessment early, even if they don't have a large vessel occlusion causing an ischemic stroke, they may actually have their intracerebral hemorrhage treated quickly or, more evidence based at the moment, their TIA or mild ischemic stroke have the cause ascertained and treated emergently and reduce that early risk of recurrence should they survive.
Dr Carolyn Lam: Excellent points. Thank you so much, gentlemen. This has been an amazing podcast.
Thank you so much for joining us today. Don't forget to tune in again next week, listeners.
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 for the National Heart Center, and Duke National University of Singapore.
How do resuscitation teams at top-performing hospitals for in-hospital cardiac arrest actually succeed? Well, to learn how, you have to keep listening to the podcast, because we will be discussing this right after these summaries.
The first original paper this week tells us that recent developments in RNA amplification strategies may provide a unique opportunity to use small amounts of input RNA for genome wide-sequencing of single cells. Co-first authors, Dr Gladka and Molenaar, corresponding author, Dr van Rooij, and colleagues from Hubrecht Institute in Utrecht, the Netherlands, present a method to obtain high-quality RNA from digested cardiac tissue, from adult mice, for automated single-cell sequencing of both healthy and diseased hearts.
Based on differential gene expression, the authors were also able to identify multiple subpopulations within a certain cell type. Furthermore, applying single-cell sequencing on both the healthy and injured heart indicated the presence of disease-specific cells subpopulations.
For example, they identified cytoskeleton-associated protein 4 as a novel marker for activated fibroblasts that positively correlated with known myofibroblast markers, in both mouse and human cardiac tissue. This paper raises the exciting possibility for new biology discovery using single-cell sequencing that can ultimately lead to the development of novel therapeutic strategies.
Myeloid-derived suppressor cells are a heterogeneous population of cells that expand in cancer, inflammation, and infection, and negatively regulate inflammation. However, their role in heart failure was unclear, at least until today's paper in this week's journal. Co-first authors Dr Zhou, Miao, and Yin, and co-corresponding authors, Dr Wang and Li, from Huazhong University of Science and Technology, measured the myeloid-derived suppressor cells by flow cytometry in heart failure patients and in mice with pressure overload–induced heart failure, using isoproterenol infusion or transverse aortic constriction.
They found that the proportion of myeloid-derived suppressor cells was linked to heart failure severity. Cardiac hypertrophy, dysfunction, and inflammation were exacerbated by depletion of myeloid-derived suppressor cells but alleviated by cell transfer. Monocytic myeloid-derived suppressor cells exerted an antihypertrophic effect on cardiomyocyte nitric oxide, but monocytic and granulocytic myeloid-derived suppressor cells displayed antihypertrophic and anti-inflammatory properties through interleukin 10.
Rapamycin increased accumulation of myeloid-derived suppressor cells by suppressing their differentiation, which in part mediated its cardioprotective mechanisms. Thus, these findings revealed a cardioprotective role from myeloid-derived suppressor cells in heart failure by their antihypertrophic effects on cardiomyocytes and anti-inflammatory effects through interleukin 10 and nitric oxide. Pharmacological targeting of myeloid-derived suppressor cells by rapamycin constitutes a promising therapeutic strategy for heart failure.
In the FOURIER trial, the PCSK9 inhibitor evolocumab reduced LDL cholesterol and cardiovascular risk in patients with stable atherosclerotic disease. However, was the efficacy of evolocumab modified by baseline inflammatory risk?
While Dr Bohula from the TIMI Study Group and colleagues explored this question by examining the efficacy of evolocumab stratified by baseline high sensitivity CRP. They also assessed the importance of inflammatory and residual cholesterol risk across the range of on-treatment LDL concentrations. They found that the relative benefit of evolocumab for the prevention of adverse cardiovascular events was consistent, irrespective of baseline high sensitivity CRP. However, because patients with higher high sensitivity CRP levels had higher rates of adverse cardiovascular events, they also tended to experience greater absolute benefit with evolocumab.
In an analysis of baseline high sensitivity CRP in achieved LDL cholesterol, the authors found that at first cardiovascular event rates were independently associated with both LDL cholesterol and high sensitive CRP. Event rates were lowest in patients with the lowest hsCRP and LDL cholesterol, supporting the relevance of both inflammatory and residual cholesterol risk.
The next paper provides further evidence that residual inflammatory risk, as measured by on-treatment high sensitivity CRP, remains an important clinical issue in patients on combination statin and PCSK9 inhibitor therapy. Dr Pradhan, from Brigham and Women's Hospital and colleagues, evaluated the residual inflammatory risk among patients participating in the SPIRE-1 and -2 cardiovascular outcome trials, who are receiving both statin therapy and the PCSK9 inhibitor bococizumab, according to on-treatment levels of high sensitivity CRP and LDL cholesterol measured 14 weeks after drug initiation.
They found that among high-risk stable outpatients treated with moderate or high-intensity statins and PCSK9 inhibition, roughly one in two had residual inflammatory risk defined by an on-treatment high sensitivity CRP level of 2 or more mg per liters, and roughly one in three had values above 3 mg per liter.
PCSK9 inhibition was associated with a 60% mean reduction in LDL cholesterol but little change in high sensitivity CRP. Levels of high sensitivity CRP above 3 mg per liter were associated with a 60% greater risk of future cardiovascular events, corresponding to a 3.6% annual event rate, even after accounting for on-treatment LDL cholesterol.
Thus, PCSK9 inhibition, added to statin therapy in stable outpatients, does not lower high sensitivity CRP. Persistent elevations of CRP is associated with future cardiovascular risk in these patients, even after low levels of LDL cholesterol are achieved. If corroborated, these data suggests that inflammation modulation may yet have a role in the primary and secondary prevention of cardiovascular disease when LDL cholesterol is already controlled. Well, that wraps it up for our summaries. Now, for our future discussion.
In-hospital cardiac arrests are common worldwide and they're so important because they represent opportunities for us to improve survival. Now, yet, overall rates of hospital survival after in-hospital cardiac arrests remain poor and there is substantial variation across facilities. This may be surprising because we all seem to follow or should follow the same ACLS algorithms across the world and yet, there are different outcomes.
How do resuscitation teams, at top performing hospitals, for in-hospital cardiac arrest, how do they succeed? Pleased to be discussing this with a real star team in today's podcast. We have first and corresponding author of our feature paper, Dr Brahmajee Nallamothu. We also have Dr Steven Kronick, who is the chair of the CPR committee and both are from University of Michigan Medical School. We also have Dr Sana Al-Khatib, who is a senior associate editor of Circ, from Duke University. So, welcome everyone! Let’s go straight into it. Maybe starting with you Brahmajee, could you tell us what inspired you to perform this study?
Dr Brahmajee Nallamothu Thank you, Carolyn, for giving us the opportunity to talk about this study. I'm an interventional cardiologist here at the University of Michigan and typically, this isn't an area that interventional cardiologists are really greatly involved with. I became interested because I also, at times, I round in the cardiac intensive care unit, and that's a place where a lot of patients often times end up after they've had an in-hospital cardiac arrest at our institution and what I've noticed over the years, is the variability in care that would be occurring out there, and then also lots of gaps in the literature.
Over a decade or so ago, I started partnering with a close friend and colleague, Paul Chan, from the Mid America Heart Institute and we started to do a series of studies on how in-hospital cardiac arrest care varies across institutions in the United States and we published a number of articles that have been in really high-profile journals over the last 10 years, but the problem has always been that even though we could describe really well what was happening, we had very little understanding of why it was happening or how certain hospitals were seeming to outperform others in this really challenging situation.
We wanted to dive a bit deeper into the questions and reasons behind top performers doing so well and that's what brought us on to doing this study.
Dr Carolyn Lam: Great. You want to tell us a little bit about it? It's really very different from the other CPR studies I've seen. Could you tell us about it and what you've found?
Dr Brahmajee Nallamothu: Sure, so in the broader framework, it's a qualitative study and what I mean by qualitative is, we didn't really collect data either through surveys or through outcome assessments. What we did was, we actually went out and talked to people.
The study though was really focused on what people call a mixed methods approach. We didn't just randomly talk to different hospitals, we actually focused on hospitals that were at the top-performing levels. We also focused on some hospitals that were non-top-performing as well, to get some contrast between the two and when I said we talked, we did this in a very systematic and pretty rigid way.
We always had four interviewers go out to nine hospitals. We split them up, so we had two content experts and then two methodologic experts in qualitive studies, and we started to interview a bunch of people. In fact, we interviewed almost 160 people across these nine hospitals.
We interviewed everyone from CEOs and hospital leadership, down to boots on the ground, including both clinical providers and even non-clinical providers, such as spiritual care, security. We tried to get this comprehensive view of what was actually happening during an in-hospital cardiac arrest across these nine hospitals, and really the results were quite fascinating to us.
For someone, like myself, that's been in this space for ten years, I tell people I learn more talking to these nine hospitals than I have in the last ten years of looking at numbers on a spreadsheet. I really started to understand, for the first time, what was really going on, how these hospitals were dealing with these challenging situations because there's no bigger emergency in a hospital, and Steve, who we're going to hear from, we talk about this, but Steve has a great line about how when an in-hospital cardiac arrest occurs, that patient automatically becomes the sickest person in an institution and yet, we haven't set up systems that really build on how to handle that in the most consistent and positive way.
Dr Carolyn Lam: Oh, my goodness, I just love that line! Now, you have to tell us, so what's the secret? What's the secret of the succeeding hospitals?
Dr Brahmajee Nallamothu: What we found in general was, that resuscitation teams at top-performing hospitals really demonstrated the following features. They had dedicated or designated resuscitation teams. They really included the participation of diverse disciplines as team members during the in-hospital cardiac arrest. There were really clear roles and responsibilities of the team members that were set up right from the front.
There was better communication and leadership, actually, during these events and finally, in the training aspect, one of the unique things we found was, the top-performing hospitals seem to have a high rate of in-depth mock codes, that they used as strategies for getting their clinicians ready for these events.
Dr Carolyn Lam: As you were speaking I was just thinking through the experiences of in-hospital cardiac arrests that I've encountered, and you're right. These elements, though we don't talk about them much, make a huge difference. Steve, I am so curious about your outlook. I mean you must have attended a kajillion CPRs as chair of the CPR committee. Tell us, what do you think is the take home message for clinicians and hospitals?
Dr Steven Kronick: My field is in emergency medicine and as chair of the CPR committee, I have responsibility of overseeing how we respond to cardiac arrests in our hospitals. I think that many institutions spend a lot of time and effort looking at in-hospital cardiac arrests are managed, and how to improve on it. We're able to use data to help compare ourselves to similar institutions, but beyond the bottom line of either ROSC or survival to discharge, we've most relied on process measures to figure out what we're doing.
We're essentially flying blind, or at least not flying in any sort of formation when we do that. I think that this study validates some of the operational aspects of the arrest response, for those centers who use those and can help other decide where they want to direct their efforts. I think a good example that Brahmajee brought up, is this distinction we found between the use of dedicated teams, designated teams, or not having any organized team, and the impact that has on survival.
The use of these teams can mean significant use of resources but showing that it's associated with better outcomes help provide support for that concept and for those centers who might already use one of those models, it helps them to steer their efforts to improving the delivery or the efficiency of that model.
Dr Carolyn Lam: Yeah, and indeed. Congratulations to both of you, Steve and Brahmajee. I do think that these are novel contemporary data, at least the first that I know of. Sana, you handle the paper and recognize this. Could you tell us a little about what you think are the novel and important aspects?
Dr Sana Al-Khatib: I really have been a fan of this paper from the get go and yes, it doesn't have the quantitative analysis that the statistical modeling, most of us are used to. It is a qualitative study, but I think that gives it strength. It makes it unique. This type of research, it can really only be effectively done through a qualitative study that really has all the important aspects of a good qualitative study, so I do want to congratulate them. Clearly, a lot of work went into this, and I appreciate all their efforts.
In terms of the main findings, some of us might look at this data and say, well it's not surprising that those are the characteristics, or the features, of the top performing hospitals, but I felt like it was great, in terms of how the data were presented. Encouraging hospitals to adopt this. Giving them almost like a checklist of what they need to be doing to improve the outcomes of their in-hospital cardiac arrests, in terms of ensuring that they have designated resuscitation teams.
The whole idea about diversity of participants in these arrests, and making sure everyone has a clear role and responsibility. The whole idea of making sure that somebody takes leadership and you have clear and very good communication among the different people who are doing this and great training. In fact, these people were doing in-depth mock codes. I think that spells it out very nicely and gives a lot of the hospitals, hopefully, action items that they can implement to improve the outcomes these patients. I love this paper.
Dr Carolyn Lam: Sana, I love the way you put that. Checklist, and you know what I was thinking as Brahmajee and Steve were talking earlier? I was thinking blueprint, almost, of the things that we should have. So Steve, could I ask your thoughts. I mean, are you going to put some of these things into practice in your own committee and how?
Dr Steven Kronick: There are a variety of things we can do. Some of these things are a pretty high-functioning place, but still looking at recommendations that have been laid out and how we help modify those things. Though the example is the roles that people play at an arrest. We can certainly improve on assigning those roles, how people work together as a team, and then also, getting to work more as a team, so that when they are called upon to perform those duties, they can do it in a more coordinated way.
Dr Carolyn Lam: How beautifully put. I'm going to steal a couple of minutes at the end of this podcast. I really have to because it's so rare to have Brahmajee on the line today and he's the Editor-in-Chief of Circ: Cardiovascular Quality and Outcomes. Brahmajee, could I ask you to say a few words to our worldwide audience about your journal?
Dr Brahmajee Nallamothu: We are a kind of daughter journal to Circulation. We are a bit more unique than the others, in the sense that we aren't disease or subspecialty focused. We deal with, broadly, the issues around outcomes research, health services research, quality of care research, and really health policy. We publish an issue once a month. We have a broad interest in things that are really relevant to the community around outcomes research and health services research.
I will say that I really appreciate this because of the worldwide audience and reach, one of the big issues we've been very interested in is expanding our reach, from the United States to other parts of the world, and in fact, last fall, we had a global health issue, which was well received, and we received papers from across the world.
In fact, every paper in that issue was a non-US-based paper, and it touched on a number of things from issues around healthcare utilization in Asia to demographics and disease registries in Africa, and it was a wonderful experience, so I think it's a journal that we're excited about.
It was first launched by Harlan Krumholz, who has set a high bar and standard for us, and I think that my editorial team, which has been fantastic, has continued with that work. We would love to see papers from your readers and your listeners from across the world and excited about what that journal is going to be doing in the next five years.
Dr Carolyn Lam: Oh wow! That's so cool! Well listeners, you heard it right here, first time on Circulation on the Run. Thank you so much for joining us today. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore. This week features Circulation Global Rounds, a brand-new series of papers from all across the world that you are going to want to hear about, coming right up after these summaries.
The first original paper this week tells us that community trends and acute decompensated heart failure may differ by race and sex. Dr Patricia Chang from University of North Carolina in Chapel Hill and colleagues examine the 10-year rates and trends of hospitalized acute decompensated heart failure in the Atherosclerosis Risk in Communities or ARIC study, which sampled heart failure–related hospitalizations in four US communities from 2005 to 2014, using ICD-9 codes. They found that acute heart failure with reduced ejection fraction was more common in black men and white men, whereas acute heart failure with preserved ejection fraction was most common in white women.
Rates of hospitalized acute decompensated heart failure increased over time, with higher rates in blacks, and rising cases of preserved ejection fraction heart failure. Mortality rates were 30% at one year with a more pronounced decrease over time in blacks but generally did not differ by heart failure types. Whether racial differences may be related to age of onset comorbidities, or other community level and social economic factors, deserve further study.
The next paper is a population-based study identifying long-term outcomes and risk factors and children with hypertrophic cardiomyopathy. Dr Alexander from Boston Children's Hospital and colleagues examine the National Australian Childhood Cardiomyopathy Study, a long-term national cohort study with a median follow-up duration of 15 years. They found that the greatest risk of death or transplantation for children with hypertrophic cardiomyopathy was in the first year after diagnosis, with 14% of patients achieving this combined end point compared to 0.4% per year thereafter.
Risk factors for death or transplantation included symmetric left ventricular hypertrophy at diagnosis, Noonan syndrome, increasing left ventricular free wall thickness, and lower fractional shortening during follow up. The majority of surviving patients had no symptoms. Thus, children with hypertrophic cardiomyopathy who are alive one year after diagnosis have a low long-term rate of death or transplantation. Deaths from heart failure usually occur soon after diagnosis, whereas the risk of sudden cardiac death is ongoing.
The next paper is the first demonstration of a peripheral clock in the perivascular adipose tissue that could contribute to the homeostatic regulation of circadian blood pressure variation. Co-corresponding authors Dr Chang and Chen from University of Michigan and their colleagues used a novel brown adipose specific aryl hydrocarbon receptor, nuclear translocator-like protein 1 or Bmal1 and angiotensinogen knockout mouse model to demonstrate that local Bmal1 in perivascular adipose tissue regulated angiotensinogen expression
and the ensuing increase in angiotensin II, which acted on smooth muscle cells
in the vessel walls to regulate basal activity and blood pressure in a circadian
fashion during the resting phase. In fact, deletion of Bmal1 or angiotensinogen
in the perivascular adipose tissue resulted in a superdipper phenotype with
exacerbated hypotension during the resting phase. These findings imply that it
is possible that obesity could alter the perivascular adipose tissue peripheral
clock, thus promoting abnormal dipper phenotypes and increasing
cardiovascular risk. The results therefore inform the design of novel therapeutic
approaches for hypertension by targeting the perivascular adipose tissue
What is the net clinical benefit of oral anticoagulation for very elderly patients
with atrial fibrillation? Well, the next paper by first author Dr Chao, cocorresponding
authors, Dr Chen from Taipei Veterans General Hospital and Dr
Lip from University of Birmingham, addresses this question. These authors use a
nationwide cohorts study in Taiwan to compare the risks of ischemic stroke and
intercerebral hemorrhage between patients with and without atrial fibrillation,
all aged 90 years and above, from 1996 to 2011, and they also compared
patients treated with warfarin and non-vitamin K antagonists oral
anticoagulants, or NOX from 2012 to 2015 when NOX were available in Taiwan.
They found that even among these very elderly patients aged 90 years and
above, atrial fibrillation was associated with an increased risk of ischemic stroke
compared to patients without atrial fibrillation. Warfarin use was associated
with a lower risk of ischemic stroke, with no difference in intercerebral
hemorrhage risk compared to nonwarfarin treatment. The use of warfarin was
associated with a positive net clinical benefit compared to being untreated or to
antiplatelet therapy. Compared to warfarin, NOX were associated with a lower
risk of intracerebral hemorrhage, with no difference in the risk of ischemic
stroke. Thus, oral anticoagulation may still be considered for
thromboprophylaxis in very elderly patients with atrial fibrillation, with NOX
being a favorable choice
The final paper provides insights into the mechanisms linking obesity and
cardiovascular diseases. Co-corresponding authors, Dr Kong and Wang from
Peking University Health Science Center and colleagues use a combination of
animal models and human adipose biopsies to characterize a new adipokine
named family with sequence similarity 19, member A5 or FAM19A5. This novel
adipokine was capable of inhibiting post injury neointoma information via
sphingosine-1-phosphate receptor 2 and downstream G12/13-RhoA signaling.
Thus, down regulation of FAM19A5 during obesity and loss of its vascular
protective function may trigger cardiometabolic diseases.
Well, that wraps it up for our summaries. Now for our feature discussion.
I'm just so excited about today's feature discussion, because we're talking about
Circulation going global. And I am just absolutely delighted to have with us, our
Editor-in-Chief himself, Dr Joe Hill from UT Southwestern, as well as our Senior
Advisory Editor, Dr Paul Armstrong from University of Alberta. So Joe, could you
start by telling us a little bit more about your vision for the global outreach of
Dr Joe Hill: Thank you, Carolyn. As I hope our readers are aware, Circulation is a global
journal with a global footprint. We have editors distributed around the world in
16 countries and 10 time zones. And importantly, those editors all have an
equivalent role at the leadership table. Part of the reason for this is because
cardiovascular disease is now, as we are all aware, a global scourge. There are
no more final frontiers for cardiovascular disease. That said, the manifestations
of cardiovascular disease differ in different parts of the world. In the developed
world, and the developing world, for example, the way cardiovascular disease
manifests itself can be very different. And at the same time, the way in which
the disorders are tackled are different. The way we tackle heart disease in the
West can be different than it is in the East, for example. And there are
important initiatives that have emerged in different pockets of the world, best
practices that we need to understand better. What can we all learn from the
way in which cardiovascular disease manifests itself around the world and it's
being addressed around the world?
Dr Carolyn Lam: Joe, you had me at hello. I remember that when you first took over as Editor-in -
Chief and I heard you say this, I was just floored, because coming from
Singapore and all our listeners out there in Japan and China, we just really
appreciate that global outlook. So thank you, on behalf of us all. Tell us a bit
more about this new initiative then for the journal.
Dr Joe Hill: I will tell you in broad strokes, that Paul Armstrong, a noted clinical trial is from
Canada, who is a household name in the cardiovascular world, he and I cooked
up a scheme that Paul will describe, where we will reach out on a regular basis
for insights from various different countries, ultimately, circling the globe
progressively over time. And I will defer to Paul to tell us more about the
Dr Paul Armstrong: Carolyn, it's an exciting initiative and as someone a little long in the tooth, but
still believing that you can teach an old dog new tricks, I would point out that
Circulation is almost 70 years old, and it has staying power. And one of the
reasons that it has staying power is because it is capable of reinventing itself,
and so I was attracted to help out again, from the editorial process, given Joe's
vision and leadership and the excitement around the reinvention that you've
described, to get involved with this initiative. And I was inspired, of course, by
the fact that those of us who do clinical trials appreciate that a lot of different
ideas, a lot of different cultures and perspectives are brought to a collaborative
table. And I'm thinking back now, Carolyn to three years ago, when you and I
first met enjoying courses as part of a trial in heart failure, which involves 43
countries, 800 sites, it will be 5000 patients centers, we've traveled separately
and together around the world, convincing people that there are unmet needs
in heart failure and other parts of cardiovascular disease, we learned that the
approach to standard of care, the rigor which is applied, the exquisite
sensitivities around differences that are meaningful, and the tricks that some
investigators and countries use that we can all I think, learn from has been very
So I think in this initiative, we want to have thought leaders. And we've already I
think, commenced and have two outstanding leaders from Japan and India to
come forward in the first two quarters of this initiative. Tell us about the
regional epidemiologic features, cardiovascular disease in their regions, what
the most important challenges are, what their best practices are, that you're
alluded to, who provides cardiovascular care and what the impediments are to
progressing because we think if we listen and learn as essentially knowledge
brokers, because welcome to Circulation, we can facilitate raising the level of all
of the boats in the water and potentially make new partnerships and do a better
job. So I'm excited about this. I'm delighted that Joe was receptive and really
look forward to working with him and some of these terrific people around the
world, you included who brings such a unique and important perspective from
which we can all learn.
Dr Carolyn Lam: Oh, I love that so much Paul. Thanks for putting it that way. International
knowledge brokers, that's what we hope to be. Isn't that fabulous, just an
opportunity to learn from each other, everybody having stuff to bring to the
table? Tell us a bit more though, what are you looking for in these papers?
Dr Paul Armstrong: We have some guidelines. But as Joe insists we're not going to be formulaic.
We're going to allow diversity of approaches. We're going to invite a thought
leader and hope that that thought leader might invite one or two others, we
want to limit it to three co-authors. We want obviously some insights into how
cardiovascular health professionals are being trained, what research
infrastructure exists, and how they access the literature, how do they read
Circulation, how do they read other journals, and are there collaborative ideas
that they've developed to their neighbors to the East and West that may be
could be broadened? Are there unmet needs that they've indicated similar or
different from those in Western Europe, South America? We've got about seven
or eight points of light that we hope to illuminate in the course of this exercise.
And the prospectus that's laid out in an editorial that Joe and I collaborated on
that I believe, Joe, is going to come out in early July.
Dr Joe Hill: That's exactly right, Paul. And I would just echo exactly what you said that just
the opposite of a formulaic, cookie cutter approach. We want to leverage the
beautiful diversity of our world. The different approaches that people take to
attack this scourge that is keeping a humble approach to tackle instead of the
visas that is humbling bar none. There is nothing that is more globally important
than the continued growth and expansion of cardiovascular disease. And
importantly, we can all learn from each other. There are exciting initiatives that
I've learned about in South America and in pockets of Europe and in Asia, and in
the Middle East that we can all benefit from, and we want to shine a bright light
on that. These pieces will be relatively short. They will be in our Frame of
Reference section, so 1200 words or so, so that they are accessible so that
people, you know, feel that they can carve out, you know, four minutes in their
busy day to read what cardiovascular disease looks like, as Paul said, our first
ones will be from Japan and India, and we plan to reach out to South America
and to the Middle East, and just continue on around until over the course of the
next number of years, we've touched virtually every country in the world.
Dr Carolyn Lam: And that's huge. And are there any specific types of cardiovascular disease that
you might be looking to focus on?
Dr Joe Hill: You know, I don't think so. One of the points that I have made and learned is
that in the West, in the developed world, cardiovascular disease increasingly has
become a chronic disorder where more and more people, over the course of the
last six years are surviving their acute coronary syndrome, their tachyarrhythmia
events, and they are developing chronic disorders like heart failure, whereas in
the East, it is the atherothrombotic manifestations that have both MI and stroke
that are expanding rapidly. So given that the face of cardiovascular disease is
different in different parts of the world, different strategies have to be
leveraged to address that, and we want to learn about that.
Dr Carolyn Lam: I would love to have you both come talk again, when we receive some of these
papers and just reflect on the things that we're learning. Paul, did you have
anything else that you wanted to add?
Dr Paul Armstrong: I think, Carolyn that hits the high spots. I suppose we should mention diabetes
and obesity and the expanding epidemic that seems to effect some regions such
as India, in the Middle East, even more than other areas, but I think this is going
to be great. We're gonna have some fun and learn and exciting and hopefully it
will catalyze better care and better thinking around this enemy that we all face.
Dr Carolyn Lam: Listeners. You heard it right here, Circulation on the Run. I'm sure you're excited
as I am about this. You have to read the editorial. It's a fantastic read.
Thanks for joining us today. And don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, Associate Editor from the National Heart Center, and Duke National University of Singapore. And I am joined today by our Editor of Digital Strategies, Dr. Amit Khera from UT Southwestern, as well as three wonderful fellows in training. Yes, you've guessed it, it's our FIT Podcast and I'm just so thrilled to be here again.
Dr Carolyn Lam: Amit, any words of introduction before we start?
Dr Amit Khera: Thank you Carolyn. I think, for both of us, this is our favorite podcast, or two podcasts, that we do, a year. It reminds us of how bright the future is, with superb cardiology fellows in training around the country, and it really is a testament to how important we find fellows in training, to Circulation, to our mission, and how much we learn from them.
So we're really excited about this group, today, and thank them for participating.
Dr Carolyn Lam: Absolutely. So, why don't we start, now, with ladies first? Let's hear from Dr. Elizabeth Hill.
Dr Elizabeth Hill: Thanks for having me today. My name is Beth Hill, and I'm a first year cardiology fellow at Scripps Clinic, in La Jolla, California. I've a particular interest in sports and exercise cardiology, which brings me to the article I picked today about sudden cardiac death and hypertrophic cardiomyopathy, hot topics in the field and in general.
And so, today, I'm excited to be discussing the EVIDENCE HCM study, looking at the hypertrophic cardiomyopathy of risk, sudden cardiac death model.
Dr Carolyn Lam: Nice. So tell us a little bit about what really struck you about the paper and, perhaps, how that may apply to where you practice?
Dr Elizabeth Hill: What I really liked about the paper is that, when I see patients in clinic with hypertrophic cardiomyopathy, prior to having this risk stratification tool, we didn't really have a way to objectively risk stratify our patients with hypertrophic cardiomyopathy and really guide the discussion about who may benefit from an implantable cardiac defibrillator or ICD. And so, I've been using this a little bit with my patients. While it hasn't made it fully into the AHA or ACC guidelines yet, I'm using it as a tool.
Dr Carolyn Lam: Great. You know, these are seven risk factors, isn't it? I'm always struck by that survival curve that really shows that those with a predicted 6% risk stand out. Is that what you use, as well, to guide your decisions?
Dr Elizabeth Hill: Yeah. I think, as the authors noted, they picked this somewhat arbitrarily so that they could study their risk model. But I think what they found is that it seemed to fit well with the observed high risk of sudden cardiac death cohort, such that those that were seen and observed, about 9% risk of sudden cardiac death in five years, were in that greater than 6% cohort. So I think that population should receive ICDs, and that is one factor that I used to guide my decision making as well.
Dr Amit Khera: Beth, this sort of interest that you've had for a long time, in sports cardiology, I've noted you've done some prior work in EKG screening and other screenings. In terms of this article specifically, as you pointed out, this is a really helpful tool because I still remember back when I was a fellow in training, there was, sort of, this thought that everyone was high risk with hypertrophic cardiomyopathy, and I think we realized that's not true at all. The overall incidence of sudden death was only 2.4% in this cohort.
The question I have for you, in terms of application, is, as Carolyn pointed out, these are reasonably simple variables, but as we sometimes are now using cardiac MRI and genetics and other more advanced tools, where do you think they fit in, in the current paradigm, since this is a bit of a more simplistic score?
Dr Elizabeth Hill: The seven risk factors they put into this tool were noted to be independently associated with an increased risk of sudden cardiac death, and those are well known factors, entricular tachycardia, maximum wall thickness. But I really do think that other factors will come into play soon and are part of my discussion, and colleagues' discussions, including the late gadolinium enhancement on MRI, genetic factors, and I really think this may be a place for tools like machine learning. These authors, O'Mahoney and colleagues, they really did, kind of a tour-de-force, going back to the 1970s, but there is still a decent amount of data missing. So maybe we can partner with the machines and help them go back into these records, a little bit more effortlessly, and look at genetics, maybe some wearable device data, and really refine our risk stratification tool moving forward. But that's definitely something I use in risk stratification in some of my intermediate risk patients.
Dr Amit Khera: Those are great points. I think your point about machine learning and novel algorithms will definitely take foot in the future.
Maybe a follow-up, again, given your background interest, I think it's a trade-off where we're trying to, of course, avoid sudden death, but you also don't want to overtreat. Especially, when you think about athletes getting ICDs and how that changes, or anyone, for that matter, about maybe telling someone they're at high risk, or giving them an ICD when perhaps they don't need it. I guess that comes to, what's the threshold? Here they use 6%, but that ends up being a bit arbitrary, in terms of what threshold we use. And how do we decide, when we talk to our patients, about what threshold's a right threshold to apply an ICD?
Dr Elizabeth Hill: Yeah. That's a great question. Like you mentioned, these devices come with inherent risks, such as unnecessary shocks, increased risks for infection, and sometimes there's restrictions with athletic sport, although that's been changing recently.
But, I think that's where the shared decision-making process comes into play, where you put current data on the table with the patients and, perhaps, their families as well, and have a risk-benefit discussion. Perhaps gather a little bit more data about the patient, maybe follow them over time, but I guess I wouldn't jump to put an ICD in, in every patient and, especially, the lower-risk cohort. And what number that is, I'm not quite sure. Here they say maybe less than 4%, but, again, somewhat arbitrary, I think.
Dr Carolyn Lam: Thanks Beth. I mean, as Amit said, it's just so inspiring to see how the papers are being used in practice. Really loved those perspectives.
Now, from sunny San Diego all the way to snowy New Zealand. We have Dr. Mesfer Alfadhel. And Mesfer, tell us a little bit about yourself, and the paper that you've chosen?
Dr Mesfer Alfadhel: Thank you very much. I'm thrilled to be part of this podcast. I'm a second-year cardiology fellow-in-training at the Needham Hospital, in Needham City, New Zealand, where it's snowing at the moment. I'm also a clinical lecturer at the University of Otago School of Medicine. I do have great interest in general cardiology, as the rest of my colleagues, but also am passionate about interventional cardiology and structural heart disease.
The paper I've chosen is really quite relevant to everyone in cardiology, and perhaps extends to other colleagues in other health professions impacted by automated external defibrillator use on survival and functional outcomes in shockable observed public cardiac arrest. The aim of the study was to determine the association of bystander automated external defibrillator use, the survival and function of outcomes in shockable observed out of hospital cardiac arrests. The study was from 2011 to 2015 and the Resuscitation Consortium prospectively collected detailed information on all cardiac arrests at nine regional centers, six in the United States and three in Canada.
They also found that among nearly 50,000 out of hospital cardiac arrests, 8% were observed public out of hospital cardiac arrest, of which 61% were shockable. Overall, a remarkable one in five of shockable observed public out of hospital cardiac arrest were bystander shocked. Now the bystander automated external defibrillator observed, shockable observed public out of hospital arrests were associated with increased odds of survival and full or near full functional recovery almost 2.6 and 2.7 odds ratio than when compared to emergency medical service defibrillation. What's also interesting is that the longer the wait for the emergency services, the higher the benefits from a bystander observed shock.
Dr Carolyn Lam: You know, Mesfer, I appreciate that you chose this one as well. What struck out to me immediately was that more than 60% of out of hospital cardiac arrests were shockable. And when we think about the number of lives that could potentially be saved, therefore, that's quite astounding, isn't it? But can I ask you something? So these are in the US and Canada, how applicable do you think this is to New Zealand?
Dr Mesfer Alfadhel: We do have a small population, just over four million. The number of cardiac arrests here is around 2,000 out of hospital cardiac arrests. And I think probably half of them in the latest reports were shockable. The emergency response time in the urban areas is around six minutes, which I think is acceptable, but we have about 20% of population living in rural areas. And the emergency response time exceeds 10 minutes almost all the time. I think that probably a group that we need to direct intervention to in New Zealand.
Dr Amit Khera: It's really an important article. I should say that June for the American Heart Association is AED and CPR month so great choice to remind us of the value of these and especially, the one thing that was amazing, obviously this is an observational study, but the absolute change, not relative, was about 14% meaningful recovery and so that's quite impressive in terms of the number needed to treat if you will. Maybe an adjunct to Carolyn's question is, when we think about strategies to enhance bystander AED use for strategies, essentially get the AED there faster. As you know if the EMT time was not delayed it wasn't necessarily better for the bystander.
We had a paper in Circ sometime last year looking at drones and then also geocoding and other people in some countries have looked at apps where you essentially can train a group of people and then they can be texted for a sudden cardiac arrest in their area. I'm curious about any creative things, there's always training and AEDs, I think in this place it was public areas in industry, but what do you think are some creative things or things that we need to be doing to help enhance the ability for bystander or early AED use.
Dr Mesfer Alfadhel: I think this is one area in medicine in general that where technology is really going to advance how we deal with this problem. There's an app that's available, it was launched in the UK a few years ago and it’s become available in New Zealand in the last two weeks called, the Good SAM. SAM stands for smartphone activated medics. And it's become available in New Zealand two weeks ago and I downloaded it and still yet wait for it to be activated. And the way it works is you can activate a medical emergency using the app and it dials the emergency response but what it also does is it activates the nearest three people with CPR training nearest to you and it tells you how far they are from the emergency. Now if you don't have the app and you call 911 or the equivalent, the operator can activate it to the nearby personnel who have that experience. And I think it's going to reduce the time markedly.
Now the other end of the question where some of what strategies could be used I think we had a good report from Denmark where they made changes in 2007 in Denmark and then followed by the rest of the country in 2010 where they made CPR or resuscitation education as compulsory at school but also when getting a driving license they made courses available for free that increased the number of defibrillators available in public places and they shared that information with public. They’ve redone, audited their work, and compared to prior to intervention prior to 2007 and after that and they found an increase number of using the AEDs increased from somewhere around 2% to 15%, which is really encouraging. I think we are following Denmark in that regard probably at slower rate.
Dr Amit Khera: Thank you those are excellent insights.
Dr Carolyn Lam: Amit, don't you see that I just love learning from these fellows during these podcasts. We should do more of these. This is awesome.
Dr Amit Khera: I completely agree.
Dr Carolyn Lam: Thank you Mesfer, enjoy the skiing. But now from snowy New Zealand we're going all the way to Nashville Tennessee. Welcome Dr. Vineet Agrawal. So tell us a bit about yourself and your paper.
Dr Mesfer Alfadhel: So my name is Vineet Agrawal. I'm a second-year cardiology fellow at the Vanderbilt University Medical Center. My background is as a physician scientist and as a general cardiologist. My long-term goals are in understanding mechanisms underlying heart failure with preserved ejection fraction.
With that in mind I was really taken by an article that was recently by Margaret Redfield's group from the Mayo Clinic in Circulation, titled “Global Pulmonary Vascular Remodeling and Pulmonary Hypertension Associated with Heart Failure and Preserved or Reduced Ejection Fraction.” I found this article to be a very interesting, hypothesis-generating article.
In a nutshell what they did was they took an autopsy cohort of patients in the Mayo Registry and those who had heart failure with both preserved and reduced ejection fraction, normal controls, and those who had a primary pulmonary venous occlusive disease, and looked at the lung specimens of these patients. And interestingly what they found was there was a significant amount of pulmonary venous remodeling that had occurred in patients who had both preserved and reduced ejection fraction. This correlated not only with their right heart cath findings, so those who had elevated pulmonary pressures and elevated transpulmonary gradients, but also differed from the primary pulmonary venous occlusive disease in the sense that the histologic appearance of these vessels was quite different.
And while as an autopsy study this is not necessarily an article that would immediately change practice, what I think it does do though is it forces us to think about these conditions in a different context and particularly with an eye towards future therapeutics. Heart failure with preserved EF as a disease, as I'm sure we all know, is sorely missing therapies that could alter the disease progression and potentially even alter mortality in these patients. And this article in my opinion really sheds light on at least anatomically a new location for us to think about as a therapeutic target when we try to better understand this disease and find therapies for these patients.
Dr Carolyn Lam: Vineet, can I just say you're singing to the choir here. I'm such a fan of this work as well for obvious reasons. But hey, could I ask you, in your clinical practice, do you see a lot of these patients with HFpEF and pulmonary hypertension and wonder how to treat them? And along those lines, how has this paper helped you think about these patients more?
Dr Mesfer Alfadhel: I would say when I first started residency as a medical student this was not necessarily a condition that was really something that I had learned much about or felt like I had been exposed to; however, as a resident I felt like most of the patients, or at least half of the patients, I was seeing with heart failure had a component of diastolic heart failure or they had a preserved EF but very symptomatic from the standpoint of heart failure. And I struggled to treat them, particularly in some part due to the fact that many of the risk factors that contribute to HFpEF, diabetes, uncontrolled hypertension, obesity, are chronic problems that are difficult to manage as a clinician regardless.
And second because I feel that there just weren't any data to support any treatments that we were pursuing at the time and so we would try and apply what we had learned in other types of heart failure to these patients with limited results. If I could talk about what I think this article may change in terms of my practice today, one thing that we've always thought about in terms of pulmonary vascular remodeling in heart failure is that it's just a passive process that as fluid builds up you back up into the lungs and as the fluid builds up and backs up into the lungs you get remodeling.
I think one thing that this article shows is that it may actually be a bidirectional process, which would suggest that perhaps we may need to reconsider looking at pulmonary-specific therapies in this population. But more importantly I think it does confirm that chronic elevating filling pressures do have an effect and a deleterious effect on the pulmonary vasculature. Particularly when you look at other trials such as the CardioMEMS trial, the CHAMPION trial in which the data pretty convincingly showed that as clinicians we don't do the best job of reducing left-sided filling pressures in our patients with heart failure as much as we think we do. This article really drives home the point to me that I really need to make sure that when I see these patients that I'm doing everything I can to reduce their left-sided filling pressures because the consequences of not doing so can affect the lungs, which can then in turn affect the heart as well.
Dr Carolyn Lam: Vineet, that's really words of wisdom. Couldn't agree more. And these are the first sort of autopsy, histological evidence that we have, which is so important. I think if I could just add a couple of perspectives too, it makes me think about making sure that I rule out PVOD in these patients sometimes. We now keep thinking about HFpEF we forget that we need to also rule out PVOD and the other thing much as we now think about not just the filling pressures but the remodeling it's good to note that they found it more in the venous than the arterial system, which also comes therefore with a warning message that we can't just extrapolate I suppose all the PAH therapies that we know about. What do you think about that?
Dr Mesfer Alfadhel: I absolutely agree with that. It's really interesting that all of our therapies from heart failure standpoint and from a PAH standpoint have focused on the myocardium, the neural hormonal cascade, and then the arterials. The pulmonary main artery and arterials. I don't think anyone really understands the biology of pulmonary veins and yet they're actually a pretty significant part of our everyday practice in cardiology. Pulmonary veins are thought to be the source of atrial fibrillation. We look at pulmonary vein inflow when we evaluate patients with echoes. And yet we understand so little about the biology and the mechanisms by which pulmonary veins are affected in both diseased and healthy patients.
I think this article for that reason raises a number of very interesting questions and may potentially change the way we think about these patients.
Dr Carolyn Lam: I keep learning, Amit, this is awesome. I could go on forever so you better stop me.
Dr Amit Khera: I should probably just be a fly on the wall. You must know Carolyn is a HFpEF, HFrEF aficionado and you guys should have a side call for another hour after this. But I do have one, maybe orthogonal question which is, it's interesting because if you look at how insights were made, they're made off areas I would argue at least that we don't, modern environment uses much which is the autopsy and probably to a large degree hemodynamics as much as probably in the old days although that's changing. I'm curious in a fellowship training program your exposure to autopsy and kind of current in-depth hemodynamic-type training, what's your experience?
Dr Mesfer Alfadhel: Our experience with looking at pathological slides, getting under the microscope, seeing tissue first hand, is somewhat limited in our fellowship training program. I would say in certain subspecialties like our heart failure, advanced heart failure subspecialties we do get a chance to see more myocardial biopsy specimens, but I think increasingly the focus has been on noninvasive methods by which we can assess some of these same things that we used to do, use the microscope for. Invasive hemodynamics I think similarly we get a lot of experience in terms of spending time in the cath lab but I do kind of wonder if we don't have the same in-depth training that we used to have in understanding all the nuances of hemodynamics that used to exist in the past.
Certainly, I think that while that's partially a reflection of the way and the direction in which medicine is heading, there is a little bit that's potentially lost there. That said, while we have the benefit of manuscripts like this that does do in-depth hemodynamics and looks at autopsy samples from a clinical standpoint, if we were to ever try and understand this in a larger population I think we would be required to try and find a way to noninvasively or maybe through potentially invasive hemodynamics better study this in live patients.
Dr Amit Khera: Appreciate that answer and I'm just for all of you, this has been outstanding. You all have served as incredible expert discussants. I know Carolyn already said it multiple times but we've learned a ton about each of these articles and great to see how they come alive and are used in practice and how they're applied in your own thinking and specifically as fellows in training with these have meant to you. We thank you all for joining us and it's really been a fantastic experience.
Dr Carolyn Lam: Amit, I can only echo your thanks and thank you listeners for joining us today. Fellows out there you are so important to us. Please, please apply to join us on the next FIT podcast as you can see it's really fun.
Don't forget to join us again next week.
Dr Carolyn Lam: Welcome to Circulation on The Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. This week's issue is so special. It is an autopsy issue. I think it's actually the first of its kind in the history of Circulation. I am so pleased to have with me today Dr Jeffrey Saffitz from Beth Israel Deaconess Medical Center, who's the content editor for Pathology for Circulation and the guest editor for this entire autopsy issue. Welcome, Jeff.
Dr Jeffrey Saffitz: Thank you.
Dr Carolyn Lam: We also have Dr Lee Goldman from Columbia University Medical Center who wrote a beautiful perspective piece on autopsy. Thank you and welcome, Lee.
Dr Lee Goldman: Morning.
Dr Carolyn Lam: Jeff, could you start us off? I mean, an autopsy issue. How in the world did this come about?
Dr Jeffrey Saffitz: I think it really began by coincidence. The journal received submissions from several authors, each involving studies of autopsies, and the editors approached me and asked if we might consider grouping them together in a special issue focused on the role of the autopsy and cardiovascular medicine. I thought that would be a very interesting idea and this evolved into actually something much greater. Two additional papers came in focusing on the autopsy and I think looking at these papers in the aggregate, they represent what we can now consider to be the contemporary utility of the autopsy in understanding the way cardiovascular disease works. So I was particularly pleased that the editors agreed to group these papers into a single issue focused on the autopsy. We were really delighted that Lee Goldman agreed to write a perspective. He has had a longstanding history of studying the role of the autopsy and I hope the readers will find this to be a really interesting and useful issue which will, I hope, chart the course for future discovery.
Dr Carolyn Lam: Just listening to you, I love the way you say it's a contemporary look at autopsy. I mean, we covered things like molecular genetic, proteomic, autopsies, even like electronic autopsies using device. That's really cool. Lee, thank you again for sharing your time and incredible perspectives with us. The long history of autopsy. Do you think it's still necessary now?
Dr Lee Goldman: Maybe give some perspective. I first got involved in this a number of decades ago, when as a junior faculty member, I was assigned to be on the medical audit committee of the hospital where I saw patients as a cardiologist. And two of the senior people in the committee got into a debate about whether autopsies were still important given the advent of CT scans and other modern diagnostic technology. And to listen to them debate for 15 or 20 minutes, I finally had the temerity to pipe in and say we can actually study this, and so we did. We looked at autopsies in three different decades: 1960, 1970, 1980, and much to everyone's surprise, I think found, A. that the rate of which autopsies found diagnoses that doctors had missed and for which treatment would almost certainly have prolonged life was about 10 percent, and it was 10 percent, 1960, 10 percent, 1970, 10 percent, 1980.
But the difference was that doctors were missing different diagnoses. The things that got missed in 1960, and where autopsies showed there were being missed led to better diagnostic approaches and those things were rarely missed in 1980. But since people stayed alive longer, they got new things that we didn't really know much about in 1960. A big difference, fewer people missed heart attacks, pulmonary emboli, and things of that sort, but far more people had missed infections, especially fungal infections that were complication of multiple antibiotics or immunosuppressive therapies.
And so, as I followed this in 1980, if you will, to now, 2018, we find this gets recapitulated over and over again. Medicine moves forward, things we used to miss, we no longer miss, but people still die, and they still die from things that we don't always diagnose. We've done statistical analyses to show that probably the rate of misdiagnosis is going down a little bit, but it's still substantial and we still estimate that thousands of people each year die in the U.S. from things that are not what the doctors thought they had, and if that diagnosis had been made, the patient would have lived longer.
Dr Carolyn Lam: Lee, I just love that perspective. I have to say, it's really humbling. I mean, 1960s and so on would predate me as well, so I'm really humbled, and I love that reminder. Jeff, in fact, quite a number of our papers illustrate exactly what Lee said. We have four papers just dealing with sudden cardiac death, and that is still what diagnosis was struggled with. Could you tell us a little bit more about those?
Dr Jeffrey Saffitz: Yes, of course. I think we all recognize that sudden death remains a huge public health issue. We also realize that most people who die suddenly and unexpectedly don't do so in the hospital when they're being followed and monitored; rather, they die out in the community, and in many cases, these are individuals in whom major risk for coronary disease or other potentially lethal cardiovascular conditions was really not known. So I think it remains a major public health issue, and we still have a great deal to learn. So perhaps it's not surprising that four of the five papers involved autopsy studies of sudden death victims of individuals who died out in the community. A couple of them focused on sudden death in young people.
We know that these individuals often will have familial diseases, and the autopsy has been one mechanism for studying these individuals, so one of the papers from Michael Ackerman at Mayo Clinic, advanced the concept that they started many years ago, the so-called molecular autopsy in which they apply a whole exome sequencing in cases of sudden unexpected death in young people defined here as age under 40, and they identified some rare variants which were likely to be of potential pathogenic significance in sudden death. A related paper from Junttila et al in Finland looks at the finding of myocardial fibrosis in young victims of sudden death. They identified several cases in which that was the only structural change in the myocardium, and when they applied next gen sequencing, the identified variance that we typically associate with the familial non-ischemic cardiomyopathies, arrhythmogenic, dilated, and hypertrophic cardiomyopathy. But the key insight here is that we traditionally think of these diseases as having rather characteristic structural changes which we can recognize at autopsy. What they showed is that those structural changes might be limited to nothing more than some fibrosis. And so the key here is that this expands our potential opportunity to recognize these familial cardiomyopathies, and the overarching idea is we use the autopsy to serve the living. This is a way to gain information at autopsy that we can then use to help family members and other individuals by virtue of the insights gained at autopsy.
Dr Lee Goldman: When we did the estimates in my editorial, and I estimated that roughly 28,000 people die each year in America with diagnoses that doctors missed and for which treatment would have been different if they hadn't missed it, that's really based on, I'll call traditional autopsy methods, which are anatomical, include microscopic evaluation, include culture, but it's not historically included genetic testing. I believe, as these articles show, that the advent of genetic testing, which you could argue could have been done while the patient was alive, but we're not quite there yet in terms of testing everyone's genome, now help you autopsies find even more things that might've been missed. And as you just heard, also can have important information for the family. So, one of the issues you often get into in autopsies is what's in it for the family, and one of the problems here is that the pathologists don't get paid. For the family members, it's mostly an aggravation. The doctors are worried they're going to get sued if something that gets found. And so, to make this work you need to bring in some incentives. Doctors not getting sued if they find things because they should get credit for trying to learn more, some way to reimburse reasonably pathologists and hospitals who do the autopsies, and the understanding of family members that they not only will perhaps be more reassured about what happens to the loved one, but also may learn things that will affect their future, because certainly, these cardiomyopathies, instead of them being diagnosed, are familial and oftentimes will lead to testing and hopefully interventions in family members that'll be to their benefit.
Dr Carolyn Lam: Lee, what great comments about bringing this into the clinical perspective and I just love what you said, Jeff, about autopsy for the living. That is just a quotable quote. That's so cool. I noticed that you did ask Dr Judge to write an editorial specifically about bringing autopsies into the molecular genetic era. So I just want to encourage all our listeners to make sure you read that as well. But Jeff, back to you about the other two papers.
Dr Jeffrey Saffitz: Well, I think one that I found particularly significant is this idea that nowadays, patients come to autopsy with implantable cardiac electronic devices, and the point of this paper is that interrogation of these devices postmortem can provide really important information about the cause and timing of those deaths. I think the reality is that most pathologists who do these autopsies are entirely unprepared or ill equipped to do such interrogations, and so I think the point of this paper is simply to encourage pathologists who do these autopsies to develop partnerships and relationships with cardiologists who are able to get this type of information from these devices. And again, it not only provides information about what happened to that one individual and what the death was all about, but it provides important information to the family and potentially information that allows the family to recognize particular risks that might impact the living members. So I thought this was just another really interesting example of how information that is potentially available at autopsy may not be fully utilized, and I hope that this paper will have an impact in that regard.
Dr Carolyn Lam: That's great. Lee, did you have any perspectives on devices and its role in autopsy now?
Dr Lee Goldman: I guess that the point that I would just reinforce would be that diagnostic technologies, including the ability to monitor someone's heart rate, have helped us diagnose things that were missed in previous eras, but medicine is always pushing the frontier forward, and as long as we develop new therapies, develop new devices, there'll be new things to learn. I want to make one other point about what I'll call overconfidence in diagnoses. The published statistics for the accuracy of most diagnostic tests are based on what doctors think the diagnosis ends up being, not the autopsy, which is the ultimate gold standard. So, if you actually go through some not-so-complicated arithmetic, you'll find that many of the tests that we think are almost perfect at finding things really aren't because the people who die with those things found that autopsies that the test missed. There's something called a virtuous circle, there's also a vicious cycle. There's a bit of a vicious cycle here that if you don't do autopsies to be sure you aren't missing things, you become overconfident in the tests that you think are finding them, and therefore think you already know everything and don't need to do an autopsy. To me, in some ways, that's the most perverse result of the plummeting autopsy rate, which, by the way, can be linked directly to changes in how hospitals get accredited, that in prior years there was a minimal autopsy rate required for accreditation. When that was removed, not surprisingly, autopsy rates plummeted, and now, most autopsies done in the US are not done in hospitals because doctors aren't sure what's going on. They've done by medical examiners as part of the laws for autopsies least being considered and people who die without having had a medical attention to some degree.
Dr Jeffrey Saffitz: You are exactly right on all of these points. I'll just say this is the point of one of the other papers from Tseng et al. This was a prospective autopsy study of sudden death in the city and county of San Francisco, and what they showed here is that only about half of the deaths that were considered to be sudden cardiac deaths as defined by the conventional criteria actually turned out to be deaths due to a rhythmic disorder. So Lee's point is exactly right. Doctors think they know a lot of things, but they're not always right about that, and the autopsy is probably one of the best ways to bring some quality control to this, and to really provide, I think, objective data that often is the case flies in the face of what the previous thinking was, and I think this paper in this issue of Circulation really brings that point home very clearly.
Dr Carolyn Lam: Yikes. OK, so here I am, I practice in Asia, and I think the autopsy rates are even lower, so this is a great wake up call for me just listening. Let's switch gears a little bit. How about the paper by Dr Herrington? Now this goes to a proteomic bisection almost of maybe preclinical disease and atherosclerosis. Would you like to comment on that on, Jeff?
Dr Jeffrey Saffitz: In the perspective that I wrote with Gaetano Thiene, in addition to looking at the history of the autopsy, we looked to the future and just considered briefly what role will the autopsy play going forward, and I think the paper by Herrington is a great example of how we can use the autopsy to learn so much more about the way human disease works. The basic idea here is that something like coronary artery disease or atherosclerosis, we think of as being a disease that only involves the blood vessels, and we tend not to recognize it until it is rather advanced and clinically manifest, but we recognize that these diseases begin decades before they become clinically manifest. We really don't know how to identify the earliest antecedents, and without knowing that we really, I think, very much limit our ability to identify the disease way early before it becomes clinically manifest, and then be able to practice preventive measures and intervene to prevent the disease from occurring.
So, what this paper showed is that it's an application of high-throughput proteomics looking at coronary artery and aortic samples obtained at autopsy, and these authors identified particular changes in proteins that they then were able to show in a prospective independent clinical cohort were able to predict the development of coronary artery disease. So I think going forward, we are going to redefine our understanding of human disease by learning about its earliest expressions and its full systemic distribution, and in doing so, we'll be much better prepared to diagnose earlier and intervene and prevent disease. So I think this was a great example of how the autopsy can help in that effort.
Dr Carolyn Lam: I feel like we are going full circle in history and going back to learn about how to go forward. I don't know if I expressed that well, but I am just in awe of what I've learned from both of you. Thank you so much, Jeff, for putting together this amazing issue, and thank you so much, Lee, for sharing your perspectives. Thank you, audience, for joining us this week. You've been listening to Circulation On The Run. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. Today's feature discussion revolves around important hemodynamic and echo data from the reprise three trial, comparing the lotus and core valve transcatheter aortic valves in patients with high surgical risk. Can't wait? Well it's coming right up after these summaries.
The first original paper this week provide experimental data showing that the endothelium controls cardiomyocyte metabolism and function via notch signaling. Corresponding author, Dr. Fischer, from German Cancer Research Center in Heidelberg, Germany, and colleagues, studied fatty acid transport in cultured endothelial cells and transgenic mice with endothelial specific notch inhibition, or wild type mice treated with neutralizing antibodies against the Notch ligand. They showed that notch signaling in the endothelium controlled blood vessel formation and fatty acid transport in the adult mouse heart. Inhibition of Notch signaling in the vasculature led to expansion of the cardiac vasculature and impairment of fatty acid transport to cardiomyocytes. This resulted in metabolic reprogramming and heart failure.
Together, these data provide compelling evidence for a central role of Notch signaling at the coordination of nutrient transport processes in the heart. These findings help to explain how pharmacological inhibition of Notch signaling, for example, in oncology could lead to heart failure. The findings also help to identify the signals and molecules involved in endothelial transport capacity and show how these could offer new targets for the treatment of heart failure.
The next paper raises the prospect of new treatment options to combat ischemic heart disease and its progression to heart failure. Ischemic injury to the myocardium is known to trigger a robust, inflammatory response, which is an integral part of the healing process, although much effort has been directed at tempering the inflammatory response in hopes of achieving clinical gain. Major efforts have focused on individual cytokines, the complement cascade, and antibodies to adhesion molecules preventing leukocyte invasion.
In contrast, relatively little effort has focused on macrophages. Although macrophage transformation is known to be crucial to myocardial repair, the events governing this transformation are poorly understood. In today's paper, co-corresponding authors of the trial in Hill, from UT Southwestern Medical Center, performed an elegant series of experiments and showed that release of DNA from necrotic tissue during myocardial infarction, triggered in macrophages a recently described innate immune response known as the GMP-AMP synthase-stimulator of interferon genes pathway or cGAS-STING pathway.
This response in turn promoted an inflammatory macrophage phenotype. Suppression of the pathway promoted emergence of reparative macrophages, thereby mitigating pathological ventricular remodeling. These results therefore reveal for the first time, that the cytosolic DNA receptor, GMP-AMP synthase, functions during cardio ischemia as a pattern recognition receptor in the sterile immune response.
Furthermore, this pathway governs macrophage transformation, thereby regulating post injury cardiac repair. As modulators of this pathway are currently in clinical use, these findings raise the prospect of new treatment options to combat ischemic heart disease and its progression to heart failure.
Cigarette smoking is a well-known risk factor for atherosclerotic cardiovascular disease. However, less is known about the risk for heart failure. First author, Dr. Kamimura, corresponding author, Dr. Hall, from University of Mississippi Medical Center, and their colleagues investigated 4129 black participants without a history of heart failure or coronary heart disease at baseline in the Jackson Heart Study.
They examined the relationship between cigarette smoking and left ventricular strength and function by using cardiac magnetic resonance imaging. They found that current cigarette smoking status, smoking intensity in terms of cigarettes per day, and smoking burden in pack-years, were independently associated with higher left ventricular mass, lower left ventricular strain, higher brain natriuretic peptides, higher BNP levels and higher risk of incident heart failure hospitalization in blacks.
These relationships were significant after adjustment for coronary heart disease, suggesting mechanisms beyond atherosclerosis may contribute myocardial dysfunction and increased risk of heart failure in smokers. In summary, these findings suggest that smoking is associated with structural and functional left ventricular abnormalities that lead to heart failure in blacks and that smoking cessation should be encouraged in those with risk factors for heart failure.
What happens to the risk modifying effects of exercise in individuals with increased genetic risk of cardiovascular disease. Drs. Tikkanen, Gustafsson, and Ingelsson from Stanford University School of Medicine performed the study in about 500,000 individuals from the UK Biobank and reported and compared the association's objective and subjective measures of fitness and physical activity with prospective cardiovascular disease events and all-cause death.
They found consistent and robust inverse association, particularly between objective measures of fitness and physical activity and six cardiovascular outcomes and total mortality. Using genetic risk scores for coronary heart disease and atrial fibrillation, they showed that these inverse associations were present in each genetic risk category, suggesting that elevated genetic risk for these diseases can be compensated for by exercise.
The knowledge that lifestyle choices have substantial effects on disease risk could encourage individuals to initiate a healthier lifestyle to reduce their overall risk. In the longer term, identifying subgroup space on genetic risk that benefit most from lifestyle interventions, could help personalize preventive strategies for chronic diseases.
Well, that wraps it up for our summaries, now for our feature discussion.
Today's featured paper deals with transcatheter aortic valve replacement, which we are all going to recognize has rapidly emerged as a treatment of choice in inoperable patients and, it's a reasonable alternative to surgical aortic valve replacement in high- and intermediate-surgical-risk patients. However, the success of this technology is in large part due to the rigor with which quantitative echocardiography by core laboratories has been used to assess the native and prosthetic aortic valve function.
Today's feature paper gives us such important data from the REPRISE III trial, which compares the Lotus and the CoreValve transcatheter aortic valve in patients with high and extreme surgical risk. I'm so pleased to have the corresponding author, Dr. Federico Asch, from MedStar Washington Hospital Center, as well as our associate editor, Dr. Dharam Kumbhani from UT Southwestern. All right Federico, please help me here, so as a noninterventionist and a person who doesn't deal with all these different types of valves every day, please tell us what was the motivation of looking so closely at the echocardiographic data from REPRISE, because the REPRISE III trial results were already published?
Dr Federico Asch: The most interesting aspect of this analysis is really that there is a very methodic, blinded comparison of two different valves. The valve that is being tested and that the reason why Boston Scientific has sponsored the study, is the Lotus valve, the Lotus System is, if you want, a new valve that is not clinically approved in the United States yet, that basically, it's a completely repositionable bovine pericardial valve that comes in different sizes.
The three sizes that were tested in here are what we would call the small, or 23 millimeters, the medium, 25 millimeters, and the large, 27 millimeters. Each patient, at the moment of randomization, or at the moment of inclusion, were randomized to the small, medium, or large Lotus valve vs the clinically approved CoreValve, which is a Medtronic product. Obviously, this is taken as the control group because this is one of the valves that is widely clinically available nowadays in the United States and worldwide.
This is exactly the motivation here. On one side, to prove whether this valve was as good as CoreValve or not and whether it was as safe as the CoreValve as well, and that, the study was about. Every three patients that were randomized, two were randomized to the new valve, the Lotus, and one was randomized to the CoreValve.
An important note to make here is because the control arm included clinically available valves at the beginning of the study, the previous generation of CoreValve was used and then about halfway through the trial, the Evolut valve was the one being used, so there's two different valves on the CoreValve system that were tested in this trial while Lotus was a single earlier generation valve.
We focus here on the hemodynamic implications, that meaning, the gradients and the degree, if you want, of obstruction that these valves could have over time, and the amount of regurgitation that these two valves and how they compare to each other.
Dr Carolyn Lam: That's great. Could I ask if you had any hypothesis going in, because as I recall, the Lotus valve actually met the non-inferiority comparison, but it did have significantly higher rates of new pacemaker implantation and valve thrombosis, right? So, was that perhaps a hypothesis going in and what did you find?
Dr Federico Asch: So, the initial hypothesis of the trial overall was that this new valve was one that was designed to have less paravalvular regurgitation, which is something as you probably know, has been of significant concern in the cardiology world ever since the initial clinical trials for Tyler with Partner and CoreValves.
Patients with more significant paravalvular leak did have worse outcome over time, so, one of the main goals of this valve itself, was to prevent that paravalvular regurgitation. So, that was the initial idea behind this product I would say, not just the clinical trial and obviously, this clinical trial tried to prove that, indeed, as I mentioned before, the primary effectiveness end point was mortality, disabling stroke, and paravalvular leak, the main driver on the difference between the two valves there was indeed a much lower paravalvular regurgitation on the Lotus valve compared to CoreValve.
There was also lower stroke rate, but the most important difference was on the paravalvular aortic regurgitation. Of course, when you think of any of these devices, for them to be able to prevent paravalvular leak, they have to have some kind of skirt or cushioning around the valve, an adaptive seal, which in the case of the Lotus valve, that would prevent any flow around the stent, but one of the risks of that of course is that by trying to seal the valve, you're actually, you may be decreasing a little bit the effective orifice area, so it was actually very important to understand whether gradients with this valve were higher and whether the potential differences in the gradients did turn into any difference in clinical outcomes.
Dr Carolyn Lam: That is super clear now. What did you find?
Dr Federico Asch: I would say, the findings from a hemodynamic standpoint, we can briefly summarize them in two aspects of it. No surprise, the paravalvular leak was significantly lower for Lotus compared to CoreValve, and that was true for any of the three sizes, for the small, medium, and large size in all of them, the rate was significantly lower for Lotus. It was actually under 1% of the patients with moderate or higher paravalvular leak, as opposed to an average of 6.7% on the CoreValve, but on the other side of the spectrum, the gradients and the effective orifice area, and the dimensional index were all significantly better on the CoreValve compared to the Lotus.
The bottom line is, we have two valves that each of them has a specific strength. On one side, Lotus has less paravalvular leak. On the other hand, CoreValve has a better gradient profile than Lotus. I would say in two lines, that's the findings of this study. We did take these findings further and compared among different valve sizes and we saw that these differences were consistent at each of the valve size, so if we would compare the small Lotus with the small CoreValve or the large Lotus with CoreValve, the findings were very similar.
They were always significant, and what is important is that while there was a difference, both for paravalvular leak and for gradients and other hemodynamic parameters, the reality is that when it came to clinical outcomes, there was no significant difference among the two.
Dr Carolyn Lam: Dharam, you have to weigh in now as an interventional cardiologist, what does this mean to you.
Dr Dharam Kumbhani: First of all, Federico, congrats to you and Ted and the rest of the group. I think this is obviously a very important trial and I think this hemodynamics paper, I think definitely moves, helps understand the differences a little bit better, so I think this is a very valuable contribution. I think you said it exactly right. I think what is really interesting is that you have a significant introduction into the paravalvular leak, but yet you have, because of difference in valve design, one being annular vs the other being super annular, you have higher gradients with the Lotus valve compared with the CoreValve, so you wonder if the two differences can cancel themselves out in some way, because you don't see any difference in clinical end points at one year, and also, I guess, what we've learned from the Partner data and other CoreValve data is it would be really helpful to see how this evolves over time, whether there will be any late separation of the curves or just a long-term follow-up, whether that will still be important.
I think that is the really interesting insight that we glean from this analysis. I want to make two other points. I think the other interesting thing about the design of the Lotus valve, and probably having such a great seal for the paravalvular leak reduction and having higher radial strength, I would think, at the annulus, I suspect that that's probably also the reason why the pacemaker rate is higher with this, compared with CoreValve, so it's almost 30% in this trial. About 20%, 18% already had an existing pacemaker, so particularly I guess, as we move to lower-risk population, I think that will certainly, balancing the two and deciding probably one valve doesn't fit everybody and we may have to have strategies to figure out which may be the best valve for a given patient based on this.
The other point I'd like to make is the question about stents or valve thrombosis and I know that your group has been heavily invested in that research, because I know in the JAMA paper, there was a report of few valve thrombosis events and you also bring that home here in this hemodynamics paper. Is there anything you want to elaborate on that or any insights that you feel would be helpful for the next set of trials and next generation of the Lotus valve?
Dr Federico Asch: Yeah, you're bringing two very, very important points. Let me address the thrombosis one first. As you very well described, we have been working a lot on multiple different valves and understanding why this is happening. It's clearly something of concern. In this study in particular, we did not have data collected to detect subclinical thrombosis, which is what most of us have been talking mostly about over the last few years. The diagnosis of thrombosis here was not so clinical. These were patients that mostly, because gradients were going up, were detected. They were image ... there was one or two cases with TE and the other ones with CTs and then they were given anticoagulation and those results, and based on that is that the diagnosis of thrombosis was made. All those cases, nine cases, indeed, happen on the Lotus group. The CoreValve is one in that overall has shown to have lower rates of thrombosis in general and I'm not just talking about our own report. Our report was consistent with that.
That may be something related to the fact that it's a super annular valve and the flow through the valve may be better, if you want, but we don't know that. The rate of thrombosis, again, clinical thrombosis, in this case, for the Lotus valve was 1.5%, which is still low, but it's impossible to compare to all those new reports that are coming out because those are mostly subclinical, which is not the case here.
One could argue that if would have done CTs on every patient here at 30, 45 days, we would have found much higher rates in both valves, but we don't know that. We don't have the data to address that.
Dr Dharam Kumbhani: As I remember, almost all of them, I think seven out of eight of those reported, were in the 23 valve, right? They were not ... I think the larger valves ...
Dr Federico Asch: Exactly. There were nine cases overall, eight of them were on the small valve, on the 23 millimeters, and one was in the middle size, on the 25 millimeters. You are completely right.
Dr Dharam Kumbhani: I don't know what to make of that, but that was an interesting observation as well.
Dr Federico Asch: Yeah. It's interesting because when you look at reports of subclinical thrombosis, actually some of the reports suggest that this is more common in bigger valves than in smaller valves. Registries, I'm talking about, but that didn't seem to be the case here, but again, we need to understand the limitations. This was not a study geared towards detecting sub clinical thrombosis or thrombosis overall. These are just clinically reported cases that were analyzed thoroughly but they were triggered by some kind of clinical event, what's mostly an increase in the gradient.
That's all that I would make out of the thrombosis. I think there is definitely more that we need to learn about it. We know that both CoreValve and Lotus have been reported to have cases of thrombosis, but in general, CoreValve seems to be of all the type of devices, the one with the lowest incidents.
Dr Dharam Kumbhani: Maybe your studies will help in understanding the influence of hemodynamic profile, patient-prosthesis mismatch, to the risk of thrombosis. I think the interactions are not well understood. I think that will be very interesting going forward.
Dr Federico Asch: Exactly. And the other comment that I wanted to make, Dharam, regarding your first impression about the pacemakers and the gradients, a couple of observations that I want to make out of that, one is that the difference in gradients between Lotus and CoreValve seem to be the highest early and then over months, that difference seemed to get smaller and smaller, still significant though, even at one year, but one could argue that if, as we continue following up these patients, maybe the difference starts getting smaller and smaller to the point that to become irrelevant, but we don't know that. That is just the impression that we get at looking at the curves over time.
The pacemaker, obviously, as you can imagine, this is something that is of concern for everybody. It's a high rate, the newer Lotus generations are geared towards having lower paravalvular leak, like the head Lotus Edge and so we would expect that in the future that would be the case, but we don't know. The same way that it is important to mention that CoreValve has been addressing their initial concern, which was paravalvular leak.
I mentioned before that the control arm in this clinical trial included CoreValve classic, earlier generations from roughly half of the patients, and the paravalvular leak in that group was a little bit over 10%, while the second group, which was the Evolut R had already a much lower rate of paravalvular leak, but was still significantly higher than Lotus, but was definitely better.
I think what this points out to, is that all these devices are so early in their life, in their history, that all the efforts that each of these companies are making into fixing the specific problems that each of them have, really turn into a next generation that addresses more aggressively all these things. In the case of CoreValve, definitely the paravalvular leak is one and they are making very good progress in the care of Lotus, the permanent pacemaker is one and we expect in subsequent generations to improve as well.
Dr Carolyn Lam: It's been very enlightening for me and I'm sure for all our listeners. Thank you for joining us today listeners. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associated editor from the National Heart Center and Duke National University of Singapore. This week's feature paper reports results of the SWAP-4 study, which is the first study to evaluate the pharmacodynamic impact of the timing and dosing of clopidogrel administration when de-escalating from ticagrelor therapy. Extremely important take-home messages for clinicians looking after patients with coronary artery disease and a must listen to. Coming up right after these summaries.
In the first original paper this week, chondroitin sulfate, well known in the context of the monogenic disease mucopolysaccharidosis type 6 may actually represent a novel therapeutic approach for the treatment of general heart failure. First author Dr Zhao, corresponding author Dr Foo, from Genome Institute of Singapore studied changes in myocardial chondroitin sulfate in non-mucopolysaccharidosis failing hearts and assessed its generic role in pathological cardiac remodeling. They found that failing human hearts display an abundant accumulation of chondroitin sulfate proteoglycans in the extracellular matrix largely localized to fibrotic regions.
The main component of chondroitin sulfate glycosaminoglycan chains in human hearts was chondroitin 4 sulfate. TNF alpha was a direct binding partner of glycosaminoglycan chains rich in chondroitin 4 sulfate. Modification of the chondroitin sulfate chain with the recombinant human arylsulfatase B, which is an FDA-approved treatment for mucopolysaccharidosis type 6 that targets chondroitin 4 sulfate, actually ended up reducing myocardial inflammation and overall fibrosis in vivo. In two independent rodent models of pathological cardiac remodeling, this recombinant human arylsulfatase B treatment prevented cardiac deterioration and improved functional recovery. Thus, targeting extracellular matrix chondroitin sulfate represents a novel therapeutic approach for the treatment of heart failure.
The next paper focuses on the subcutaneous ICD, which is an entirely subcutaneous system that does not require intra-procedural vascular access or endovascular defibrillator leads or coils. Now the subcutaneous ICD has a novel mechanism of defibrillation and is associated with an increased energy requirement for defibrillation when compared to traditional transvenous ICDs. Thus, ventricular fibrillation or VF conversion testing at the time of subcutaneous ICD implantation is a class 1 recommendation.
Yet, what is the current adherence to this recommendation? Well, today's paper addresses this question from first and corresponding author Dr. Friedman from Duke Clinical Research Institute. He and his co-authors studied first time subcutaneous ICD recipients between 2012 and 2016 in the National Cardiovascular Database Registry ICD Registry to determine the predictors of use of conversion testing, predictors of an insufficient safety margin during testing and in-hospital outcomes associated with the use of conversion testing.
Results show that use versus non-use of VF conversion testing after subcutaneous ICD implantation in the US was more related to physician preference than patient characteristics. The study also identified several patient characteristics associated with an insufficient defibrillation safety margin. That included increased body mass index, severely decreased ejection fraction, white race, and ventricular pacing on the pre-implantation ECG. Use of VF conversion testing after subcutaneous ICD implantation was not associated with a composite of in hospital complications or death. These data may inform ICD system selection and a targeted approach to conversion testing.
We know that elderly patients are at elevated risk of both ischemic and bleeding complications after an acute coronary syndrome and display higher on clopidogrel platelet reactivity as compared to younger patients. Does prasugrel at five milligrams compared to clopidogrel reduce ischemic events without increasing bleeding in the elderly? Today's paper addresses this question from corresponding from corresponding author Dr Savonitto from Manzoni Hospital Italy and his colleagues.
These authors performed a multicenter randomized open label blinded end point trial comparing a once daily maintenance dose of prasugrel five milligrams with the standard clopidogrel 75 milligrams in patients more than 74 years old with acute coronary syndrome undergoing percutaneous coronary intervention. The primary end point was a composite of mortality, myocardial infarction, disabling stroke and re-hospitalization for cardiovascular causes or bleeding within one year. Enrollment was interrupted due to futility for efficacy according to pre-specified criteria after a planned interim analysis when 1,443 patients had been enrolled with a median follow-up of 12 months.
At this point of interruption, there was no difference in the primary end point between reduced dose prasugrel and standard dose clopidogrel. The results of this Elderly ACS 2 study therefore could not show overall clinical benefit of prasugrel five milligrams versus clopidogrel in elderly ACS patients undergoing early PCI.
The final study is the first to define the cellular and molecular mechanisms of cardiac valve inflammation and fibrosis occurring in the setting of systemic inflammatory disease. First author Dr. Meier, corresponding author Dr Binstadt from University of Minnesota used T-cell receptor transgenic mice which spontaneously developed systemic auto antibody associated autoimmunity leading to fibro inflammatory mitral valve disease and arthritis.
They identified a critical population of CD301b/MGL2 expressing mononuclear phagocytes that orchestrated mitral valve inflammation and fibrosis in this mouse model. They further demonstrated an analogous cell population was present in human inflammatory cardiac valve disease. Finally, they defined key inflammation molecules that drove mitral valve disease in this model, thus providing multiple potential therapeutic targets that are required for mitral valve inflammation and fibrosis.
Dr Carolyn Lam: That wraps it up for your summaries. Now for our feature discussion.
Searching between different classes of P2Y12 inhibitors including de-escalation from ticagrelor to clopidogrel commonly occurs in clinical practice. However, what are the pharmacodynamic profiles of this strategy? Well, today's feature paper is going to provide a lot of insights. I am so pleased to have the corresponding author of the SWAP-4 study, Dr. Dominick Angiolillo from University of Florida College of Medicine Jacksonville, as well as our associate editor Dr. Gabriel Steg from Hôpital Bichat in Paris, France. Dominick, now this is SWAP-4. That means there was a SWAP 1, 2, 3. Could you just paint the background and rationale for SWAP-4 and tell us what you found?
Dr Dominick Angiolillo: We performed this study on the background of a line of research that we've been conducting over the past number of years of switching antiplatelet therapies. There's so many different types of switches that can occur and one of them is that which is defined as a de-escalation which is that from a more potent P2Y12 inhibitor to a less potent and one of those that occur frequently in clinical practice is the switching from a ticagrelor to clopidogrel and this was essentially the rationale for conducting the SWAP-4 study.
Now I want to start off with saying that the reason for doing this study is not to advocate switching because we always recommend that individuals follow guideline recommendations but we performed this study because we wanted to provide clinicians with some additional insights that if you're going to switch particularly from ticagrelor to clopidogrel, which would be the modality which is associated with, put it this way, with the smoothest transition one drug to another.
This is the rationale. What we did was do a pharmacodynamic, conduct a pharmacodynamic study taking patients who were on standard treatment with dual antiplatelet therapy aspirin and clopidogrel and they had a run-in phase with ticagrelor. And the reason why we took patients on the back part of aspirin and clopidogrel is because we then wanted to look at the effects after switching to compare it with a baseline. There have been some discussions about drug-drug interactions. And patients were randomized to either continue with treatment with ticagrelor to switch with a loading dose of clopidogrel, 600 milligrams 12 hours after last dose of ticagrelor. 24 hours after last dose of ticagrelor or directly switch with a maintenance dose. So, the randomization was into four groups.
Essentially to keep a long story short, what we observed was that when de-escalating from ticagrelor to clopidogrel we did see an increase in platelet activity obviously as expected. But the use of a loading was not able to mitigate this increase but there were no differences according to timing of administration of the loading dose clopidogrel 12 or 24 hours. We had anticipated in our study design that with the administration of the loading dose 24 hours after last maintenance dose we could have achieved a smoother transition, but this was not the case.
Nevertheless, the overall conclusions of our study are supported by the pharmacodynamic data in terms of you still achieve a better transition when you give a loading dose than without a loading dose. I was also want a little bit cautious and I think during the review process of the journal and feedback from the editors we kind of phrased in a very cautious way the suggestion for a drug-drug interaction, in fact we suggested because there are other ways to look into this phenomenon in more detailed manner. For example, doing some specific pharmacodynamic analysis which was not done in this study. Nevertheless, the take-home message from a clinical perspective remains unchanged.
Dr Carolyn Lam: Thanks so much, Dominick. That was a very important framing of the paper that you gave us at the start that this trial was not designed to try to say who should be de-escalated or not and that should be in line with the guideline recommendations and yet such an important just take-home message that if there is a need that the 600-milligram loading dose of clopidogrel should be used. You know, Gabriel, you've thought a lot about this and especially the drug-drug interaction question. What are your thoughts there?
Dr Gabriel Steg: Yeah, well first of I think this is an extraordinary, important study even though it's a pharmacodynamic study, which many clinicians might look at and then quickly read the abstract and turn the page I think this is actually one of the most interesting papers we've published in recent months. The reason for this is this is tackling a very common clinical scenario, which is having or desiring or wanting to de-escalate the intensity of platelet therapy after a PCI or ACS from a potent agent such as ticagrelor to a less potent agent such a clopidogrel. And as nicely explained in the paper, there are multiple reasons why this can occur.
A common clinical scenario is that cost is a major issue. Because of the cost patients or physicians may want to switch to clopidogrel, a generic drug as opposed to a branded drug. Another scenario which is fairly common is side effects. Either nuisance bleeding or maybe dyspnea with ticagrelor may prompt some physicians and patients to want to deescalate to clopidogrel. To a less intensive therapy which may not have dyspnea or may not cause as much nuisance bleeding. And finally, sometimes it's done on purpose because some believe that within a few weeks or months following PCI or ACS the benefits of more intensive patient therapy is less, the risk remains the same and therefore maybe we could proposedly de-escalate therapy to clopidogrel and get away with it and there have been a number of randomized studies and observational studies that suggested that this might be feasible although these studies have weaknesses. They're often open label. They're often fairly small and somewhat underpowered.
So, we don't have a definitive answer. Nevertheless, this happens on an everyday basis in most large clinical centers and we don't know exactly how to do it and what the best way to do it and I really want to credit Dominick's team for doing a rigorous series of investigations, including this one, which is the latest one but not the only one in trying to really map out how exactly we should as clinicians manipulate these agents to achieve the best safety and efficacy for our patients. And I think the message here is very clear. Yes, you can de-escalate but you have to be careful on how you do it. And I think you really need to use a loading dose, a 600-milligram loading dose of clopidogrel if you're going to deescalate from ticagrelor to clopidogrel to avoid a gap in protection that might be deleterious to patients.
That does not address all of the questions that are raised by de-escalation and as I pointed out I think outcome trial data are really of paramount importance here, but I think this really important because it has major practical implications for clinicians worldwide on how to do this. So, I think this is a great study. I really want to congratulate Dominick.
Dr Dominick Angiolillo: Thank you.
Dr Carolyn Lam: You looked at the genetic status as well. Could you tell us about your findings there?
Dr Dominick Angiolillo: We in the spirit of trying to perform the most comprehensive possible assessment we have also looked at the genetic background of our patients and in particular looking whether the presence of a loss of function allele for CYP2C19, which is involved with clopidogrel metabolism, could have affected the outcomes. And the reason why we did this there've been a lot of studies clearly showing that if you have a loss of function allele for CYP2C19 you do have higher levels of platelet reactivity. Therefore, we want to see if those carriers would have had even a greater increase in platelet reactivity. And again, we did all this in the spirit of really trying to define again this from a pharmacodynamic standpoint, if there could be any potential safety hazards with such an increase in platelet reactivity with the de-escalation.
When we did our analysis, we did not find any impact of a CYP2C19 on our data. However, I think it's important to underscore that we did not have too many patients with a loss of function allele so clearly the study was not designed or nearly closely powered to look into this assessment. So, I think that aspect does need to be interpreted with caution.
Dr Carolyn Lam: Thanks so much, Dominick. Were there perhaps caveats that clinicians listening in should pay attention to? For example, this study was conducted in stable patients with coronary artery disease. What about patients with recent acute coronary syndrome?
Dr Dominick Angiolillo: That's a great point. The reason why we conducted this study in a more stable setting was largely driven by two aspects. Well first of all, we wanted to have a run-in phase of patients switching from clopidogrel to ticagrelor to have some sort of baseline to reference to after the switch. And this would have been mostly ACS patients that would be less likely to be on clopidogrel. The second is purely a safety issue. We know that patients with acute coronary syndromes are associated with higher levels of platelet reactivity and in the context of a study where we do not know the pharmacodynamic profiles associated with de-escalation or better off we don't know the details.
And so, there was a safety consideration there which is why we did it in stable patients. But what we can say is tied with Gabriel's comment before in all the studies out there are not powered or do not have the rigor of a mega trial. Although we give our suggestions and recommendations, practical recommendations on how to switch, there is an increase in platelet reactivity and we stress in our manuscript that if you are going to switch, please try to delay this as much as possible because those increases in platelet reactivity for example, in a patient with an ACS for example, immediately after PCI, something that we probably would not want for our patients. I'm very happy actually that we conducted the study in the more stable cohort because we had less confounders. This is kind of the reason behind all this.
Dr Gabriel Steg: The last question maybe I would ask Dominick is whether he believe that results would be different if we had the patients on a maintenance therapy for longer with clopidogrel, do you believe that the risk of rebound or drug-drug interaction are the same early on after institution of therapy or later on? Is there any reason to expect a difference?
Dr Dominick Angiolillo: That's a great question. My personal opinion would be that with longer duration the platelet reactivity would have gone back down to baseline. We actually continue to study out up to around 10 days following the switch which we thought would have been sufficient time to get back to baseline and it was not the case particularly in the patients whose switch was a 75 milligram. The answer's probably yes. Probably yes. To redesign the trial again maybe having that 30-day time point as well would have been obviously of added value.
Dr Carolyn Lam: Thank you so much, Gabriel and Dominick. This has been extremely insightful. Fun as always.
You've been to Circulation on the Run. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
What do salty, Chinese meals, neurotransmitters, cancer, and pulmonary arterial hypertension have in common? Well, you are not going to want to miss this week's feature discussion. It's going to reveal a new therapeutic approach to pulmonary arterial hypertension that may just surprise you, coming up right after these summaries.
Do congenital heart defects signal a familial predisposition to cardiovascular disease? Well, this question was addressed in this week's first original paper from first and corresponding author, Dr. Auger, from University of Montreal Hospital Research Center in Quebec, Canada. Dr. Auger and colleagues aimed to determine whether the risk of cardiovascular disorders later in life was higher in women who had newborns with congenital heart defects. To answer the question, they studied a cohort of more than one million women who had delivered infants between 1989 and 2013 in Quebec. They showed for the first time that congenital heart defects in offspring were associated with increased risk of maternal cardiovascular morbidity later in life, including atherosclerotic disease, cardiac hospitalization, and cardiac transplantation. The association with subsequent cardiovascular morbidity risk was present for both critical and noncritical congenital heart defects. Thus, women who have given birth to offspring with congenital heart defects may benefit from early attention to traditional cardiovascular risk factors and more aggressive primary prevention strategies.
Acute myocardial infarction, or AMI, is a major cardiovascular complication of non-cardiac surgery, but what are the outcomes following perioperative AMI? This question was answered in the next paper from co-corresponding authors, Dr. Smilowitz and Berger, from New York University School of Medicine. The authors identified more than 8,000 patients who were diagnosed with AMI during hospitalization for major non-cardiac surgery using the 2014 US Nationwide Readmission Database. They found that perioperative AMI after non-cardiac surgery was associated with a high in-hospital mortality and a 19% risk of 30-day hospital readmission among survivors. The majority of hospitalizations after perioperative AMI were because of infectious, cardiovascular, or bleeding complications. Recurrent AMI occurred in 11% of patients re-hospitalized after perioperative AMI. At six months after perioperative AMI, more than 36% of patients were re-hospitalized, and the overall risk of in-hospital deaths was almost 18%. Thus, hospital readmissions and mortality among patients with perioperative AMI pose a significant burden to the healthcare system. Strategies to improve outcomes of surgical patients early after perioperative AMI are warranted.
What is the recent status of hypertension in China? Co-corresponding authors, Dr. Wang and Gao, from Fuwai Hospital, Peking Union Medical College, and Chinese Academy of Medical Sciences in China used a stratified, multistage, random sampling method to obtain a nationally representative sample of more than 450,000 residents from 31 provinces in mainland China from 2012 to 2015. The authors found that more than 23% of Chinese aged 18 years or old had hypertension, and that's equivalent to an estimated 284.5 million individuals. The prevalence of hypertension was similar in rural and urban settings, whereas three municipalities, mainly Beijing, Tianjin, and Shanghai had the highest prevalence of hypertension. Almost half the hypertensive population was aware of their hypertension. About 41% were treated, and only 15% achieved a blood pressure control. Among treated patients, barely 32% were prescribed two or more antihypertensive medications. Thus, this study revealed a considerable prevalence of hypertension in Chinese adults, as well as low awareness and control rates, representing an urgent public health message in China.
Patients with systemic sclerosis-associated pulmonary arterial hypertension have a far worse prognosis than those with idiopathic pulmonary arterial hypertension. But why is this the case? In the next paper, from co-corresponding authors, Dr. Hsu and Dr. Kass, from Johns Hopkins University School of Medicine, these authors tested whether the disparity involved underlying differences in myofilament function. They studied cardiac myocytes isolated from the right ventricular septal endomyocardial biopsies from patients with systemic sclerosis-associated pulmonary arterial hypertension, idiopathic pulmonary arterial hypertension, or systemic sclerosis with exertional dyspnea but without pulmonary arterial hypertension. They also looked at control right ventricular septal tissue obtained from non-diseased donor hearts.
They found that right ventricular myofilaments isolated from humans with systemic sclerosis-associated pulmonary arterial hypertension exhibited diminished contractile force and abnormal calcium sensitivity versus control myofilaments. This is in sharp contrast to the hypercontractile compensation in idiopathic pulmonary arterial hypertension. Systemic sclerosis patients with dyspnea and only exercise-induced pulmonary hypertension exhibited an intermediate right ventricular myocardial filament phenotype. These myofilament contractile abnormalities correlated strongly with in vivo right ventricular function at rest and right ventricular contractile reserve during exercise, suggesting a central role of right ventricular myofilament dysfunction in systemic sclerosis-associated pulmonary arterial hypertension.
In summary, these findings uncover key deficiencies in the right ventricles of systemic sclerosis-associated pulmonary arterial hypertension, and these findings suggest that therapies targeted at right ventricular myofilament contractile dysfunction may prove particularly useful for this vulnerable subpopulation. That wraps it up for our summaries. Now, for our feature discussion.
Today's feature paper promises a new therapeutic approach in pulmonary arterial hypertension. We know that pulmonary arterial hypertension is a rare disease, but nonetheless it casts a large shadow because it most commonly afflicts young women and remains a disabling disease. Despite treatment advanced in the last 20 years, high-risk patients still succumb at a rate of 15% annually. Moreover, our most effective therapy is a continuous infusion of parenteral prostacyclin, which is both cumbersome and expensive. Thus, there remains an urgent need for better therapies to improve survival and quality of life. Today's feature paper introduces a novel approach to this.
I'm so pleased to have the corresponding author, Dr. Sylvia Cohen-Kaminsky, from Inserm, Paris, France, as well as associate editor Dr. Charlie Lowenstein, from University of Rochester, to discuss today's special paper. You know, I'm gonna start with Charlie, because you have a way of explaining things and just putting the background to mechanistic papers so well. Could you do that for us, please?
Dr Charlie Lowenstein: Sure. When I started in research, I worked in a neuroscience laboratory. One of the things we studied was glutamate and its class of receptors. Glutamate, as you know, is one of the major neurotransmitters in the brain. The brain releases small amounts of glutamate, which acts as a messenger, neurons talking to other neurons. But when there's a stroke, the brain releases huge amounts of glutamate, and it's actually toxic and can cause damage, and mediate neuronal damage and cell death. Glutamate is a hot topic in the world of neuroscience. But in the cardiovascular field, people don't know much about glutamate. They don't appreciate glutamate as being important at all. So, I have a question for you, Sylvia. How did you start to get interested in glutamate and its family of receptors?
Dr Sylvia Cohen-Kaminsky: It started around 2000, and since 2000 we are having some clues about peripheral glutamate receptor in different cells in different organ. But basically, for vascular cells and for the topic of PAH, there was two things that make me thought about it. First of all, it was shown that the NMDA receptor contributes to the proliferation of different cancer cell types. Human tumor cells express the NMDA receptor, then an NMDA-receptor antagonist may inhibit cancer cell growth and migration. We know that pulmonary vascular cells from PAH patients have cancer-like properties. They are also proliferative and resistant to apoptosis, and they have several properties of cancer cells, such as metabolic shift and so on.
In addition, not only neurons in the brain express the NMDA receptor, but also brain microvascular endothelial cells that respond to an NMDA receptor activation by gross production, disruption of endothelial cell barrier, and monocyte transmigration. All these three processes are relevant to PAH development. That's why I thought that perhaps an NMDA receptor is expressed on microvascular cells from the lung, and perhaps we could have a process involving an NMDA receptor in this vascular remodeling.
Dr Charlie Lowenstein: As you know, there are three flavors of glutamate receptors. How did you discover that there was one particular kind, the NMDA receptor, that was really important for smooth muscle cells?
Dr Sylvia Cohen-Kaminsky: You are right. We did analysis of mRNA expression, and most of the known receptor in the brain, either metabotropic or ... ionotropic, sorry, indeed expressed in vascular cells and they may cooperate to activate this NMDA receptor exactly as it happens in the brain. We didn't work that on these other receptor, but we are pretty sure they are at work in cooperation with the NMDA receptor. Why though an NMDA receptor? Because it's an ion channel permeable to calcium, and the calcium is an event which can be important in cell proliferation. In addition, the first thing we have shown in these remodeled vessels when we did mass spectrometry imaging was increased level of glutamate and glutamine, its precursor. That was also an additional element that makes us think about this NMDA receptor.
Dr Charlie Lowenstein: I want to go from the receptor to glutamate. There are three or four amazing things about your paper. One of them is that you suggest that cells in the vascular are releasing glutamate, which is a neurotransmitter. Do you think those are the smooth muscle cells that are talking to other smooth muscle cells by releasing these messenger molecules?
Dr Sylvia Cohen-Kaminsky: Yes. Smooth muscle cells are talking to other smooth muscle cells. But we also did some work on endothelial cells, and they are also able to release this glutamate. So we think that vascular cells in the vascular wall are discussing together through glutamate, although we don't know yet the normal function of this NMDA receptor in the vascular system. However, in the pathology it's very clear that there is this release. What is very interesting is that this release can be triggered by pathways which are already down-regulated in PAH, such as the endothelin-1 pathway.
Dr Charlie Lowenstein: Another remarkable part of your observation is that the signaling with glutamate and glutamate receptors is hyperactivated in the setting of a major human disease, pulmonary artery hypertension. How did you figure out that glutamate is so important in this special disease?
Dr Sylvia Cohen-Kaminsky: Because we showed, as I already told you, this glutamate accumulation in the remodeled vessel. We used this mass spectrometry imaging which allows analysis of metabolites directly in the remodeled vessels from sections performed from extended lengths. We saw this glutamate accumulation together with glutamine accumulation, so the ligand was overexpressed. In addition, when doing western blots from these remodeled tissue dissected from ongoing arteries, we have shown that we have a particular phosphorylation of this receptor which is very well-known in the CNS. This phosphorylation is involved in sending the receptor to the membrane and stabilizing the receptor to the membrane. Having this phosphorylation means that NMDA receptor is engaged, activated in the remodeled vessels in situ.
Dr Charlie Lowenstein: In an experimental model, you explored the role of glutamate in two very nice, complementary ways. One is with a genetic approach, the NMDA receptor deficiency. The other is using drugs. What were the drugs, what were the pharmacology that you used to block glutamate's transmission, and how did that affect the mice?
Dr Sylvia Cohen-Kaminsky: We used drugs that are very well known in the CNS. We used two drugs. One is memantine, which is already commercialized for the treatment of Alzheimer's disease. The other one is MK-801, which has been produced initially as a potential pharmacological drug but it was too potent to be used in the CNS. Therefore, this drug is only used in research at the moment. But these two drugs were able to act on this vascular remodeling and a number of PAH parameters. We have explored at least 12 parameters involved in this animal model of PAH, and hemodynamic stable parameters of hemodynamics including intra-arterial pressure, vascular remodeling, right ventricular remodeling with different parameters that shows a certain index. The cardiomyocyte hypertrophy, the fibrosis, the inflammation inside the right heart and around remodeled vessels, all these parameters were modified by the drug.
In addition, in vivo we have shown the destruction of the NMDA receptor glutamate axis with decreased engagement of the NMDA receptor in pulmonary arteries by following this phosphorylation I mentioned, decrease of apoptosis resistance and also proliferation. This was shown also after the treatment with the drugs, and also decrease of endothelial cell dysfunction that could be followed in the blood through selecting those H.
Dr Charlie Lowenstein: Your results with this drug were really impressive. I love that part of your study. You showed when you block glutamate signaling, first of all, the blood vessels looked much better in a model of pulmonary artery hypertension. In an experimental model, blocking glutamate transmission really improved the way the vessels look. But secondly, what was really amazing was, normally in humans one of the big problems with pulmonary artery hypertension, as you said, is the right ventricle gets inflamed and fibrotic, and a lot of patients die from complications of right ventricular dysfunction. In your model, when you treat with MK-801, blocking glutamate receptor, the right ventricle looks a lot better. It was really an impressive part of your study.
Dr Sylvia Cohen-Kaminsky: I think that this is view on the effect of the vessels themselves, then the right heart can recover. But we may have a direct effect in the heart. If you remember this Chinese restaurant syndrome, when you eat too much Chinese food, which is full of glutamate, you have some cardiac involvement, arrhythmia, and so on. Initially, toxicologists thought that it passed through the central nervous system. But then they realized that maybe the NMDA receptor is expressed in cardiac cells, and indeed it is expressed and is colocalized with the ryanodine receptor, meaning that it could have a function in the heart as well. But this has, of course, to be explored precisely. We know from the transplantation that, when we transplant on with the lung, the heart can recover very well. We may have these two effects. One due to the relief on vascular remodeling, and the other perhaps a direct effect on the heart.
Dr Carolyn Lam: You know, I have to chime in now. That cuts too close to home with the Chinese food and glutamate. First and foremost, I just really have to say, Charlie and Sylvia, it's people like you who make basic science come alive and simply extraordinarily exciting. Taking glutamate, something that we've talked about in the context of Chinese food and neurotransmitters, and therefore showing the potential to even repurpose perhaps some drugs for pulmonary arterial hypertension. So let me just round up by asking you, what do you think our next steps, how far are these findings away from clinical application? Perhaps, Charlie, your thoughts?
Dr Charlie Lowenstein: While I think that the use of MK-801 to treat excess monosodium glutamate during a Chinese meal, maybe that's a little bit premature. I'm much more excited about the idea of using glutamate-receptor antagonists to treat or prevent or even reverse pulmonary artery hypertension, both its vascular and cardiac complications. I'd love to ask Sylvia, do you think these medications in this class, do you think NMDA-receptor antagonists are ready for clinical trials?
Dr Sylvia Cohen-Kaminsky: In fact, they are not ready as they are. We have a program in which we have designed hypothesized new NMDA-receptor antagonist that do not go to the brain, because we want that treating PAH has to be safe, and we don't want to interfere with brain system. So we created this new NMDA-receptor antagonist that do not go to the brain. At the moment, we are in the process of the documentation. We have two patents for two series of molecules, and we expect the drug conjugate by the end of this year. To reconjugate means that we have a number of properties on this drug, the pharmacokinetics, metabolism, selectivity profile, toxicity, and so on. We are doing all this physical chemical properties, and of course validation of these new molecules in the animal models as therapy alone and also as add-on therapy with existing therapies, such as these vasodilators. We hope that we can have an additive effect between an NMDA-receptor antagonist and current PAH drugs.
Dr Charlie Lowenstein: Sylvia, as you know, drug companies about 10 or 20 years ago invented all these amazing glutamate-receptor antagonists to treat central nervous disease like stroke. One of the amazing things about your discovery is you're suggesting that glutamate receptors in the periphery are great targets as well. The exciting thing about your observation is you're really opening up new therapeutic approaches for targeting neurotransmitters in the periphery. I think your discoveries are tremendously exciting and could open up new avenues in treatment of a disease, pulmonary artery hypertension, for which there really aren't effective therapies right now.
Dr Carolyn Lam: I couldn't have said it better. Thank you so much, Charlie. Thank you so much, Sylvia.
See, listeners? Aren't you glad you heard it here right on Circulation on the Run? Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation On The Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore. Our featured discussion today centers on the challenges of cardiovascular disease risk evaluation in people living with HIV infection, an important discussion coming right up after these summaries.
The first original paper this week provides experimental evidence that nicotinamide riboside could be a useful metabolic therapy for heart failure. First author Dr. Diguet, corresponding author Dr. Mericskay, from University Paris-Sud investigated the nicotinamide adenine dinucleotide or NAD homeostasis pathways in the failing heart. They found that an expression shift occurs in both murine and human failing hearts in which the nicotinamide riboside kinase two enzyme, which uses the nucleoside nicotinamide riboside was strongly up-regulated for NAD synthesis.
Nicotinamide riboside supplemented diet administered to murine models of dilated cardiomyopathy or pressure overloaded induced heart failure restored the myocardial NAD levels and preserved cardiac function. Nicotinamide riboside increased glycolysis as well as citrate and Acetyl-CoA's metabolism in these cardiomyocytes. Thus, nicotinamide riboside supplemented diet may be helpful in patients suffering from heart failure and may help them to cope with the limited myocardial ATP supply by restoring NAD coenzyme levels and its associated signaling.
In the single ventricle reconstruction trial, one year transplant-free survival was better for the Norwood procedure with the right ventricle to pulmonary artery shunt compared with the modified Blalock‒Taussig shunt in patients with hypoplastic left heart and related syndromes. In the paper in this week's journal, authors compare transplant-free survival and other outcomes between these groups at six years. First and corresponding author Dr. Newburger from Children's Hospital Boston and her group showed that the right ventricular pulmonary artery shunt group had similar transplant-free survival at six years, but required more catheter interventions before the Fontan procedure.
Right ventricular ejection fraction, New York Heart Association class and complications did not differ by shunt time. Cumulative incidences of morbidities by six years included 20% with a thrombotic event, 15% with a seizure, and 7.5% with a stroke. These data therefore emphasize the importance of continued follow-up of the cohort, and the need to find new strategies to improve the long-term outlook for those with single ventricle anomalies.
The next paper presents results of the CREATIVE trial, which stands for Clopidogrel Response Evaluation and Anti-Platelet Intervention in High Thrombotic Risk PCI Patients). First and corresponding author Dr. Tang from Fuwai Hospital National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College conducted a head-to-head comparison of the safety and effectiveness of intensified anti-platelet therapies either a double dose clopidogrel or adjunctive cilostazol and conventional strategy in 1078 post-PCI patients at high thrombotic risk as identified thromboelastography, which is a platelet function test.
The primary outcome was the incidence of major adverse cardiac and cerebral vascular events at 18 months post-PCI they find as a composite of all cause death, myocardial infarction, target vessel revascularization, or stroke. The authors found that the primary end point occurred in 14.4% of those in the conventional strategy. 10.6% in those given double dose clopidogrel alone. And 8.5% in those also given adjunctive cilostazol. Now, although both intensified anti-platelet strategies achieved increased platelet inhibition, only the triple strategy with adjunctive use of cilostazol significantly reduced adverse events in the long-term follow-up.
No increased rates of major bleeding was found with the intensified anti-platelet therapy regimes. Thus, in patients with low responsiveness to clopidogrel as measured by thromboelastography, the intensified anti-platelet strategies with adjunctive use of cilostazol significantly improved the clinical outcomes without increasing the risk of major bleeding.
The final original paper sheds light on the prevalence and predictors of cholesterol screening awareness and statin treatment among American adults with familial hypercholesterolemia or other forms of severe dyslipidemia. First and corresponding author Dr. Bucholz from Boston's Children's Hospital and their colleagues used data from the National Health and Nutritional Examination Survey, and showed a high prevalence of screening and awareness above 80%. However, there were relatively low rates of statin use among individuals with familial hypercholesterolemia at 52.3%.
And even lower rates among those with severe dyslipidemia at 37.6%. The discrepancy between the prevalence of cholesterol screening and treatment was most pronounced in younger patients, uninsured patients, and patients without a usual source of healthcare. This study highlights an imperative to improve the frequency of cholesterol screening and statin prescription rates to better identify and treat this high risk population. Additional studies are needed to better understand how to close these gaps in screening and treatment.
And that brings us to the end of our summaries. Now for our feature discussion. The natural history of infection with HIV has completely changed with the use of potent antiretroviral therapies. We now know that people living with HIV actually have morbidity and mortality patterns that really resemble the general population, especially with regards to cardiovascular disease, which is very prominent in this population. And I suppose it's this that has led to the assumption perhaps that risk prediction tools and intervention strategies that we apply in the general population may be used in patients living with HIV.
Is this the case however? Well, this week's feature discussion is going to be so enlightening. And it's so important we are talking across the world here, from South Africa to the United States, and of course with me here in Singapore. I am so pleased to have the authors of this week's feature paper and they are none other than Dr. Virginia Triant from Massachusetts General Hospital, Dr. Ralph D’Agostino from Boston University. And our associate editor, Dr. Bongani Mayosi from University of Cape Town. Thank you so much for joining me for today's exciting discussion. Virginia, could I ask you to first describe your study?
Dr Virginia Triant: As you mentioned in the introduction, we have found that patients infected with HIV have an increased risk of cardiovascular disease. That includes both myocardial infarction and stroke compared to age-matched controls in the general population. And extensive data has suggested that the etiology of this increased risk is related both to traditional cardiovascular risk factors, as well as novel risk factors that are specific to HIV infection. And these include chronic inflammation in the immune activation. So consequently, it remains relatively unknown whether established cardiovascular risk prediction functions are accurate for patients with HIV because they include only risk factors that are traditional factors and they don't reflect the complete mechanism that we know is at play in cardiovascular disease associated with HIV.
So in our study, we assess the performance of three established cardiovascular risk prediction functions, two Framingham functions, and then the ACC/AHA pooled cohort's equations and we applied this to a longitudinal HIV infected cohort that was comprised of men. And we investigated the performance of the risk scores in terms of comparing regression coefficients, discrimination and calibration, which are standard metrics in cardiovascular risk prediction. So I'll briefly summarize our overall results as a start. We found that overall, the risk prediction functions underestimated risk in our group of HIV-infected men.
We found that discrimination was modest to poor, and this was indicated by low c-statistics for all of the equations. And we also found that the calibration or the agreement between observed or predicted risk was also poor across the board for all three risk prediction functions. So our results suggests that simply taking the risk prediction functions and transporting them to an HIV infected group may actually result in mis-classification in terms of patient risk. And in underestimation of cardiovascular risk.
Dr Carolyn Lam: Well, Virginia, beautifully summarized of a beautiful paper. But perhaps at this point, we should take a step back and ask ourselves how exactly were these risk prediction scores originally developed. And I can't imagine asking a better person than Ralph. Ralph, could you take us on a jaunt along history and tell us how were those Framingham risk scores developed in the first place? Who are they supposed to be applied to? And did these results surprise you?
Dr Ralph D’Agostino: After the second World War, what was becoming quite clear is things like cardiovascular disease were becoming very prominent. Things like infections and what have you, we were developing all sorts of ways of handling them with medicines and so forth. But with cardiovascular disease, it's a thing that progresses slowly over the years and it starts wiping out people. And back in those days, one out of three men between the ages of 30 and 60 had some kind of cardiovascular event. Women weren't that bad off, but they were pretty bad off also. And so what happened is the American government and the American Heart Institute set up this study in Framingham, where they took a third of the individuals between the ages of 30 and 60 and actually followed them. They took values of variables like blood pressure, cholesterol, things they thought might be useful.
And took values on them. And they had to come back every two years and after as time went on, they took the data after six years, after 10 years they took the data, and started to look at how each individual's blood pressure related to cardiovascular disease. Does cholesterol, and the answer was yes. And then I started getting involved and we were developing these cardiovascular functions where you could actually take an individual, take their measurements now, and make a prediction that had a lot of validity, good discrimination, high predictability over what was going to happen in ten incidents and then the government, the US Government, started having guidelines and what we did is we ran a study where we took a number of different studies in the US, different cardiac studies, the ARIC studies, number of 'em, and we thought applying our functions how well would they do. And it turned out that for whites in the country, the Framingham functions did very well.
But Japanese-Americans in the country, it over-predicted. Then we found out that you could make a calibration adjustment and what we've gone to, like in China, we have a big study where we had a function and Framingham function it over-predicted but calibration adjustment would make enough corrections and so now with Jeanne and the HIV, our hope was that you could take these functions and see how they work on the HIV population. When we did it we were quite well aware, because people have been looking at different things, there's something beyond the original cardiovascular risk. And what the paper shows, quite nicely, these cardiovascular risks do have some relationship but they don't explain enough. The HIV population have a much bigger burden and a simple calibration adjustment just isn't going to work. We need new variables, we need new insights on what to add to these functions.
Dr Carolyn Lam: Thank you so much for that. That's just such important part of history because I have to thank you for those equations. We apply those definitely in our Asian cohorts with that calibration factor. But I was just reflecting as you were telling that story of how we've come full circle now to actually talk about an infection again. It's the midst of an infection, like HIV infection, that we're now testing these equations once again. What better than to ask than Bongani, you're in the epicenter, if I may, of HIV infection. What do you think of the applicability of these findings to the patients you see?
Dr Bongani Mayosi: Yes. These findings are clearly of great interest to us here in the Sub-Saharan African region because it is really the epicenter HIV pandemic. We found population, in terms of risk factors for arteriosclerosis disease still remains low although there clearly derives, for example, in the incidence of myocardial infarction that's being detected in a number of the leading centers now. And with HIV we have observed cases of myocardial infarction while they tend to be younger men who almost always smoke and who get a lot more of a thrombotic episodes.
When you catch them on a thrombotic load, you do not find arteriosclerosis disease. It's going to be important, I think, as we move forward to make sure that as we develop risk functions that will predict cardiovascular disease in patient HIV that the African epidemiological context is completed teaching that HIV affects younger people, affects large numbers of women, but that, quite clearly, is associated with decreased cardiovascular event and stroke and stroke is well demonstrated. But in terms of actually looking at the risk factor this population was still in the early day and certainly in future studies would have to have a major contribution of the African cohort.
Dr Carolyn Lam: That's true, Bongani, but may I ask how would you, perhaps, advise your African colleagues now to look at these data? Then I'd also like to turn that same question over to you, Virginia. What do we do? What's the clinical take home message of these findings?
Dr Bongani Mayosi: I think the message is true that HIV infection is associated with the increased risk of cardiovascular event, there's no doubt about that. That there are some risk factors that can carry through, such as the smoking population but it's important for all clinicians to be aware of that. The ordinary risk you find in using Framingham and other established risk functions is not going to give us all the information that we need. So that recommendation should come through we need to know that risk factors are unknown, that they're important and we need to learn more about these patients in order to give us a perfect prediction of what will happen in the future.
Dr Virginia Triant: I think the findings have a lot of clinical relevance. This suggests, I think, that there are a lot of clinical implications for any patient who has novel cardiovascular risk factors that may not be accounted for in heart functions. And what our findings suggest is that if functions don't reflect the actual composition of risk factors in the population, that can result in misclassification and thus we underestimate risk, we might miss high-risk individuals, high-risk patients who would benefit from aggressive risk reduction but are not currently receiving it. This is a real clinical challenge as sit in clinic and we pull up the scores and calculate them for our patients, whether that is a trustworthy number or whether we should, perhaps, thinking that it's higher, thinking that it's different than what we're seeing for predicted 10-year risk. I think what this suggests is that the functions may need to be further tailored to different populations and sub-populations to reflect the actual composition of risk factors in that population. Even within HIV patients and populations, the risk factors in South Africa might be different than those in Boston, with different relative contributions.
One of the next stepped planned for our team is to actually look at developing, new risk functions which are tailored to HIV and incorporating both HIV itself as a risk factor, as well as HIV specific variables and to attempt to see if we can improve the performance of these functions for HIV populations. Perhaps HIV or HIV related factors might become sort of a new cardiovascular risk equivalent and we can serve patients in this population as higher cardiovascular risk baseline. I also just wanted to mention, briefly, that I think that there are important clinical implications beyond HIV that extend to other chronic inflammatory conditions. Inflammation is increasingly recognized as important in cardiovascular risk and this way HIV can serve as a prototype population. But these results are likely to extend to a lot of different populations who have chronic inflammation for different reasons.
Dr Carolyn Lam: That's a great point, Virginia. As I'm listening, I'm wondering is there no end to this because now we say HIV and then we put other inflammatory diseases, then we say, "Well, women may be different from men," and then different ethnicities may be different. I think gonna be going closer and closer to precision risk prediction, if I might say. Could I just pick your brain here? What do you think the future is? Where's the room for machine learning approaches for risk prediction, individual almost down to that level? What do you think?
Dr Ralph D’Agostino: I think you're right on target. In some sense, the functions we have there's a sort of massiveness about it, when you come to view this population, back in the 50s and 60s and so forth, cardiovascular disease was such a major ... it still is a major problem ... such a major problem you identify some of the real items like the blood pressure and cholesterol, and you attack and develop functions on that and you'd find that you're affecting positively a huge number of individuals, but now as, like Jeanne was saying, and others have been saying, you start focusing, you've got this massive group of individuals who should have their blood pressure controlled and what have you, but if you go into HIV, you go into a number of other populations and so forth, there are other things that are driving these disease and driving the manifestations of the disease. It isn't that blood pressure isn't important, it's that there's other things that are important. And so it's machine learning and so forth and deep learning that you're gonna have to be dealing with manifestations on very high levels and maybe even get into genetics.
Look in the cancer field ... I do a lot of work with the FDA ... look at the cancer field now; how it's so genetically driven in terms of a lot of the drugs the so-called biomarkers, which are basically driven by uniqueness in populations. I think that's definitely going to be, or is the future of these cardiovascular functions.
Dr Carolyn Lam: Okay audience. You heard it, right here. These are exciting times. In the meantime, thank you so much for this precious, valuable piece of work. Virginia, Bongani, Ralph, it was great having you on the show.
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 is really a very important message, that hospitals have the capacity to influence a patient's adherence to secondary prevention and thereby potentially impacting long-term patient outcomes. Much more on this important paper coming right up.
Higher physical activity is known to be associated with lower heart failure risk. However, what is the impact of changes in physical activity on heart failure risk? The first paper in this week's journal, by first author Dr. Roberta Florido, corresponding author Dr. Ndumele from Johns Hopkins Hospital, provides us some answers. These authors evaluated more than 11,350 participants of the Atherosclerosis Risk in Communities, or ARIC, study who were followed for a median of 19 years during which there were 1,750 heart failure events.
They found that, while maintaining recommended activity levels was associated with the lowest heart failure risk, initiating and increasing physical activity even in late middle age were also linked to lower heart failure risk. Augmenting physical activity may, therefore, be an important component of strategies to prevent heart failure.
The next paper highlights the importance of bystander automated external defibrillator use. First author Dr. Pollack, corresponding author Dr. Weisfeldt from Johns Hopkins University School of Medicine sought to determine the association of bystander automated external defibrillator use with survival and functional outcomes in shockable observed public out-of-hospital cardiac arrests.
From 2011 to 2015, the Resuscitation Consortium prospectively collected detailed information on all cardiac arrests at 9 regional centers. The exposures were shock administration by a bystander applied automated external defibrillator in comparison with initial defibrillation by emergency medical services. The primary outcome measure was discharged with near or normal functional status as defined by a modified ranking score of two or less.
The authors found that among 49,555 out-of-hospital cardiac arrests, 8% were observed public out-of-hospital cardiac arrests, of which 61% were shockable. Overall bystanders shocked a remarkable 19% of shockable observed public out-of-hospital cardiac arrests. Bystander automated external defibrillation in shockable observed public out-of-hospital arrest was associated with an increased odds of survival with full or nearly full functional recovery compared to emergency medical services defibrillation.
The benefit of bystander automated external defibrillation use increased as the arrival of emergency medical service was delayed. Thus, efforts to increase the availability and use of automated external defibrillators in public locations are likely the most promising immediate ways to improve survival from out-of-hospital cardiac arrests.
The next paper suggests that the complement pathway may contain the secret to a successful cardiac regeneration. First author Dr. Natarajan, corresponding author Dr. Lee from Harvard University, and their colleagues performed a cross-species transcriptomic screen in 3 model organisms for cardiac regeneration, the axolotl, neonatal mice, and zebrafish, all of which underwent apical resection.
RNA-seq analysis showed that genes associated with inflammatory processes were found to be upregulated in a conserved manner. Complement receptors were found to be highly upregulated in all 3 species, particularly the induction of gene expression for complement 5a receptor 1. Inhibition of this particular complement receptor attenuated the cardiomyocyte proliferative response to heart injury in all 3 species.
Furthermore, following left ventricular apical resection, the cardiomyocyte proliferative response was abolished in mice with genetic deletion of complement 5a receptor 1. These data, therefore, identified the complement pathway activation as a common pathway for a successful cardiac regeneration.
The final study sheds light on the association between hyperoxia exposure after resuscitation from cardiac arrest and clinical outcomes. First author Dr. Roberts, corresponding author Dr. Trzeciak from Cooper University Hospital performed a prospective multicenter protocol directed cohort study that included 280 adult postcardiac arrest patients.
They found that early hyperoxia exposure, defined as a partial pressure of oxygen of above 300 millimeters mercury during the first 6 hours after return of spontaneous circulation, was an independent predictor of poor neurologic function at hospital discharge even after adjusting for a potential baseline and postcardiac arrest confounders.
That brings us to the end of our summaries. Now, for our featured discussion.
Medication nonadherence is a common problem worldwide and, indeed, the very topic of our featured discussion today. Our featured paper is so interesting because it tells us that hospitals may have the capacity to influence a patient's adherence to secondary preventive cardiac medications, thereby, potentially impacting long-term patient outcomes, and there are a lot of implications of that.
I'm so pleased to have with us the first and corresponding author, Dr. Robin Mathews, from Duke Clinical Research Institute, as well as the editorialist for this paper, Dr. Jeptha Curtis from Yale University School of Medicine, and our associate editor, Dr. Sandeep Das from UT Southwestern. Lots to talk about.
Robin, could you perhaps start by telling us what made you look at this issue of nonadherence and what did you find?
Dr Robin Mathews: The issue of medication adherence has been something that I think we've been dealing with in healthcare for some time now and, traditionally, we looked at factors that, on a patient level, you sort of also have an idea that maybe they might provider level factors that contribute to nonadherence, so we started thinking about this, what's the health system's role in adherence and is there a role? Do hospital and do providers have more of a role in promoting adherence than we acknowledged in the past?
We are fortunate to have a lot of great clinical data sources available, and the one that we used for this study is the ACTION-Get With The Guidelines Registry, and this is a quality improvement registry that's been around for some time. It's a great source of research and observational studies that has produced a lot of data over the years.
ACTION is a voluntary registry; there are several hundred hospitals that participate, and it gives us very good data, detailed data on the patient experience in the hospital for patients who come in with acute coronary syndrome, so we looked at patients who were enrolled in ACTION over the course of 3 years, from 2007 to about 2010, and looked at the typical patient level factors, medications that were given on admission, how they were treated and what medications they went home on.
What ACTION doesn't give us is longitudinal data, which is really what we were trying to get at here, so we were able to link this clinical data set using CMS data, which is administrative data, claims data, in order to ascertain longitudinal adherence, so we ended up, after exclusions of about 19,500 patients or so, and this spanned about 347 hospitals, of patients that we followed up to 2 years out, and our objectives of the study were 2-fold, one to assess adherence at 90 days for cardio vascular medication, secondary prevention medications that are typically used, so, in this case, we looked at beta blockers, ACE inhibitors, ARB, phenoperidine, and statins.
We looked at 90-day adherence, and then the question we had specifically was does adherence vary among hospitals? The second thing we wanted to knowledge was, if adherence does vary among hospitals, is there a relationship between hospital adherence and cardiovascular outcomes at 2 years, so we looked at MACE, which is MI, revascularization, readmission, stroke. We also looked at death and all-cause readmission, and also mortality.
What we found is that the adherence actually did markedly vary within the medication classes, but also among hospitals, and once we divided these groups into essentially high adherence hospitals, low adherence hospitals, and moderate adherence hospitals, there were these typical differences in terms of patient characteristics that one would expect in terms of comorbidity, socioeconomic status. Patients who were in the high adherence hospitals were more likely to be from ... to have a less comorbidity burden. They had higher income based on ZIP code, and they were more often represented from non-southern hospitals in the United States.
When we then correlated these two outcomes, what we found is pretty interesting. Patients who were in the low adherence hospitals were more likely to have the outcomes that I mentioned earlier. That's not too surprising, yeah, because I had mentioned that the patient mix in terms of the ... their case mix varied among these hospitals, so the logical question as well, maybe the hospitals that are ... have low adherence have low adherence because the patients are generally just sicker.
We know that there are certain high-risk groups and we know that the patients who are treated at some hospitals might be sicker than others, so we did our best to adjust to these, so we did a multivariable model. We adjusted for various patient differences, and we also looked at hospital-level differences, the best that we can ascertain based on the ACTION Registry. That was sort of where the interesting finding was the rates of major adverse cardiac events and death at readmission were mitigated somewhat closer to the null, but they remained significant.
Dr Carolyn Lam: What a detailed summary. Thanks so much.
Jeptha, I love your editorial that accompanied it. Could you put the study into context a bit for all of us? Why are these finding so impactful?
Dr Jeptha Curtis: It's rare that you get to review and editorialize a paper that has so many implications both from a clinical practice and policy standpoint, so I think they really hit on a understudied area, and really this paper should cause people to reflect on what's going on in their practice and at the institutions that they practice in.
I would say that adherence is just such a challenging problem that, as Robin articulated, has been refractory to change over 15 years. We've been studying this for a long time, and we know that the numbers had not improved over time.
What's different about this paper is that it really suggests a completely different approach to addressing nonadherence among patients, and if this is ... if their findings are true, if nonadherence is really actionable at the hospital level or attributable to the hospital level, it really opens up new avenues both for research as well as for quality measurements.
As I read this paper for the first time, I was really struck by thinking about how invisible adherence is to frontline clinicians. We just don't have the information to tell us are our patients taking their medications on a day-to-day basis, and we know that most of them are not because the research has consistently shown that a large proportion failed to take their medication, and Robin's paper showed that yet again, but I can't say that there's any steps that our hospitals are really doing to address that in a systematic fashion.
All of our efforts for quality improvement have really been towards making sure that patients are prescribed the medication on discharge, and in the setting of readmission and trying to prevent readmission to our hospitals, we are now having follow-up phone calls with patients to assess failures to taking medications and follow-up, but it's really ... That's it. There's really no systematic way that we're trying to ... if an individual patient or a group of patients are adherent to their medications, so this is really a whole new avenue.
What we don't know is how to improve it, right? I think that the first implication of this paper is that there are differences at the hospital level. Some hospitals seem to be doing this better than others. That could be driven by differences in case mix, but it could also be driven by differences in hospital practices, and I think this is a wonderful opportunity for future direction of research perhaps using positive deviance methodologies to go to those hospitals that have high adherence rates in really trying to understand what differentiates their practices from those of other hospitals.
Dr Carolyn Lam: Indeed, Sandeep, I remember some of the conversations we had as editors about this paper. We, too, were struck by the novelty, and you've mentioned before, Sandeep, that the novelty of perhaps nonadherence or adherence as a new performance measurement. Would you like to comment on that?
Dr Sandeep Das: Yeah, first thing, what was kind of interesting about the discussion surrounding this paper, there were some people who read it and just sort of read it as the message being nonadherence associated with worst outcomes, and I thought like that was pretty established, known, but then there were some people like Jeptha and Erica who really got it, who really understood what was novel and interesting about this, and I also congratulate Robin on a fantastic paper.
One thing I think that's really interesting, in my day job, I wear a couple of quality hats. I am the cardiology division quality officer, and health system quality officer for UT Southwestern, so I spend a lot of time thinking about quality, and I'll tell you there's quite a bit of metrics that he ... there's just a lot of things that now you feel they're not particularly substantive and they're very difficult to change, you have, you know, if aspirin on discharge, as Robin mentioned discharge adherence, aspirin on discharge is 99% and getting people to document the last 1% rather than fail to document it, there's not really a fulfilling challenge where you think, "I'm really impacting patient endpoints."
I was really struck by the opportunity here. We know that from studies like MI FREEE that adherence to medications even at a year is probably about a third of patients are not adherence, so it's really kind of interesting to take that as an opportunity. We should fixate on what are these therapeutic option or not therapeutic option can move the needle by a fraction of a percent, but these are medications that are proven to prevent MI and change lives, and there's a massive delta here that we can address. The concept that this is addressable on the hospital level is fascinating, and I'm a big fan of coming up with sort of systems level approaches to addressing problems.
Dr Carolyn Lam: Congratulations once again on this great paper. Just tell us what do you think of the next steps and what would your message be to those of us who practice outside of the US?
Dr Robin Mathews: Jeptha talked about where our focus should be in terms of what we can do on a hospital level. I think the ultimate answer is there's a lot of heterogeneity in terms of what is done, and I think that, expanding on his point about better investigating practices that currently exist, and whether that's surveying things, and we have a lot of great professional societies and registries that we can sort of reach out to these hospitals, find out what they're doing, what makes them different from the hospitals that are not doing those things and then really doing some rigorous testing to figure out if in fact these specific interventions that these hospitals have put in place are with the high likelihood leading to the effects that we've seen, so I think that surveying sort of what's out there, understanding what works in a rigorous way and then being able to systematically apply this or distribute this to other hospitals to share the knowledge and say, "Hey, this is what we think. We've actually done it."
Like Sandeep said, with the inpatient management of patients who come in with acute coronary syndrome, we've done it well. I think it sort of contributed. Our guidelines and adherence to these guidelines and the metrics that we've used have really demonstrated that we've sort of achieved high levels, but we sort of reached I think the ceiling for a lot of that, and you always have to be open to novel metrics and then the idea of focusing in on the transition from hospital to home and what we can do once they leave their door, once they leave the door of the hospital, I think would be useful.
In terms of the rest of the world, I mean, the US has very unique problems based on our payment models and access to care and whatnot, but I think a lot of the themes that we sort of have seen with medication nonadherence when it comes to patient-level factors and provider-level factors are sort of universal.
At the end of the day, patients need to be empowered, and they also need to have the tools to allow them to be successful in my opinion. I think we've for a long time in this space often said, "Well, this is sort of a patient that there's only so much that we can do as providers," but I think that papers like this highlight the possibility that there's probably more that we can do to make these impacts.
Dr Sandeep Das: One of the comments or a question that I had was the controversial thing is to what extent hospitals should be accountable for things that happen well after discharge? I think readmission is one that always comes up. There's factors that are outside our control, so one question is kind of to what extent should we be responsible for stuff that happens forward of 6, 9 months down the road?
The second question that I had or a comment that I had was I do think that there's going to be a generalizability to non-US settings because there's elements of this ... For example, this now would incentivize hospitals and discharging physicians to make sure that patient education is substantive, right? If the metric is, "Did you provide discharge instructions, yes or no?" then that's sort of trivially accomplished by handing them a piece of paper and checking a box, but, now, if we follow a metric like this, we're really going to be accountable for making sure people understand what they're supposed to be taking and have a path to get it and things like that, so it makes some of the transitions of care stuff, and that's a great point, some of the transitions of care stuff much more substantive.
Dr Robin Mathews: Sandeep's point is a very good point, and it's very difficult to come up with a clear answer for that and, like you said, the issue with readmissions and all sort of the factors that are involved from a social level and research level cloud that, so ... and, hence, I think something like readmission is controversial, and I think this sort of question will generate a lot of further questions about whether using medication adherence and holding hospitals responsible.
I will say that when we looked at adherence sort of in the short term at 90 days and we looked at it in the long term at a year, we saw there was sort of a drop off, but it wasn't as substantial it was earlier, so I think a lot of adherence in the short term after hospital discharge continues to decline over time, but it doesn't drop down as precipitously downstream as it does early on, and I think that, just like with readmission, there's been some data to suggest that near term readmission are more likely things that "could be preventable" as opposed to maybe a readmission toward the end of the month.
At the end of the day, it's a very difficult thing and there's a lot more discussion that needs to be had about this topic, but I think that with this, it gives me some hopefulness and I think everybody else on this call that at least we wouldn't then be able to prevent every adverse outcome that happens 2 years down the road, but we might be able to at least affect a substantial portion of them.
Dr Carolyn Lam: Listeners, you heard it. There's lots that we can do. This paper says a lot. Please do pick it up. Read the editorial as well.
Thank you so much for listening today, and don't forget to tune in again next week.
Dr Joseph Hill: My name is Joe Hill. I'm the Editor-in-Chief of Circulation and I'm very pleased today to be here today with Professor Daida from Juntendo University in Tokyo, Japan, as well as one of our associate editors, Professor Shinya Goto from Tokai University in Kanagawa, Japan. Dr. Daida is one of the senior authors on a very exciting clinical trial that we're publishing in Circulation. The first and largest trial comparing high-dose versus low-dose statins in Asia. Dr. Daida, would you please tell us more about the study?
Dr Hiroyuki Daida: Yes. Thank you. The trial, called REAL-CAD, is a randomized trial. We compare high-dose statins with low-dose statins in Japanese patients with stable coronary artery disease. The number of the patients is 13,000. It's the largest trial ever comparing high-dose and low-dose statins. We found that with that reduction of the primary end point, which is a composite end point, including cardiovascular death, non-fatal MI, non-fatal stroke, and unstable angina requiring hospitalization.
That is very exciting result because it is the largest trial ever and also the very first trial in Asia.
Professor Shinya Goto: Congratulations, Professor Daida, for that great achievement, in the REAL-CAD trial. Could you explain a little bit about the background and that the dose of statins in Japan is generally low, and what was the reason why we kept using low-dose statins, and is care to try change the standard of care in Japan and also East Asia? Could you give a comment on those two topics?
Dr Hiroyuki Daida: Our trial is quite similar to that of PNP trial of comparing Western extensive statin treatment and the Asia statin treatment. However, that extensive statin treatment, intensive statin treatment, is not popular in Asia, so we did that maximum clinical dose of statin, we use this dose in Japan. It is the maximum dose of statin approved in Japan.
Dr Joseph Hill: So as I understand it, the rationale was the thinking that Asians, East Asians, are unable to tolerate high-dose statin therapy. In this case you used pitavastatin. And, in fact, what you found was there were no increase in serious adversive events in high dose patients. And, just like Caucasians, they derived considerable benefit at multiple points in atherosclerotic cardiovascular disease metrics.
Dr Hiroyuki Daida: Actually, they didn't experience a really high-dose of statin in Japan so government approval is up to 4 mg of pitavastatin, a dose of that about 20.
Dr Joseph Hill: So, this is not what we would call high-intensity statin therapy but nonetheless, there was a dramatic benefit including an all-cause mortality, irrespective of the starting LDL level at the beginning of the trial?
Dr Hiroyuki Daida: That is right. We found that the effect is similar that the patient, the LDL is greater than 95 or less than 95. So, the effect is independent of the basal based on LDL level.
Professor Shinya Goto: The one thing, very exciting just like Joe mentioned, all cause of mortality, especially known cardiovascular caused mortality reduced with the use of high-intensive care of the statin. If any kind of speculation, what is the cause, reduce the inflammation or maybe reduce cancer, something like that. They have any kind of advance to an analysis?
Dr Hiroyuki Daida: We didn’t have further analysis but we are not so keen to emphasis the total mortality because maybe that is a chance of the effect but this is the largest trial, so the result is really exciting in this kind of aspect.
Dr Joseph Hill: So, I would reiterate Shinya’s congratulations. This is a monumental piece of work. The largest clinical trial comparing high dose versus low dose statin. The largest ever. The first in Asia. You found a benefit that makes total sense across what we know from other trials and this will change practice. Your work, I believe, will change the way patients with atherosclerotic cardiovascular disease is handled in Japan.
Dr Hiroyuki Daida: Yes, actually the current guideline in Japan for the secondary condition. The condition is LDL less than 100 and for the really high-risk secondary condition listed seventh. We didn't recommend high-dose statin initially, so, this trial result is kind of like this, changing.
Dr Joseph Hill: I can't resist asking, what comes next? What's your next project?
Dr Hiroyuki Daida: Maybe we need to have a further reduction of LDL. We have another drug, other potent drug recently. We need to investigate all of the new drug such as PCSK9 inhibitor in secondary prevention.
Professor Shinya Goto: That's wonderful. Do you have any time to extend observation of the trial? I think the trial is relatively still superior as compared to the global long-standing trial. Really, that's fine, that effect of statin on the cholesterol and even it's different from Japan and other regions of the world. There ought to be intriguing thing, I would like to know, what are you waiting to extend that observation now?
Dr Hiroyuki Daida: Fortunately, we do not intend to extend the follow-up. The whole thing is about four years but we do not plan to extend. We will further analyze the data for some group and our kind of CRP and effect of the baseline.
Dr Joseph Hill: Lots of secondary analysis underway, undoubtedly. Let me thank both of you for being here, Professor Daida and Professor Goto, I congratulate you again. It's not often that you make a practice-changing intervention in modern-day medicine. I salute you and we are honored and thrilled to publish your outstanding work in Circulation. Thank you both.
Dr Hiroyuki Daida: Thank you very much.
Professor Shinya Goto: Thank you very much.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, associate editor from the National Heart Center of Singapore and Duke National University of Singapore. Our featured discussion today is a wake-up call because despite substantial efforts to promote cardiac rehabilitation in guidelines and performance measures only a small percentage of patients are receiving this and there is a remarkable regional variation. Lots of lessons to be learned here coming right up after these summaries.
More children with congenital heart disease are surviving into adulthood, and congenital heart disease is associated with risk factors for dementia. But what is the actual risk of dementia in congenital heart disease adults? Well, in this first paper from first and corresponding author Dr. Bagge from Aarhus University Hospital in Denmark, the authors used medical registries and a medical record review of all Danish hospitals to identify more than 10,600 adults with congenital heart disease diagnosed between 1963 and 2012 and followed up until the hospital diagnosis of dementia or death, emigration, or the end of the study in the end of December 2012.
For each individual with congenital heart disease the authors identified 10 members of the Danish general population matched on sex and birth year. They found that the risk of all-cause dementia was increased by about 60% in congenital heart disease adults compared with the matched general population. The risk was higher for early onset dementia, that is dementia at less than 65 years of age, in which the risk was more than double. The risk was also elevated for all levels of congenital heart disease complexity, including those with cyanotic potential. The relative risk remained increased for those without extra cardiac defect or acquired cardiovascular diseases.
These results really underscore the importance of understanding the risk of adverse long-term neurologic outcomes in the growing and aging population with congenital heart diseases.
The next paper suggests that patient outcomes after lower limb revascularization have improved in England over recent times. This paper from first and corresponding author Dr. Heikkila from London School of Hygiene and Tropical Medicine used individual patient records from hospital episode statistics to identify almost 104,000 patients who underwent endovascular or surgical lower limb revascularization for infrainguinal peripheral artery disease in England between 2006 and 2015. During this 10-year period the estimated one-year risks of major amputation and death reduced after both endovascular and surgical lower limb revascularization in England. These trends were observed for all categories of peripheral artery disease severity, with the largest reductions seen among patients with the most severe underlying disease.
These encouraging trends coincided with a period of centralization and specialization of vascular services in England, although the current findings cannot be interpreted as resulting directly from this reconfiguration of services.
The next paper presents experimental data showing that targeting the Janus kinase and signal transducer and activator of transcription or JAK-STAT pathway may represent a disease-modifying strategy in inflammatory vasculopathy. First author Dr. Zhang, corresponding author Dr. Weyand from Stanford University School of Medicine examined whether persistent vessel wall inflammation in giant-cell arthritis is maintained by lesional T cells and whether such T cells are sensitive to the cytokine signaling inhibitor tofacitinib, which is a JAK inhibitor that targets JAK3 and JAK1.
To do this, vascular inflammation was induced in human arteries and grafted into immunodeficient mice that were reconstituted with T cells and monocytes from patients with giant-cell arthritis. Mice carrying inflamed human arteries were then treated with tofacitinib or vehicle. They found that tofacitinib suppressed T cell invasion into the artery, inhibited proliferation and cytokine production of vasculitogenic T cells and curbed survival of artery resident T cells. Tofacitinib treatment prevented neoangiogenesis and intimal hyperplasia in these inflamed arteries. Thus, inhibition of JAK-STAT signaling with tofacitinib effectively targeted multiple disease-relevant processes in inflammatory vasculopathy and thus represents a potential disease-modifying agent.
The next paper provides important insights into how coronary artery calcification burden and cardiorespiratory fitness, which are actually two independent predictors of cardiovascular disease but may interact with each other to impact cardiovascular risk. First author Dr. Radford, corresponding author Dr. Levine from the Institute of Exercise and Environmental Medicine Texas Health Presbyterian Hospital and UT Southwestern Medical Center studied 8,425 men without clinical cardiovascular disease who underwent preventive medical examinations that included an objective measurement of coronary artery calcification and cardiorespiratory fitness between 1998 and 2007.
They found that cardiovascular disease events increased with increasing coronary artery calcification and decreased with increasing cardiorespiratory fitness. Adjusting for coronary artery calcification levels for each additional MET of fitness there was an 11% lower risk of cardiovascular disease events. When both coronary artery calcification and cardiorespiratory fitness were considered together there was a strong association between continuous cardiorespiratory fitness and cardiovascular disease incident rates in all coronary artery calcium groups. Thus, the take-home message is for any baseline age and level of coronary artery calcification greater fitness is associated in a continuous fashion with lower risks of cardiovascular disease events.
And that wraps up our summaries. Now for our feature discussion.
We all know how cardiac rehabilitation is. It's strongly advocated in guidelines, it's very well highlighted in performance measures. But how well are we actually doing? Well, today's feature paper really gives us some very valuable information and really kind of holds a mirror in our face, doesn't it? I'm so pleased to have with us the first and corresponding author of the paper Dr. Alexis Beatty from VA Puget Sound Health Care System and University of Washington as well as Jarett Berry, our associate editor from UT Southwestern. Alexis, could you tell us what did you see when you looked at cardiac rehabilitation among the Medicare and VA populations?
Dr Alexis Beatty: Overall participation in cardiac rehab after an MI or a PCI or a bypass surgery is pretty low, only about 16% of people in Medicare and about 10% of people on the VA actually participate in cardiac rehab. But the interesting thing is that we saw pretty wide variations from state to state in participation. So some states had pretty high participation, upwards of 40% of patients, and some states had only 1, 2, 3% of people participating.
Dr Carolyn Lam: Were there any patterns to this, any factors that you teased apart?
Dr Alexis Beatty: We did observe that some regions of the country appeared to be doing better than others. So for instance, the West North Central region of the United States, Nebraska, South Dakota area has high participation in both populations and other regions like the Pacific, California, Oregon, Washington, Hawaii, Alaska, have lower participation in both populations.
Dr Carolyn Lam: And any postulations on why this may be the case?
Dr Alexis Beatty: Yeah, I have some theories. We did try to look at whether it was due to patient characteristics, hospital characteristics, socioeconomic status, and it doesn't really seem to be any of those things that are driving the differences, which leads me to believe that it's actual practice variations. So I think that literally the systems are set up better in some areas of the country than others to get patients into cardiac rehab.
Dr Carolyn Lam: And as you beautifully wrote in your paper, that means that there may be an opportunity here to identify best practices here, isn't it? Jarett, you've been thinking about this a lot. What do you think?
Dr Jarett Berry: Yeah, I was curious, Alexis, it is interesting that the hospital variation that you saw, the on-site cardiac rehab was fairly consistent across cardiac rehab participation rates in Medicare but there was quite a bit of variability in the access to an on-site cardiac rehab site in the VA patients. I thought that was an interesting observation because it does suggest perhaps that what's driving regional variability looks to be fairly complex as you point out in your paper. But I just wanted to have you speculate a little bit or think a little bit about strategies for how we might think about improving cardiac rehab participation given the fact that there doesn't seem to be one particular answer to this problem. And so as you think about this longstanding challenge, how would you think about the future, about how we could actually really move the needle in increasing cardiac rehab participation?
Dr Alexis Beatty: There's a lot of different ways that I think that we can work to start moving the needle. And as you point out, not every VA location has a cardiac rehab center on-site and sites that do have cardiac rehab on-site do tend to do better at getting their patients into cardiac rehab. And I think it may just be that there are people there who are interested in cardiac rehab and are promoting it to patients. And then there probably are some access issues as well. But I think it's not just kind of an "if you build it they will come" sort of proposition. Having cardiac rehab centers is important but then having systems in place to get people into cardiac rehab and get people going to cardiac rehab are just as important.
And so I've talked to a lot of the VAs that have centers, don't have centers, do a good job of getting people in, don't do a good job of getting people in. And even in these places that don't have cardiac rehab on-site, if they have a system in place that helps get patients into cardiac rehab they're still able to achieve pretty high rates. And so a lot of that is just doing kind of setting it up as an automatic order and having a nurse or exercise physiologist or somebody be a navigator for the patients through the process.
And then the other thing I really want to stress is the importance of providers recommending it to patients. I think that's the strength with which the providers sell cardiac rehab can really make a big difference.
Dr Jarett Berry: It's interesting, I just took over cardiac rehab as a medical director here at Southwestern about a year and a half ago and I've been struggling with this. And one of the interesting things that I just would love to get your thoughts on that I noted, which doesn't seem to get a lot of attention in the literature to me, is the role of co-payments. I don't know if most physicians who aren't involved in this space appreciate that for most insurance and for Medicare, it may not be the case for VA, I can't speak to that, but the co-payment amount for each time you come, for each visit is between $30 and $50 per visit. That seems to me in some ways ... I know you didn't address it at all in your paper, but just keeping this conversational ... What do you think the role of some of these other less discussed factors are such as just co-payment amounts that might actually be having a bigger effect on participation? Because I know if I had to pay a 1,000 bucks to go to cardiac rehab I might think twice about it.
Dr Alexis Beatty: Yeah, and I think the co-payment issue is a very real issue too and there's a lot of policy level things that makes cardiac rehab difficult. So one is this co-pay issue, there also then other changes to the way it's administered like where the location of the cardiac rehab can be and how hospitals get reimbursed for that. It has to be prescribed by a physician, it can't be prescribed by a nurse practitioner or a PA, it has to be supervised by a physician. There's a lot of restrictions on cardiac rehab that can just, practically speaking, make it difficult to deliver both from the patient and the provider and health system level.
And what I tell my patients when I am trying to get them to go to cardiac rehab, and we do have co-payers in the VA too that are kind of on a sliding scale depending on patients’ means. And so I tell them that it's an investment. You are making this upfront investment of your time and money and effort to get yourself healthy and learn how to be healthy in the long term. So we know that people who attend cardiac rehab are less likely to be hospitalized and are less likely to die from their heart disease, and so it's an important investment to make and that's sometimes the hard message to sell and I wish it were easier to sell.
Dr Jarett Berry: I totally agree with you. My own patients and also the patients that I helped manage through cardiac rehab have received such benefit in many different areas from the participation. But yeah, it is an investment.
I wanted to ask another question, if I may Carolyn, about the future. And you alluded to this in your paper, I know your work with Mary Whooley, you guys have done great work thinking about rolling out home-based cardiac rehab. And I think personally that the future of cardiac rehab for most patients, that we're really going to move the needle—I mean some of the policy issues are really important—but can you comment on just telling us what home-based cardiac rehab is and to what extent you think that is a potential solution to deal with these persistently low participation rates?
Dr Carolyn Lam: Actually Jarett, if I may just butt in before Alexis answers, I was about to ask that because I was just placing myself in the patient's point of view. And I mean even me, I hate going to gyms now and much rather work with a home app instructing me what to do and I can just do it here, you know what I mean? So I think that's a great question. Alexis?
Dr Alexis Beatty: I agree, the future is home cardiac rehab and using all the tools that we have at our disposal to make it easy to deliver home cardiac rehab. The evidence isn't quite as strong for home cardiac rehab but the existing evidence does suggest that it's equally effective to center-based cardiac rehab, it's just not reimbursed in the United States. So functionally it only exists in sort of integrated health systems like the VA.
The VA, for instance, has started delivering home-based cardiac rehab programs. I think it's now at over 30 centers in the US. And this has basically started in the last five years. And the programs are pretty similar to a center-based cardiac rehab program in that patients come in and they get an in-depth assessment from cardiac rehab professionals. But then the difference is that they go and exercise on their own at home and they check in with the cardiac rehab professionals usually on a weekly basis over the telephone. And so it ends up being more of like a coaching relationship between the cardiac rehab professionals and the patients who are exercising on their own at home. And a lot of patients really like it because, as you pointed out, it's much more convenient for them, they don't like going to a gym, they'd rather be walking around in their neighborhood or going to their local community pool to swim. So it just sort of addressed a lot of these patient issues and they don't have to pay a co-payment. So it can take some of these other barriers that are there.
Dr Jarett Berry: Like a Peloton bike for cardiac rehab, right?
Dr Alexis Beatty: Yeah. I mean you could even do that. For instance, in HF-ACTION they actually gave people exercise equipment for a HF-ACTION study for the home segment of the HF-ACTION study. So there certainly are models whereby we could just be giving exercise equipment. And in the VA I can mail people these little exercise paddlers that they can put on their floor or their table and you can use them with your legs or your arms. So certainly being able to send some of this exercise equipment to your patients may help them get them into doing things. But I think home cardiac rehab is the future.
And then also I do work on using technology to help deliver home cardiac rehab and I view technology for this space not as the solution but as a tool to help you deliver home cardiac rehab. And now that technology is so ubiquitous, I think that we need to now learn how to use the technology to help us better deliver cardiac rehab in a way that meets the patients' needs.
Dr Carolyn Lam: Wow. Jarett, I've actually got a question for you. You were just saying that you run the rehab unit there, so what messages did you take home from this paper?
Dr Jarett Berry: What I took home from this was exactly what we've been discussing, this issue of low uptake of cardiac rehab even in the scenario where you have a model where you're delivering this through Medicare or the VA we still see very low participation, albeit there is some variability. And so my interpretation after doing cardiac rehab here at Southwestern for the last year and half is exactly what Alexis is saying, is that we need to be really thinking more creatively about how we can deliver cardiac rehab where the patients are and not requiring them to participate in centers of cardiac rehab that are maybe 30, 40 miles from their home and in the middle of the workday, all of which just really makes such a model inefficient.
So I just think what this paper does really solidify is that we really need to be thinking broadly and creatively about how to bring cardiac rehab to more patients because the way we're doing this now I think unfortunately is just ineffective.
Dr Carolyn Lam: Anything to add, Alexis? This is great.
Dr Alexis Beatty: So one other point that I would like to mention. I think about 10 years ago there was another paper that used a very similar method, and we based a lot of our methods off of that paper by Suaya about 10 years ago. And they found that the rate of participation in cardiac rehab was somewhere very close to ours, I think it was 18% and we observed 16%. And since that paper was published cardiac rehab got included in guidelines, included as a performance measure, and there has been a big push and a lot of attention to try to get people into cardiac rehab and we have moved the needle zero since that time. So I think clearly something new is needed to move the needle for cardiac rehab just as Jarett was pointing out. So we got to do something because what we're doing isn't working.
Dr Carolyn Lam: That's a great call and thank you for showing that to us so clearly in your paper.
Dr Jarett Berry: Yeah, thanks Alexis and thanks for being so responsive in the revision process, it was a real pleasure to work with you all on this really important paper.
Dr Alexis Beatty: Thank you so much for publishing this paper. I feel I've been working on this for like five years.
Dr Carolyn Lam: Well you heard it here, listeners. Thank you for joining us today. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to "Circulation On The Run," your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, Associate Editor, from the National Heart Center, and Duke National University of Singapore. Our featured paper today is so important for cardiac surgeons and their patients. It answers a question of whether targeting a higher versus a lower blood pressure during cardiopulmonary bypass helps to prevent cerebral injury. Curious? Well, more soon right after these summaries.
In the first original paper this week, MicroRNA-22 is shown to be a novel mediator of vascular smooth muscle cell, phenotypic modulation, and neointima formation. Co-first authors, Drs. Yang and Chen, co-corresponding authors, Dr. Zhang from Zhejiang University and Dr. Xiao from Queen Mary University of London and their colleagues used wire injury mouse models to show that MicroRNA-22 controls vascular smooth muscle cell phenotype and injury-induced arterial remodeling by modulating multiple target genes, including methyl-CpG-binding protein 2, histone deacetylase 4, and ecotropic virus integration site 1 protein homolog.
The authors observed that MicroRNA-22 expression was suppressed in human femoral arteries with atherosclerotic plaques, and that there was an inverse relationship between MicroRNA-22 and its target genes in healthy and diseased arteries. Furthermore, local delivery of MicroRNA-2 in the injured arteries prevented adverse arterial remodeling, thus suggesting that site-specific delivery of MicroRNA-22 mimics may be a potential therapy for in-stent restenosis.
The next paper adds to our understanding of the pathobiology of pulmonary hypertension related to left-sided heart failure and importantly adds histomorphometric evidence from human lung specimens at autopsy or surgery.
First author Dr. Fayyaz, corresponding author Dr. Redfield, and colleagues from the Mayo Clinic studied patients with heart failure with preserved or reduced ejection fraction and pulmonary hypertension and compared these to normal controls, as well as patients with primary pulmonary veno-occlusive disease.
They found that patients with heart failure and pulmonary hypertension had global pulmonary vascular remodeling with thickening of the media and intima in arteries and thickening of the intima in veins and small pulmonary vessels compared to normal control subjects.
This venous and small-vessel intimal thickening was more severe than the arterial intimal thickening in heart failure with a pattern that was similar to patients with pulmonary veno-occlusive disease. In fact, the severity of pulmonary hypertension correlated most strongly with venous and small vessel remodeling rather than arterial remodeling.
These findings expand our understanding of the pathobiology of pulmonary hypertension in heart failure. It also suggests that pulmonary venous remodeling in heart failure may predispose to worsening alveolar edema with pulmonary vasodilators as in primary pulmonary veno-occlusive diseases.
Are there sex and race differences in the lifetime risk of HFpEF versus HFrEF? First author Dr. Pandey, corresponding author Dr. Berry from UT Southwestern Medical Center, and their colleagues used participant level data from two large respective cohort studies, the Cardiovascular Health Study, and the Multi-Ethnic Study of Atherosclerosis to determine remaining lifetime risk estimates for heart failure with preserved and reduced ejection fraction at different index ages.
They found that compared to women, men have a higher lifetime risk of HFrEF, heart failure reduced ejection fraction with a similar lifetime risk of HFpEF, or heart failure preserved ejection fraction. Compared with blacks, non-blacks have a similar lifetime risk of developing HFrEF but a higher risk of HFpEF.
Lifetime risks of HFpEF and HFrEF were similar and substantially higher in those with versus without antecedent myocardial infarction.
In summary, these findings provide novel insights on sex and race differences in the lifetime risks of HFpEF and HFrEF, and may help health policymakers in appropriate resource allocation for targeting HFpEF and HFrEF specific preventive therapies at the at-risk population.
What are evidence-based blood pressure targets during pediatric cardiopulmonary resuscitation? Well, first and corresponding author Dr. Berg from Children's Hospital of Philadelphia and his colleagues studied a multi-center population of children with invasive arterial blood pressure monitoring during in-hospital ICU cardiac arrest, and the Collaborative Pediatric Critical Care Research Network Intensive Care Units, between 2013 and 2016.
They found that a mean diastolic blood pressure greater or equal to 25 millimeters of mercury during cardiopulmonary resuscitation in infants, and greater or equal to 30 millimeters of mercury in children 1 year old or greater, was associated with a 70% greater likelihood of survival to hospital discharge, and a 60% higher likelihood of survival with a favorable neurologic outcome.
On the other hand, survival rates were markedly lower with mean diastolic pressures less than 20 in infants and less than 25 in children 1 year or older. Thus, clinicians should consider targeting diastolic blood pressure of 25 or greater in infants, and 30 or greater in children 1 year old or older during cardiopulmonary resuscitation when invasive arterial blood pressure is monitored.
That wraps up our summaries for this week. Now for our featured discussion.
Does a higher versus a lower blood pressure target during cardiopulmonary bypass surgery reduce the risk of cerebral injury? Well, the feature paper today provides some answers, and we have the first and corresponding author, Dr. Anne Vedel from University of Copenhagen with us today, as well as our associate editor, Dr. Timothy Gardner, who's a cardiac surgeon from University of Pennsylvania.
Thank you so much for being with us today and this was a terrific trial, a very difficult trial to carry out. Could you please tell us a bit more about it?
Dr Anne Vedel: Cerebral injury is an important complication after cardiac surgery with the use of cardiopulmonary bypass. Up to half of our patients suffer these perioperative silent strokes. Therefore, in Copenhagen we conducted a trial investigating the importance of two distinct blood pressure levels during cardiopulmonary bypass. Now, on this subject of optimal perfusion strategy during bypass, there are many opinions, but also a stunning lack of convincing evidence, for instance, when it comes to blood pressure management.
Now, the question is whether normal physiological principles, such as cerebral autoregulation therapy, whether they apply during bypass, or if perfusion pressure indeed does play a less important role when blood flow is mechanically provided in an uncomplicated and sufficient way by the heart and lung machine.
So, in a patient on the assessor-blinded randomized trial, we allocated patients to a higher or a lower MAP target, 70 to 80, or 40 to 50 millimeters of mercury, respectively, by titrating intravenous norepinephrine during bypass.
Pump flow levels were set at 2.4 liters per minute per square meter of body surface, and our primary outcome was the total volume of new ischemic cerebral lesions, expressed as a baseline MRI, and opposed to the difference between the baseline MRI and the postop MRI on day three to six. Secondary outcomes were a number of new ischemic lesions and newer psychological test evaluations.
Now among the 197 patients enrolled who were scheduled for coronary artery bypass, or heart valve repair surgery, or a combination of both, we found that 53% of patients in the low target group as opposed to 56 in the high target group had new cerebral lesions on their postop cerebral MRI.
The primary outcome of volume of new cerebral lesions was comparable between groups, and so was the total number of newer lesions. No significant difference was observed in stroke rates in frequencies of postoperative cognitive dysfunction, or in severe adverse event rate.
Therefore, we concluded that among patients undergoing on-pump cardiac surgery, targeting higher versus a lower mean arterial pressure did not seem to affect the volume or number of new infarcts.
Dr Carolyn Lam: Wow, thank you so much, Anne. Tim, you think about these issues a lot more than I do as a non-surgeon. Could you tell me what your insights were?
Dr Tim Gardner: You know, it's a very difficult study to do a randomized control trial in this environment, and they're really to be congratulated for doing it. As Anne acknowledges, this is not an area where randomized trials are very frequent.
The first thing about the trial, I think, is a growing awareness among all of us that there seems to be a lot of imaging evidence of what we call injury or changes based on diffusion-weighted imaging in patients after cardiopulmonary bypass. This is not the first study that shows that.
But the question is are these incidental, trivial lesions? I'd have to, again, ask Anne to clarify how many of the patients in either group, what percentage had what we would consider evidence of overt strokes?
Dr Anne Vedel: Well, overt strokes, as opposed to silent strokes, 1 patient in the lower target group had stroke and 6 patients in the high target group, which corresponds to 1 as opposed to 7%.
Dr Tim Gardner: That was not quite statistically significant difference but headed in that direction with the assumption that if you have a larger sample size there might be, in fact, some association with overt stroke using the high target vasopressor approach, is that right?
Dr Anne Vedel: We can only speculate. But as you do, yes, I agree.
Dr Tim Gardner: To go back to the original question, the significance of these, well, you were referring to as silent strokes. Can you comment on the clinical significance there? We hear of silent heart attack. What is a silent stroke and what are the implications of that long term for patients?
Dr Anne Vedel: In other fields of research on the silent strokes, it's been shown that they correlate to both frequency of postoperative cognitive dysfunction and also later development of mild cognitive impairment and dementia. But these kinds of results, there isn't enough research in the field of cardiac study for us to say the same. But those are the implications from other research fields.
Dr Tim Gardner: But you can understand from the perspective of a cardiac surgeon, and this concern has been expressed and talked about in the literature for 20 years or more, the possibility that even what seems to be, with no injury apparent and no overt stroke, there may be some neurological consequence to cardiopulmonary bypass.
So just to move on from that because I agree that we just don't have any reliable information that these silent strokes result in late or permanent injury, I think again the finding that manipulating the blood pressure, which seems to be intuitively beneficial in patients, especially elder patients, did not, in fact, show any benefit and, in fact, may have been associated with a slight increase in overt stroke. Is that a fair conclusion from your study? A summary of your study?
Dr Anne Vedel: I would say it is a fair conclusion, and surprisingly so. The question is whether it is the blood pressure or the means that we apply to have this increase in blood pressure that is the point of interest here.
Dr Tim Gardner: You mean whether, in fact, using the norepinephrine, the vasoconstrictor, to increase the blood pressure whether that itself, it certainly didn't benefit, it may have been a problem.
Dr Anne Vedel: Exactly. That's what I speculate might be the case. But I also think it's fair to say at this point that this is somewhat artificial physiological scenario, the cardiopulmonary bypass.
Dr Tim Gardner: I agree with that, that you're controlling blood flow and the patient is exposed to a lower hemoglobin and oxygen-carrying capacity and so on. But I think what struck me about your findings, or strikes me about your findings, is what appears to be in many of the patients, the low target patients, pretty effective autoregulation of the cerebral circulation, despite the artificiality of cardiopulmonary bypass.
I think that's, again, something that has been not well known or well accepted by many people, thinking that if you lower body temperature, you lower hemoglobin, autoregulation may not be enough to maintain good cerebral perfusion. It looks like this study shows that in these patients, autoregulation worked fine. Is that fair?
Dr Anne Vedel: Yes. Or sufficient blood flow was delivered. All in all, what's new in our study, I think, is that hypertension per se shouldn't necessarily be considered a proxy for hyperperfusion during bypass.
Dr Tim Gardner: Yeah, that's a very good qualification. So none of your patients, despite being in their mid to late 60s had evidence of carotid artery disease or whatever? Those patients were excluded from the trial, is that right?
Dr Anne Vedel: No, that's not correct. We didn't screen for carotid artery disease because we don't routinely do that in our institution. As we describe in our discussion, we included quite a heterogeneous study sample by enrolling the patients that came to us. We didn't screen and we didn't exclude these patients that you mention.
Dr Tim Gardner: Do you know how does your group handle a patient that is known to have carotid artery disease, comes in with a known either prior endarterectomy or established disease? Do those patients, are they treated any differently either as a result of the study or just in general?
Because that is a targeted group of patients, at least in my own experience, that we would be more concerned about allowing autoregulation to be the determinant, feeling that if there is a fixed stenosis in the carotid artery that we might need to increase the mean arterial pressure.
Dr Anne Vedel: I can certainly understand your point and, of course, it is a concern in our center, as well. But having said that, there were no patients in the PPCI trial that came to us with a history of carotid artery disease, so it wasn't a concern for us in this study.
Dr Tim Gardner: That would be one point that I would make that we probably should pay attention to patients who do come for surgery and have known significant obstructive extracranial disease, but I understand that you didn't specifically have those patients or were aware of those patients.
I think that this is a very useful study for us concerned about the possibility of inducing cerebral injury with cardiopulmonary bypass. To some people it's sort of counterintuitive that increasing perfusion pressure didn't improve the tolerance of patients to cardiopulmonary bypass but that's why you did the study. I think it's a very notable and important report that's going to be in circulation.
The significance of these "silent infarcts" is merely something that we have to sort of sort out. I know you said that silent infarcts, as I agree, are associated with or presumed to be predictive of later cognitive dysfunction, dementia and so on. It really is a concerning message if that's the main message that comes out of these imaging studies. Because these are patients that, obviously, didn't have heart surgery for no reason, there was obviously a compelling indication for patients to have it.
You would hate to re-ignite this concern as we had in and around year 2000 when the group at Duke was talking about writing about patients who had cognitive decline after cardiac surgery, were going to end up being demented five or 10 years down the line, so, that's from the perspective of a cardiac surgeon. Let's stick with the evidence but let's follow-up and see how predictive these silent infarcts are and what the consequences are long term. Do you think that's fair, Anne? Am I making a fair statement?
Dr Anne Vedel: I absolutely do think it's fair. And for a cardiac surgeon as yourself, I would find it very interesting to see that these kind of studies are also conducted in TAVR patients where you have sometimes a 200% incidence of these silent strokes.
I mean you have a good taste as a cardiac surgeon if you only see them in 50% of your patients, understand me correctly, but I don't necessarily think that this high incidence, it's high, yes, but compared to other patient groups, such as TAVR patients, it's not necessarily that bad.
Dr Tim Gardner: Right. Anne, I don't know whether you've seen the editorial that's going to accompany your paper, but it's very good. It's very supportive of your study and has some good comments. You'll be pleased with the editorial, I believe, if you haven't seen it.
Dr Anne Vedel: Thank you very much. I'm happy to hear that. I know we do things a bit controversially over here in Copenhagen, compared to many centers in the U.S.
Dr Tim Gardner: That is not what the editorialists think. An anesthesiologist from Stanford and a neurologist from Penn, they have a very good commentary on your study and the whole field, so you'll be pleased.
Anne Vedel: I'm very happy to hear that. Thank you.
Carolyn Lam: Well, listeners, I'm sure you learned a lot. Thank you for joining us today, and don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore. Does NT-proBNP-guided therapy improve outcomes in acute decompensated heart failure? Well the Prima II trial results are coming right up after these summaries.
Is hospital volume a good structural metric assessing the quality of care in heart failure? Well, in the first original paper this week from Dr. Kumbhani and colleagues at UT Southwestern Medical Center, authors determined the relationship between admission volume, process of care metrics, and short and long-term outcomes admitted with acute heart failure in the Get With the Guidelines-Heart Failure registry, which has linked Medicare in patient data at 342 hospitals.
They found that lower volume hospitals had worse adherence to important heart failure process measures, than higher volume hospitals. There was no association between risk adjusted in-hospital mortality and hospital heart failure admission volume among older adults.
After adjusting for adherence with process measures at discharge, annual heart failure admission volume had a minimal association with mortality, and readmissions up to six months post-discharge. Thus, rather than focusing solely on hospital volume, hospital profiling efforts should perhaps focus more on participation in quality improvement initiatives, adherence to process metrics, and risk standardized outcomes.
The next study describes the association between air pollution and heart disease mortality in the United States, with a focus on whether the association differs by race and ethnicity. First and corresponding author Dr. Jennifer Parker from the National Center of Health Statistics Centers of Disease Control and Prevention and her colleagues use data from the 1997 to 2009 National Health Interview Survey linked to mortality records through December 2011 and the Annual Estimates of Fine Particulate Matter or PM2.5 as an index of air pollution.
They found that the association between air pollution and heart disease mortality in this national sample was elevated and similar to estimates found in prior studies. After controlling for social demographic and geographic factors, the associations between air pollution and heart disease mortality for non-Hispanic black and Hispanic adults were not statistically significantly different from that of non-Hispanic white adults.
Thus, this study supports the application of findings from prior studies of air pollution and mortality, albeit largely from non-Hispanic white adults, but to other races and ethnicities in the United States.
The next study suggests that large cardiac muscle patches engineered from human induced pluripotent stem cells may be a reality. First author Dr. Gao, corresponding author Dr. Zhang from University of Alabama at Birmingham generated human cardiac muscle patches of clinically relevant dimensions of 4 x 2 centimeters and they did that by suspending cardiomyocytes, smooth muscle cells, and endothelial cells that had been differentiated from human-induced pluripotent stem cells in a fibrin matrix and culturing this construct on a dynamic platform.
The results from in vitro assessments of calcium transience, action potential propagation, and forced generation, as well as the presence of intercalated disc-like structures, suggested that cardiomyocytes matured in these human cardiac muscle patches. During the 7-day dynamic culture period. When transplanted onto infarcted swine heart, measurements of cardiac function, infarct size, wall stress all improved with no increase in arrhythmias.
Changes in the expression profile of myocardial proteins indicated that the human cardiac muscle patch transplantation partially reversed abnormalities in sarcomeric protein phosphorylation. Collectively, these observations indicate that human cardiac muscle patches can be successfully generated and may improve recovery from ischemic myocardial injury.
Does a second arterial conduit improve outcomes after multivessel coronary artery bypass grafting? Well, in the next study from first author Dr. Goldstone, corresponding author Dr. Woo, from Stanford University and their colleagues used a clinical registry including all 126 non-federal hospitals in California to compare all-cause mortality, and rates of stroke, myocardial infarction, repeat revascularization, and sternal wound infection between propensity score matched cohorts, who underwent primary isolated multivessel coronary artery bypass grafting with the left internal thoracic artery, and who received a second arterial conduit or a venous conduit between 2006 and 2011.
The authors found that receipt of a second arterial conduit was associated with lower mortality, and at first cardiovascular events, compared with receipt of a venous conduit. The survival benefit associated with the use of a second arterial conduit extended to patients up to 78 years old. As a second arterial conduit, the right internal thoracic artery offered no benefit, compared with the radial artery, but it was associated with an increased risk of sternal wound infection.
These findings therefore suggest that surgeons should perhaps consider lowering their threshold for using arterial grafts and that the radial artery may be the preferred second conduit.
That wraps it up for our summaries. Now for our future discussion.
NT-proBNP and natriuretic peptides in general, have really become mainstay in management of heart failure, in the diagnosis, in the prognostication, but questions still remain regarding NT-proBNP-guided therapy. We heard about the guided trial in chronic heart failure just reported last year, and this year, in fact this week, in this week's journal, we're about to hear about PRIMA II trial in acute heart failure.
And how NT-proBNP was tested as a potentially guiding strategy for the management of acute heart failure. I'm so pleased to have the corresponding author with us, Dr. Wouter Kok, from University of Amsterdam, as well as our Senior Editor Dr. Biykem Bozkurt from Baylor College of Medicine. So welcome both of you, and Wouter may I just jump straight in it?
PRIMA II means that there was a PRIMA I trial, so could you just briefly tell us a bit about PRIMA I and the rationale for PRIMA II?
Dr Wouter Kok: Well the PRIMA II was an in-hospital guiding therapy that was preceded by the PRIMA II, it was a chronic heart failure patient population and one of things that we noticed in PRIMA I was the lack of effect of trying to reach a percentage drop in chronic heart failure patients. Why is that? Is that because there is a long time before you can achieve a therapy adjustment? Or is it something else? And shouldn't we start before patients are discharged from hospitals?
So the idea was born to do an in-hospital guiding study instead of chronic heart failure patients study.
Dr Carolyn Lam: Interesting. And could you tell us briefly, the design of PRIMA II and your findings?
Dr Wouter Kok: So the PRIMA II was designed based on the previous publication of several authors indicating that a 30% reduction in NT-proBNP would be a good target for heart failure therapy. Now, we first asked ourselves the questions, whether we should put this target in front of the hospital admission, so in the first 2 days or perhaps at the end of the hospital admission? And the 30% reduction was validated only for discharge purposes, so but we also tried to establish whether we could precede this date a little bit before discharge, but it appears that you cannot precede it too much.
So you cannot do it at day 3 or day 4, when patients are not stable. Because then you may expect a rise in proBNP again before discharge, and then you already ran the rise patients to discharge. So we decided to do it at discharge. At least 1 or 2 days before discharge, when patients would be clinically stable. And this definition of clinical stability was important because there should be one guideline for doctors to say, OK this patient has been treated well, or not.
Dr Carolyn Lam: Interesting. And so patients were randomized only after clinical stabilization, though in hospital after an acute decompensation, right? And then maybe the randomization arms, and the results please?
Dr Wouter Kok: Yeah, so the patients were randomized about day 7 or 8 after clinical stabilization, and day 3, but also patients at day 9, but when they were stable, they were randomized. And then the proBNP was measured, and when it was not reduced more than 30% they were guided. And when they were reduced more than 30% they were not guided but they were made ready for discharge.
So this was the randomization group. And the conventional group, the NT-proBNPs were measured at the randomization, and also at discharge, but nothing was revealed to the doctors. So it was only as a comparison for example, in the number of days necessary to wait before discharge, if this would influence the results.
The main finding is that the end point was negative for total mortality after 6 months, in combination with heart failure readmissions. So there were about 36% end point in both groups.
Dr Carolyn Lam: Yeah Wouter, you know, we've just come from the guided trial that was so soon neutral and infect, ended early and that was in the chronic heart failure setting so very different from what you tested in PRIMA II. Congratulations first of all for a beautifully done study.
But may I just ask, because in guided it was mentioned repeatedly that perhaps even the control arm was treated so well because these were such specialized centers. So what kind of centers took part in PRIMA II?
Dr Wouter Kok: We started at centers in Amsterdam, they were all very well educated in heart failure treatments, and all were using proBNP before the study started, so they were experienced in interpreting proBNPs. Because we had too little centers, and the inclusion rate was not so fast, then we asked other centers to participate, and we asked 2 for instance in Barcelona and Porto in Portugal, which helped us to complete the trial.
Dr Carolyn Lam: Oh that's really nice. And the design is really quite special, and I'm so appreciative that you took the time to explain that they were randomized only when stabilized.
Biykem, what do you think of that?
Dr Biykem Bozkurt: It's a fascinating trial, I have to congratulate Wouter and his colleagues. The number one very important finding I think is, about two-thirds of the patients before randomization are able to achieve reduction of NT-proBNP more than 30%. So subsequent to that in the guided therapy we're able to achieve maybe an incremental additional 15% adding to about, I think 80% of the patients initially randomized to the NT-proBNP arm. Achieving a reduction more than 30%. So overall, if the patient's naturally before randomization, achieve a reduction NT-proBNP, two-thirds of the time, pushing it further, trying to achieve a further dry state, by randomization does not appear to make any changes in readmission rates, or mortality at six months.
So this very important finding is the majority of the patients on conventional strategies are able to be decongested and achieve clinical stability. Now the other important finding is, I think about 17-20% of the patients regardless of what we do, do not demonstrate this significant drop in their NT-proBNP levels. Which I call as a non-responder team, which is a fascinating group of individuals. So we have the yin-yang, individuals may actually demonstrate that they're responsive. And when they're responsive, then the majority of the patients do demonstrate a reduction by more than 30%, and even if we push it further by targeted therapies, don't make a difference in outcomes.
About 17-20% regardless of what we do, do not respond, and from former studies we know that those patients are associated with worse outcomes. The other important finding I think, is what changed in the study? What medications, what therapies were changed? It was fascinating from Wouter's group to recognize that there was a little, significant, but a little increase in the ACE admission prescription. But there was also an interesting finding in the guided therapy, that the beta blocker used was slightly lower.
That raises a question of if we were to just chase the numbers, meaning try to just target therapies according to the NT-proBNP levels, whether we would see some unintended consequences such as reduction in medications, just because the numbers may be going in one way or the other. This is acknowledged in Lynne Warner Stevenson's editorial that will be accompanying the paper. And the editorial is very nicely titled "Getting to Dry". So I found that fascinating to recognize that the therapies, when especially the conventional arm is treated well, did not differ.
As was the case in the guided trials. When you treat the patients very well, as was seen in this trial, there was not much of a difference. But again trying to treat a number by targeted therapies may not result in all the optimization that as we envisioned to see. And the third concept is the length of stay, of course in the U.S. is a major issue, and I do realize when we're trying to treat a number, sometimes the length of stay may end up being longer. And I do realize that perhaps in the targeted therapy group, the length of stay was a little bit longer, maybe Wouter can comment on that.
But overall it didn't result in any change in outcomes, or was not associated with any of the outcomes. So that was also an interesting finding. Because we tend to focus a lot on length of stay, but interestingly I guess by secondary analysis, there was no association with the clinical outcome.
Dr Carolyn Lam: Wouter, would you want to comment the length of stay concept?
Dr Wouter Kok: Well it's indeed in the guided group, and the randomized group who were trying to attain the 30% NT-proBNP reduction, the length of stay was longer. Something about 11 days, compared to those who did not need guiding was about 8 days. Still long compared to U.S. standards, but it was the same in the conventional group, so about 9 days is respective of whether they reached a 30% reduction or not.
So here is the clinical experience. So the patient cannot tell whether he is reduced more than 30%, and the doctor isn't able to tell either. Because then the admission would have been longer probably. But trying to lower the 30% more, has some effect. There's little effect, but it has some effect. And then they have to do a sort of economic analysis, is 3 days longer in hospital, is it worthwhile to do that compared to for example reduction in admissions that you receive? This is a small population, only one-third of the patients who need guiding, and more than half of them you will reach somewhat more reduction than if you don't try at all.
So for us, that is the main result of the trial, if there is a signal, then it is still possible to do something, and the other remark about whether you increase or decrease medication, that's something that was discussed in the guided study too. So what is the best for the patient, is that the maximum medication or not, and we see for example, that if we reduce beta blockers, in some patients then some will improve in their functioning and also in the BNP.
So it's not always necessary to increase and increase medication. So that was also some signal that we tried to do some more research in. What is the target? Is the target a guideline, saying that more medication is better? Or is the target itself for proBNP a possibly better target than that?
Dr Biykem Bozkurt: And the other interesting finding for that, there were no differences in chemo concentration levels in the guided versus non-guided groups. And last point that I wanted to make is the larger BNP reduction was amongst the individuals who did not require any guidance in successfully guided versus unsuccessfully guided, compared to those who did not need the guidance.
Those who were able to achieve the more than 30%, when you look at the magnitude, meaning amongst the individuals who are going to naturally respond to therapy, the natural responders, the decrement, or the decrease in the BNP levels are larger, than those ones we're trying to push. So that was another interesting, fascinating ... I was almost thinking whether that in the future we should look at responsiveness of patients, if we see they're responders then try to target their therapy or not.
So in a sense the non-responders, they now respond regardless of what we do. Responders may be gaugeable or titratable, or maybe with the precision respond to targeted therapies that almost have a dichotomous approach. What do you think about that Wouter?
Dr Wouter Kok: I say yeah we made a big mistake in thinking that more than 30% for patients who still needed guiding would be the same as rating the more than 30% without guiding. But the difficulty you have in reaching the 30% is already indicative somewhat less increase in prognosis than you will reach it spontaneously.
So we have to adapt our numbers for the trial, so it is recalculation that how many patients we would need to be successful in our trial, and that would be 600 patients in every arm, and then even then, you have to recalculate some of the effects that you will have to reach them. Perhaps the mid-range risk group is a better risk group to target than the highest risk group. That's something that we have to think about too.
Dr Biykem Bozkurt: I think we will probably need to focus on individualization, I almost feel as though we will need to learn from the cancer trials, and see whether we could try to target rather than you know the population based clinical trials, trying to do the targeted therapies. Maybe fine tune the ability to precisely target, and of course that requires a little bit more layering of the markers and or a signal that we're going to be profiling in the individual.
So I don't think it's the end of targeted therapies, perhaps requiring a little bit of a more precision, and maybe individualization. But I am fascinated by first realizing it's a responder, and then maybe trying to accelerate and or optimize therapy, perhaps especially when we are forced or driven by administrative concepts such as length of stay or others. So making sure that maybe these variables, these biomarkers may help us recognize that maybe we haven't achieved that appropriately dry state yet.
But those all need to be determined, of course, by future trials, so far targeted therapies both in the acute and in the chronic does not seem to result in implementing outcomes.
Dr Wouter Kok: Well and the next step for us is to try and think how can reduce proBNP in all patients, we tried it with medication, but didn't do that much of catheterizations for those who were ... there were 50% of patients who were ischemic so why don't we do much of these catheterizations now days. So that's something we're thinking about how can we improve these patients? What are we missing?
Dr Carolyn Lam: Yeah, if I could add my two cents. So Wouter mentioned finding the right therapies that can effectively reduce NT-proBNP safely, and well you mentioned choosing the right patients to use this in. And if I may, you know, just adding perhaps the right settings as well. Because it's well known that not all of us take care of heart failure patients the same way. And maybe there are settings where having a number to guide us may be more useful than others. But what do you do? You know, we wait for more data, but in the meantime, just congratulations. Heartfelt, heartfelt congratulations Wouter for a beautiful study, thank you so much for the privilege of publishing it in Circulation.
Thank you for being on this podcast, and listeners don't forget to tune in again next week.
Dr. Carolyn Lam: Welcome to Circulation On The Run, your weekly podcast summary and backstage pass to the journal and its editors. I am Dr. Caroline Lam, Associate Editor from the National Heart Center and Duke National University of Singapore.
Can we reverse the cardiac effects of sedentary aging? Well if you're curious, you have to read the feature paper in this week's journal, as well as listen to the upcoming discussion of a trial that addresses this issue. All coming right up, after these summaries.
Desmond mutations are known to cause skeletal and cardiac muscle disease, and also recently has been described in patients with inherited arrhythmogenic right ventricular cardiomyopathy or dysplasia. In today's first original paper, however, authors identified a novel Desmond mutation in a large Spanish family with inherited left ventricular arrhythmogenic cardiomyopathy or dysplasia, and a high incidence of, at first, cardiac events.
First in corresponding author, Dr. Bermudez Jimenez from Granada, Spain, describe for the first time the largest family to date with a single Desmond mutation with a phenotype of left dominant arrhythmogenic dysplasia in the absence of skeletal myopathy symptoms and atrioventricular conduction disorders and supported by strong clinical and functional data. In a series of elegant experiments using explanted cardiac tissues and mesenchymal stem cell derived cardio myocyte from the family members, the author showed that the pathogenic mechanism probably corresponds to alteration in Desmond dimer and oligomer assembly and its connection with membrane proteins within the intercalated discs, thus Desmond mutations should be suspected in patients presenting with a cardiomyopathy characterized by mild left ventricular systolic dysfunction and/or dilatation, fibrosis, ventricular arrhythmias and a family history of sudden death.
The next study is the first large scale report examining the incremental risk of surgical aortic root enlargement in patients undergoing aortic valve replacement.
First author Dr. Rocha, corresponding author Ouzounian from University of Toronto and their colleagues sought to evaluate the early outcomes of patients undergoing aortic valve replacement with or without surgical aortic root enlargement.
Now aortic root enlargement allows for larger prosthesis implantation and maybe an important adjunct to surgical aortic valve replacement in the transcatheter valve in valve era.
Among more than 7,000 patients undergoing aortic valve replacement at a single institution from 1990 to 2014, the authors observed no incremental risk in post-operative mortality or adverse events following surgical enlargement of the aortic root as compared to aortic valve replacement alone. They therefore concluded that surgical aortic root enlargement appears to be a safe adjunct to surgical aortic valve replacement in the modern era.
The next study suggests that in patients with acute coronary syndrome and an LDL cholesterol above 50 milligrams per deciliters, health care providers should consider adding ezetimibe to statins, particularly in two patient subgroups.
First in corresponding author Dr. Giugliano from the TIMI study group at Harvard Medical School in Boston, Massachusetts and his colleague explored outcomes stratified by diabetes in the "improve it" trial where patients with a recent acute coronary syndrome were randomized to ezetimibe versus placebo on top of backgrounds in the statin.
They found that patients with diabetes derived significantly greater relative and absolute benefit with the addition of ezetimibe relative to patients without diabetes. This enhanced benefit was driven by reductions in acute ischemic events including myocardial infarction and ischemic stroke in diabetics, while non-diabetic patients who were more than 75 years of age or who had a high risk score also significantly benefited from the addition of Ezetimibe to Simvastatin.
These benefits of Ezetimibe were achieved without an increase in safety events compared to placebo. Thus, the two patient subgroups of acute coronary system who are likely to achieve greater benefits with the addition of ezitimibe include: one, patients with diabetes, and two, patients without diabetes who have a high risk score.
The final study provides insight into sudden cardiac arrests in the young and the potential contribution of standard cardiovascular risk factors to this risk, even in the young.
First author, Dr. Reshmy Jayaraman, corresponding author Dr. Chugh from Cedars-Sinai Medical Center in California and their colleagues, prospectively ascertained 3,775 individuals who suffered sudden cardiac arrest between the ages of 5 and 34 years in the Portland, Oregon Metropolitan area and who were also followed up for 13 years. They found that 5% of cases occurred in young residents between the age of 5 and 34 years.
Among the young, there was an unexpectedly high prevalence of classical cardiovascular risk factors, such as obesity, diabetes, hypertension, hyperlipidemia and smoking. In fact, one or more risk factor was observed in 58% of cases, with obesity being the most common.
Less than a third had warning symptoms prior to their lethal event and sports activity was a trigger in only 14% of young cases. Thus, standard cardiovascular risk factors, especially obesity, may play a larger role in sudden cardiac arrests in the young than previously recognized. This suggests the potential role of public health approaches that screen for cardiovascular risk factors at earlier ages.
And that wraps it up for our summaries, now for our feature discussion.
Oh boy, today's featured discussion is gonna make everyone listening fall in love with exercise and seriously get off your chair right now as you listen to this discussion.
It's about how exercising may reverse cardiac aging and I am so delighted to have with me none other than the corresponding author, Dr. Ben Levine from the institute of exercise and environmental medicine at Texas Health Presbyterian and UT Southwestern, as well as Dr. Jarett Berry, and he's our dear associate editor from UT Southwestern.
Ben, I have been dying to have you on this show, so welcome and please, tell us what you did.
Dr. Ben Levine: Thank you very much, it's a pleasure to be here Carolyn, thanks for inviting me to talk about it. As you know, our lab has been particularly interested in the components of aging that are related to senescent versus those that are related to senescence activity.
Perhaps the most dramatic reason that we're interested in this, I'm just gonna give you a little bit of background, if you don't mind, comes from one of the most important studies ever done in our field, that was done in Dallas in the mid-1960s. It's called the Dallas Bedrest and Training Study.
At that time, my mentors, G Blomqvist, Jerry Mitchell, Bengt Saltin, took five young men, put them to bed for three weeks and then trained them for two months and virtually everything we know about the adaptive capacity of the circulation to exercise starts without study.
I was only ten years old, so I really had nothing to do with it, but 1996, 30 years later, we found those same five guys and brought them back to Dallas to study them again.
Now, these are the most intensively studied humans probably in the history of the world. 78 pages of circulation in 1968. What we found was quite amazing. We found that not a single one of those five guys was in worse shape 30 years later, than they were after three weeks of bed rest when they were in their 20s.
So, three weeks of bed rest was worse for the body's ability to physically work than 30 years of aging. And so, we sort of launched off that in a series of experiments, trying to figure out when in the aging process does the shrinking and stiffening of the heart develop, that is the sine qua non. if you will, of the cardiac aging. So, when does it start? How much exercise do you have to do to prevent that?
We did one interesting study where we compared a group of very highly selected seniors, all aged around 70, who were healthy, but did no exercise, compared to a group of elite Masters Athletes. Amazingly, the healthy seniors, their hearts got smaller and it shrunk and they got stiffer and the athletes had hearts that were indistinguishable from healthy 30 year olds.
So, a lifelong training at the level of being an elite athlete completely prevented that aging response, which is really interesting scientifically, but not a very good public health measure.
So, we then asked how much exercise do you need to do over a lifetime to preserve the compliance, the youthfulness, if you will, of the circulation, and at times, they act like you need to do about 4 or 5 days a week over a lifetime. 2 to 3 days a week didn't do anything. 4 to 5 days a week did almost as much as being an elite competitive athlete. So, now we've got the dose. 4 to 5 days a week.
We said, "okay, if we do that, can we reverse cardiac aging once it's occurred?" So, we took our healthy sedentary people and we also looked at a group of HFpEF patients and we trained them for a year, at the right dose, using high intensity exercises. We made them fitter, but we couldn't touch their cardiac or vascular stiffness. Quite disappointing actually.
Last thing then, we said "okay, this leads up in to our current study maybe, just maybe, if we pick the right sweet spot in time, when the heart is just beginning to stiffen in that late middle age period and deal the right dose at the right time for a long enough period, we could reverse the effects. And, that's what we did. We took 60 people, healthy, middle aged, 45-64, mean age around 50. We randomly assigned them to two years of exercise training or two years of yoga, balance, flexibility, and we did 2 light heart caths. We measured their cardiac compliance directly invasively and we showed that our 2 year training program, which included high intensity intervals, reversed the effects of decades of sedentary aging.
Dr. Carolyn Lam: Wow, Ben, you know, no one tells the story like you and I have to tell you, I've been a fan of your work, citing it since I was 10. Thank you so much for this amazing contribution to the Journal this week. I just know everybody's asking questions like "So, you've given us when to start, you given us the dose, but we want to understand a bit better, what do you mean high intensity, how many minutes and what exactly." Could you give us an idea?
Dr. Ben Levine: Sure. There are multiple different ways to go about doing HIIT or High Intensity Interval Training. And there's no magic to intervals. Intervals just allow you to do something for a shorter period of time and harder than you could do for a longer period of time. That is the strategy that athletes use to go faster and stronger and higher, because the body adapts to the load that's placed on it.
Interval training, what I like, is based on an old Norwegian ski team workout. It's called the "4x4". What that means is 4 minutes at 95% of your maximum followed by 3 minutes of recovery, active recovery, repeated 4 times. So, basically, you go as hard as you can go for 4 minutes and at the end of those 4 minutes, you should be ready to stop. Typically, your heart rate will drift up towards 95% of maximum or so. Then, at the end of the 3 minutes of recovery, you should be ready to do the next interval.
As it turns out, that's extremely effective training stimulus. Not just for healthy people or athletes, for the patients with hypertension and with heart failure.
Dr. Carolyn Lam: I noticed that you have to screen over 260 individuals to finally get your 60, so how doable is this and what was the compliance?
Dr. Ben Levine: Right. You have to remember that out of those 260 individuals that we screened, the majority of them were excluded up front because they had hypertension or if they were obese or they already had heart disease. So, the first round of screening was making sure we're getting people of the right age and were healthy. And, then another fraction, say 40 of them or so, didn't wanna undergo two light heart catheterizations. And, I get that. We were pretty pleased that somebody volunteered to do it, but you know, it's an intense commitment. People have to be willing to be randomized. So, they couldn't say "Well, I wanna do your study, but only if I get randomized to exercise", that was not acceptable.
So, everybody had to be prepared to be randomized to either yoga or the fitness training and the yoga, it makes people feel better, it's relaxing. I think it provided that clinical equipoise and it ensured that even the controlled patients had close contact with our research team.
Then, what we had was, on average 88% of the prescribed sessions were followed by our exercisers and a fraction of them, 15 or 20%, actually did 100% of their prescribed sessions over two years, didn't miss a single one.
Dr. Carolyn Lam: So, Jarett, have you started doing that yourself now?
Dr. J Berry: I tell you, I pried my kids out of bed last summer, to go do 4x4s and get them ready for cross country. I talked all about Ben Levine and told my kids that we were doing what Dr. Levine recommended. That didn't help too much, they found it rather challenging. It was interesting that the VO2 plateaus a little bit at that 10 month mark, when you guys backed off on that additional interval training. Do you think that the plateau is just a limitation of the training effect or do you think that something that has to do with the lower level of interval training at that time?
Dr. Ben Levine: You know Jarett, I think that's a fascinating question and it's one of the things that really surprised me. So, Jarett pointing to the fact that at that 10 month mark, we measured VO2 max, we didn't cath them, but we did an Echo, and it showed that from 10 months to 2 years VO2 max didn't increase very much.
There was a dramatic increase from baseline to 10 months. It took 3 months at that peak dose. But then, when we dropped one interval and did the same thing every week for 2 years, there wasn't an influence of time. The heart didn't continue to get bigger, the stroke volume didn't continue to enlarge.
I think it highlights a critical part, an essential element, to that exercise training and that is, doing the same thing, over and over again doesn't get you fitter. If you wanna get fitter than you are, you have to change things around, you have to increase the load. So, I think that if we had wanted to make them even fitter than they were at 10 months, we'd have had to either kept that second interval or added another one or increase the duration of some of the base training sessions.
It's really interesting to me, that they didn't continue to improve simply on the basis of time. That surprised me.
Dr. Jarett Berry: Yeah, cause you wonder. You think about, the guidelines suggest moderate intensity exercise, which is obviously much lower intensity than what you're talking about with this interval training, but very little guidance with regard to interval training.
Your data here obviously suggests that it's not just getting off the couch and doing something, and not just doing a decent amount, it seems to suggest that the interval training component may be a secret ingredient that might be most helpful, at least for those patients who can tolerate that level of training.
Dr. Ben Levine: Yeah, I think that maybe it's the secret sauce, Jarett, but I think, you do have to ask yourself, what is the goal of training and what is your objective outcome? What you want is to reduce cardiovascular mortality. I think we would all agree that you get the biggest bang for your buck by going from sedentary to active. And, the mechanism of that is uncertain, but could relate to autonomic function or clotting or improving stabilization of endothelium or other risk factors, inflammation, who knows, there's a lot of different candidates. So, I think that particularly for people who are at the highest risk for heart failure, either from their family history or other risk factors, like hypertension and diabetes, those are the ones who were likely to get in a special benefit on altering cardiac structure.
That's why I think our data is still an important poll. We didn't really know why do you get the biggest bank for your buck with a little training, but if you really wanna prevent heart failure, you gotta do more.
In our data that we did partnered with the Cooper Clinic and looked at people who had done the same number of exercise sessions over 25 years. None, 2-3, 4-5 or 6-7, over 25 years, we saw virtually no effect of 2-3 days a week of what we call casual training on anything we could measure, related to cardiac structure. Their vascular stiffness was the same as people who were sedentary, their cardiac stiffness was the same as people who were sedentary. They were a little fitter and perhaps there were other important differences that are related to just improving immortality, but you have to get past that low to moderate dose to have the structural effects on the circulation.
Dr. Jarett Berry: These are really great points here, Ben. I want for our listeners to hear you comment a little bit more on the primary outcome and how you guys measured stiffness, because I think in addition to the level of training, it's also the approach and the phenotype that you collected to measure this and I think it would be helpful for you to walk us through that a little bit and how you guys measured stiffness.
Dr. Ben Levine: We used an old physiological technique called "Lower Body Negative Pressure". We first let the subject settle down, we measure a variety of cardiovascular variables, cardiac output, and we do an advanced ECHO imaging and some arterial stiffness measures and after about 40-45 minutes or so, we'll measure the pulmonary capillary wedge pressure, that's what we use as an index, and plus ventricular and diastolic pressure. We'll do 3D ECHO volumes and then we unload the heart by doing Lower Body Negative Pressure. We basically seal the subject in a box at the iliac crest and turn on a vacuum cleaner and suck blood into their venous capacitance. It's a very simple way to unload the heart.
In contrast to people who do put in conductants or reflectant catheters and occlude the IVC and do pressure volume rudes, we have taken a little bit of a different approach. I do steady state and diastolic pressure volume curves. So that means, we look at the pressure and volume in the heart at baseline at two different unloading levels. So, let's say the baseline ledge is 10. The first level of LBNT of minus 15 will get it down to 6 or 7. The next level of minus 30 gets it down to 2 or 3. And, so we get a nice unloading of the heart and we're able to establish a steady state, which is probably more afunctional than a release of an IVC occlusion.
Then, we let go of the suction, everything returns to normal. We repeat our baseline measures and then we give the rapid saline infusion. When I say rapid saline, I mean 15 and 30 mls per kilogram, that's at 200 mls a minute. That's a big volume infusion, but we'll give those doses and we'll raise the ceiling pressure from 10 at baseline to 15 and then 19, 18, 19. So, we get a large physiologic range of the diastolic pressure volume curve, and then we'll fit that to an extremely widely accepted exponential equation, which allows us to calculate the overall stiffness of the heart, the diastolic component, and then we'll do a few other things, we'll measure distensibility , which is the volume at any given pressure and DPDV, the change in pressure for a given volume, which is the hansen float to the exponential curve fitting.
Dr. Jarett Berry: Can you comment a little bit about what this means for how this is distinguished perhaps from maybe more conventional non invasive measurements of cardiac stiffness?
Dr. Ben Levine: I think the most important thing to realize is that, cardiac compliance is dynamic. It depends on the volume at which you're making that measurement. So, as you unload the heart, any heart, even the stiff heart, it gets more compliant, and as you load the heart, even a compliant heart, it gets stiffer. Part of that is a function of pericardial constraint, as well as myocardial stiffness.
The whole idea that there is a measure of diastolic function that you can measure by ECHO that is load independent is frankly an oxymoron, because, diastole is load dependent. I think the ECHO measurements are interesting and useful, depending on what you're trying to find out, because there are many different aspects of feeling and diastolic suction and diastolic stiffness. All of which influence how well the heart feels at rest and during exercise.
Dr. Carolyn Lam: I have to ask you one last question. I am so pleased that you included at least 52% women. Were there any differences by sex?
Dr. Ben Levine: Of course, Carolyn, it's critical to include women, since they're 50% of the population. We've been very interested in their training responses in men and women at different age groups in many of our other studies. What's interesting is that in premenopausal women, there's a quite clear distinction in how women respond to training. They don't hypertrophy as much, even for the same stimulus, heart beats a heart beat, over a year, there's a much less hypertrophic response to premenopausal women than young men.
We didn't see anywhere near that difference in our mostly postmenopausal middle aged men and women. We didn't have enough power to clearly be confident that there was no difference, but when we tried to test that hypothesis, whether there was a different response in men or women, we could not detect a difference.
Dr. Carolyn Lam: That is a good thing. So, women out there, you heard it from Dr. Levine. We got to exercise too. High intensity. All the time.
Thank you audience, for listening today. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore.
Today's feature paper is about statins, and it's the first population-based study to show a dose-dependent benefit on amputation and survival in peripheral artery disease. Very important data and a very important discussion coming right up after these summaries.
The first original paper this week indicates for the first time that the natural history of coronary stenosis is better predicted by physiologic information by FFR, or fractional flow reserve, than by anatomic information from angiography. First author, Dr. Ciccarelli, corresponding author, Dr. DeBruyne, from OLV Hospital in Belgium compared the values of angiographic diameter stenosis and of fractional flow reserve in predicting the natural history among 607 patients from the FAME 2 trial who had documented stable coronary disease and in whom no revascularization was performed. The primary end point was defined as vessel oriented clinical end point at two years, and this was a composite of prospectively adjudicated cardiac death, vessel-related myocardial infarction, vessel-related urgent and non-urgent revascularization.
The overall results showed that FFR predicted the natural history better than diameter stenosis. In addition, among the stenosis with mismatch between diameter stenosis and FFR, more than half had a low FFR in the presence of an angiographically mild stenosis and the rate of primary outcome was higher in those with reduced FFR regardless of whether diameter stenosis was significant or not. The take-home message is, therefore, that measurements of FFR should be considered not only an angiographically intermediate stenosis but also perhaps a mild or severe stenosis by visual evaluation.
The next study provides population-based data on cardiovascular outcomes and risks after initiation of a sodium glucose cotransporter-2 inhibitor, or SGLT2 inhibitor. First and corresponding author, Dr. Udell, from University of Toronto, and his colleagues, performed population-based cohort study among type 2 diabetes patient with established cardiovascular disease and newly initiated on antihyperglycemic agents within the US Department of Defense Military Health System between 2013 and 2016. After propensity matching, more than 25,250 patients were followed for a median of 1.6 years. Initiation of SGLT2 inhibitors was associated with a lower all-cause mortality, lower hospitalization for heart failure events, lower major adverse cardiovascular events, but higher below-knee amputation risk. Findings underscore the potential benefits and risks to be aware of when initiating SGLT2 inhibitors. Importantly, it remains unclear whether the risk of below-knee amputation extends across a class of medications as the study was not powered to make comparisons among individual treatments.
The next paper reports results of the redefined trial, which is the first trial to study the effects of renin-angiotensin-aldosterone system inhibitors in adults with tetrology of Fallot and mild right ventricular dysfunction in the absence of severe valvular lesions. First author, Dr. Bokma, and corresponding author, Dr. Bouma from Academic Medical Center Amsterdam, and their colleagues, studied 95 patients in the redefined trial and found that 150 mg of losartan daily did not significantly improve the primary outcome of right ventricular ejection fraction change compared to placebo. There were no significant treatment effects on secondary outcomes of left ventricular ejection fraction, peak aerobic exercise capacity or NT-proBNP. However, in a post hoc analysis, losartan was associated with improved right ventricular ejection fraction in a subgroup of 30 patients with nonrestrictive right ventricles and incomplete remodeling. The conclusion is, therefore, that losartan had no significant effect on right ventricular dysfunction or secondary outcome parameters in repaired tetralogy of Fallot. Future larger studies may determine whether there might be a role for losartan in specific vulnerable subgroups.
The final study reinforces that vesicle trafficking plays an essential role in the signal regulation of pathologic hypertrophy and identifies a novel potential target in this process. This novel target is the transmembrane BAX inhibitor motif containing 1, or TMBIM1. First author, Dr. Deng, corresponding author, Dr. Li, from Wuhan University in China, and their colleagues, found that TMBIM1 expression levels were substantially decreased in both clinical and experimental hypertrophic hearts. Mechanistically, TMBIM1 interacted directly with tumor susceptibility gene 101 and accelerated the formation of multivesicular bodies to degrade activated toll-like receptor 4. Toll-like receptor 4 degradation in turn was essentially for the progression of cardiac hypertrophy. Importantly, expressing TMBIM1 in monkeys via lentivirus protected their hearts from aortic banding induced cardiac hypertrophy. In summary, these findings shed light on the role of vesicle trafficking in signal regulation during cardiac hypertrophy and provide a novel therapeutic target for treating hypertrophy.
That wraps it up for our summaries. Now for our feature discussion.
Peripheral artery disease, a disease that affects more than 200 million individuals worldwide and associated with a high risk of cardiovascular events and death and, of course, the much feared amputations. Yes, statin guidelines for peripheral artery disease are largely based on coronary artery disease or stroke data. Well, today's feature paper really addresses an important knowledge gap between statins, doses, amputation survival in peripheral artery disease. I'm delighted to have the first and corresponding author, Dr. Shipra Arya from Stanford University School of Medicine and, of course, our favorite, Dr. Josh Beckman, Associated Editor from Vanderbilt University.
Now, Josh. I understand there's a bit of a back story of how this paper came to circulation. Want to share?
Dr Josh Beckman: Oh, absolutely. First of all, I have to say that one of the jobs of an associated editor is someone who kind of goes antiquing in every single store. Every place I am where people are presenting really good science, I'm kind of scoping it out. I'm interested. I want to see what's going on. I like to talk to the people who are doing the work to see how they're thinking about it, and I was lucky enough to see Dr. Arya's presentation. I think it was at an ATVB meeting, wasn't it?
Dr Shipra Arya: That's right.
Dr Josh Beckman: I thought that this is an incredibly cool piece of work, and I basically hoped, I prayed, I asked. I said, "You know, maybe you should send this to us because we would really like to see the full manuscript," because inside I hoped that it would be just as impressive when it was written out as a full manuscript as it was when she was discussing it at the meeting. And, lo and behold, we were lucky enough that she submitted it to us and you can see the results online right now.
Dr Carolyn Lam: Indeed! Well put. Shipra, with that kind of lineup, please, tell us about your study and what you found.
Dr Shipra Arya: Thank you for that invitation to submit to Circulation because initially I wasn't sure if Circulation would be interested in my work, so it was really great to hear when Josh said that this is something that it would certainly consider. The basic premise was to try and find out whether high-intensity statins as defined by the 2013 lipid guidelines, they would also have limb protective effects for PAD along with reduction mortality. As you said in the introduction, most of the data comes from either coronary data or comes from small groups of PAD patients, but never from such a large population.
We identified about 150,000 veterans in the National VA database from 2003 to 2014 and excluded people who didn't have a diagnosis of PAD before 2003, and why this was such a labor of love was also to figure out how to identify the certainty that people had PAD and then getting into their pharmacy files and trying to parse out whether they were on high-intensity, low, moderate, or no statin. Initially, I had done the analysis of no statin, but then after review and discussion, it became clear that we needed a control group, which was people who were also on some guideline-directed therapy and not just no statin because they could be patients who were the noncompliant patients and who don't show up to the doctor's visits, and that's why they do poorly.
That's why we chose a control group which were on antiplatelet therapy, at least aspirin or Plavix, any other antiplatelet agent. Even in that comparison, we find that after risk adjustment, patients who are on high-intensity statin had a more than 30% risk reduction of amputation as well as about a 24, 25% risk reduction of mortality compared to people who did not take a statin but at least took an aspirin. Low to moderate intensity statins were also effective, about 20%. Risk reduction in both amputation and mortality, but high-intensity statins when directly compared to the low to moderate intensity statins outperformed them.
Just to be sure of our findings, we did it so many different ways. We did the Cox modeling. Then we did propensity matching that which person is more likely to receive the statin versus the other. Then we did subgroup analyses where we put people in different subgroups that people who had coronary artery disease as an indication, maybe that's why they were on these statins. But, people without coronary artery disease also same association [stack 00:11:12]. We were pretty confident in our findings, and that's why we sent it to Circulation.
Dr Carolyn Lam: Wow. You know, Josh, you are the best at putting papers like this into context and really expounding on the significant. Tell us, why did this catch your attention so much?
Dr Josh Beckman: Every time I think that statins have become just a standard part of therapy for patients with atherosclerosis, the first thing I noticed in this paper was that there were so many people who were still not on any statins or people who were on homeopathic doses of statins, and I can't understand how that happens. I think the mortality data was nice and consistent, but the amputation data is what really made a big difference. I'll ask Dr. Arya, but in my impression, the literature has been sort of back and forth as to whether or not statins really reduced limb outcomes. Your paper, I think, was clearly the largest sample that had taken a look at that question. Can you sort of separate out your papers from some of the previous work in that area?
Dr Shipra Arya: Sure. I would add that a lot of work about amputations has been coming out from vascular surgery data, and a lot of that work just focuses on short term outcome for limb loss. They look at 30 days. Maybe they'll go look up to six months to a year, but actually patency of bypasses, patency of vessels is a long-term phenomenon. Much like mortality that can happen years later, your amputation risk can happen years later, too. I think what separates us is the lifetime followup for these patients, and we are looking in a cohort of patients who are in this veterans' healthcare system so the data is automatically getting captured even if they get their care outside. Records do make it back and diagnoses do make it back. It's the VA [inaudible 00:13:03], and we did some sensitivity analysis to show that, yes, most of the veterans we have in [inaudible 00:13:09] actually get their care and have data being added continuously into the corporate data warehouse.
That was something I think that lent to the power of making the [sure 00:13:20] conclusion and that's where previous studies have not been able to show a significant association with amputation. The studies, if they are single center or they are focused from electronic medical records or perspective followup, either the patients get lost to followup or go see other doctors or other healthcare systems, and that information doesn't get back to the researchers, while mortality data you can get from Social Security Death Index or other sources. I think that's what makes the study different than other studies in this similar field in terms of followup.
Dr Josh Beckman: I don't think you're giving yourself enough credit. There's a whole bunch of things that make the study unique. One of the things that I was most taken with right upfront was the way that you defined peripheral artery disease for this population. There has been, as far as I know, at least seven or eight different definitions that people have used with administrative data to try and ferret out who has PAD, and in contrast to coronary disease and stroke, it's a much more complicated endeavor to do that. So, when I saw the way that you did it ... I'm going to say this in a way that I know is going to sound funny, but you made the complicated look really simple. Your definition is not something that required 3,000 lines of ICD-9 codes within inclusion and exclusion criteria and speaks, in my opinion, to the power of the large sample because, basically, they needed one ICD-9 code and either two ABIs, a visit to a vascular surgeon or procedural code. Now, I know that this definition comes from some of your work, so can you tell us how you derive this and then let's talk about what that means.
Dr Shipra Arya: Absolutely. We looked at practice patterns for patients with vascular disease across the VA, and most patients who undergo procedures for PAD, we can confidently say that they do have PAD. When we look at the specificity of just that occurrence, it's pretty high, like [90% 00:15:23]. Then what we did was we did some random sampling in the VA data, about 300 patients, and used different codes to see if patients came back to the vascular surgeon within ... We used 14 months because it's usually one year followup that most people prescribe, so whether they went two months before or after because the appointment hours. We found that that was again a high specificity of about 80%. Then, when you look at patients who come back with ABI followup. So, we looked at CPT codes for ABI. We found out it's like a 99% specificity. If you have ABI followup within a year, and we relaxed it to 14 months, you could be 99% confident that this patient does have PAD.
We just combined all those three together, and this is ... If Circulation is interested, I can send you this, too. We are working on this manuscript where we are giving researchers different algorithms that they could use to identify PAD because I wanted a more specific sample because I was looking at PAD outcomes. I wanted the PAD definition to be tight. Our specificity is greater than 80% combining all these three together, about 84%. We are fairly confident in this that, yes, these patients truly have PAD, so when we follow them up for outcomes, we can be confident in our results. If researchers wanted a more relaxed definition of PAD, they could use other algorithms that we are putting in that paper where they could say, "We will only use one ABI measurement, or we would use a combination of these."
Dr Josh Beckman: That brings up two points. You talk about this brings up the power of large data and the ability to tone down on people who really, truly, absolutely have PAD without any question. So, number one, are you worried that you're missing people that probably do have PAD and would benefit from therapy, and number two, do you worry that you're basically concentrating on the sickest right end of the curve of the group of PAD patients?
Dr Shipra Arya: Right. That's a great point, and I discussed that with my coauthors and mentors and we wanted to be sure about our outcomes and not want to include people who did not have PAD, and then we are kind of including the effect size of what we may find, but yes, these are truly what we are calling a symptomatic PAD, and I think I mentioned that in the manuscript somewhere, that we probably would be missing people who are asymptomatic and not really being followed up. If we extended this analysis to people who are not regularly being followed or being under surveillance for their PAD, the results could be different. So, yes, it does not generalize the whole of that population. If we had gone that route and relaxed our inclusion, my worry was that we would get ... Because of large data setting up, as you say, if we include a bunch of people who are truly not PAD, we would be a [threading 00:18:17] risk in non-PAD patients.
Dr Carolyn Lam: Josh and Shipra, I loved the paper, but after this discussion I'm even more in love with the paper and impressed, so I think I just have a question for both of you. Is there any excuse not to give statins now? Do we actually think a trial is going to come on this topic? Is this the best data that we have? Is it going to enter guidelines? What do you think?
Dr Josh Beckman: I can give you my opinion first, if you want, because you're the person who actually has control of all the data. I would say this. I think it's been well known that statins should be used in all the patients with PAD for their cardiac outcome. My guess is that there are two things that are going to happen that are going to make people consider statins for limb outcomes.
One, data like this and there's never going to be a trial, a prospective randomized trial at this point, I mean unless you disagree, but there's no way people will randomize to not statin. I think the second reason is the recent data on the PCSK9 inhibitor, evolocumab, which showed that on top of statins in PAD patients, there was a further reduction in limb events. I think we're heading towards getting the LDL to zero. It may take a couple more steps, but that's basically what's going to happen.
Dr Shipra Arya: I agree. I think there has been time and time again data that shows, especially those already data supporting the mortality benefit for larger cohorts of patients with cardiovascular disease including PAD. I think this study really nails down the limb protector effects of statins, and doing a trial of this magnitude would be very difficult to do because to get that would be effect size that you have. You would need a huge cohort of patients, and you probably won't find statin-naïve patients because you have already half the patients with PAD have coronary artery disease, as well. So, not every study needs a trial. Not every question needs a trial, in my opinion. I think that's the power of large data sets. I think the evidence is overwhelming, and I would agree with Josh.
Dr Josh Beckman: I have always had a hard time explaining to people who came to see me for legs problems that they have to take a drug for their heart. It's sort of a weird two-step that people have a hard time accommodating. Do you think by telling them that this drug will also save their leg that they're going to be more likely to take the medicine by the end of the year?
Dr Shipra Arya: Yes, absolutely. That's what I tell my patients who come and see me, that this medication works on arterial plaques, and it stabilizes them. It's not just the same plaque that you have in your heart is the one you have in your leg. Maybe a little different, but to oversimplify, yes. This is not just a heart medication, and this is not just a cholesterol medication. This is a medication for your plaques, for your blockages. That's how I explain it to them, and I think the uptake would be more if we explain to them that, yes, this will help you keep your leg, stay ambulatory and stay at home and not end up in assisted living or nursing home.
Dr Josh Beckman: Carolyn, this is so much fun, especially when we get to talk to the people that do so much hard work to put stuff in circulation, so I just want to say thanks again to Shipra and her coauthors.
Dr Shipra Arya: Thank you so much, and thank you for giving us the opportunity. I think the comments from Circulation really made our paper better, so thank you for doing that.
Dr Carolyn Lam: I wish that we could just keep going on and on because I just know that Josh has even more great questions up his sleeve. See, Shipra, I told you, he's amazing. But, there you go. You're amazing, too. Your paper is amazing. Thank you so much for joining us today.
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 paper this week is an in-depth paper on the cardiovascular and metabolic heterogeneity of obesity, and we will have a discussion with the authors on the clinical challenges, implications for management, and much more coming right up after these summaries.
How does MRI quantification compare with standard Doppler echo approach to identify organic mitral regurgitation and predict adverse outcomes? Well, our first paper this week addresses this question, led by first and corresponding author, Dr. Penicka from the Cardiovascular Center OLV Clinic in Belgium. These authors studied 258 asymptomatic patients with preserved left ventricular ejection fraction and chronic moderate and severe organic mitral regurgitation by echo. All patients underwent MRI to quantify regurgitant volume of this organic mitral regurgitation by subtracting aortic flow volume from the total left ventricular stroke volume. Severe organic mitral regurgitation was defined as a regurgitant volume of greater or equal to 60 milliliters.
The authors found that mean echo-derived regurgitant volume was an average 17 milliliters larger than the MRI-derived regurgitant volume. Concordant grading of organic mitral regurgitation severity with both techniques was observed in 76% of individuals. In the remaining 24% of individuals with discordant findings between the two techniques, this was mainly observed in patients with late systolic, eccentric, or multiple jets.
The MRI-derived regurgitant volume showed the highest discriminative power among all the imaging parameters to predict all cause mortality or its combination with development of indication for mitral valve surgery. Thus, this study demonstrates that MRI-derived assessments of organic mitral regurgitation are clinically accurate to identify asymptomatic patients with severe organic mitral regurgitation and at first outcomes. This may be particularly so when the mitral regurgitation is late systolic, eccentric, or multiple in jets where misclassification may occur with echo-derived approach.
The next study is the first large population-based study to analyze the association between low-dose ionizing radiation from cardiac procedures and incident cancer in adults with congenital heart disease. First author Dr. Cohen, corresponding author Dr. Marelli from McGill University, studied the population from the Quebec Congenital Heart Disease Database and performed a nested case control study comparing cancer cases with controls matched on sex, congenital heart disease severity, birth year, and age. They found that the cumulative incidence of cancer in adults with congenital heart disease between the ages of 18 and 64 years was 15%. The cumulative low-dose ionizing radiation exposure from cardiac procedures was independently associated with incident cancer after adjusting for age, sex, year of birth, congenital heart disease severity and comorbidities.
Results were similar using either the number of procedures or estimates of the effective doses with a possible dose-related response relationship between the low-dose ionizing radiation exposure level and cancer risk. Thus, increasing exposure to low-dose ionizing radiation from cardiac imaging in adults with congenital heart disease raises concerns about life-long risk of malignancy. Confirmation of these findings by prospective studies is needed to reinforce policy recommendations for radiation surveillance in patients with congenital heart disease.
The next study characterizes the long-term dynamics of potassium in heart failure and its associated risk of mortality. First and corresponding author, Dr. Nunez from Hospital Clinic University of Valencia in Spain, evaluated the prognostic implications of long-term longitudinal monitoring and dynamics of serum potassium in a prospective and consecutive cohort of patients following a hospitalization for acute heart failure. In these patients, serum potassium was measured at every physician-patient encounter, including hospital admissions and ambulatory settings.
The authors found that on a continuous scale, the followup trajectory of serum potassium levels independently predicted mortality through a U-shaped association with higher risk at both ends of the distribution, and the same was true using potassium categories. Furthermore, dynamic changes in potassium were independently associated with substantial differences in mortality risk. Persistence of normal potassium levels was linked to a higher risk of death compared to patients who maintained or returned to normal values. Conversely, potassium normalization was independently associated with a lower mortality risk.
These findings support the need for close monitoring of serum potassium after an episode of acute decompensated heart failure and suggest that maintaining serum potassium levels within normal range may be considered a therapeutic target.
The next study gives us an example of how functional metabolomics can translate into metabolomics derived biomarkers of disease mechanisms. Co-first authors, Dr. Zhang, Wei, and Li; co-corresponding authors, Dr. Zhu, Li, and Qi from Nanjing, China, studied a cohort of 2324 patients who underwent coronary angiography from four independent centers. They used a combination of ultra-performance liquid chromatography and quadrupole time-of-flight mass spectrometry in the negative ion mode for untargeted analysis of metabolites in the plasma.
The authors identified a total of 36 differential metabolites related to coronary artery disease progression. In particular, N-Acetyl-neuraminic acid, a metabolic marker highly elevated during coronary artery disease progression, acted as a signaling molecule to trigger RhoA and Cdc42 dependent myocardial injury via activation of the Rho-RACK signaling pathway.
Silencing neuraminidase-1, which is the enzyme that regulates N-Acetyl-neuraminic acid generation, ameliorated myocardial injury in vitro and in vivo. Pharmacologic inhibition of neuraminidase by anti-influenza drugs protected cardiomyocytes and the heart from myocardial injury.
Thus, in summary, functional metabolomics identified a key role for N-Acetyl-neuraminic acid in acute myocardial injury, and targeting neuraminidase-1 may represent an unrecognized therapeutic intervention for coronary artery disease.
The final study addresses the controversy of whether high density lipoprotein, or HDL cholesterol, plays a causal role in cardioprotection. First and corresponding author, Dr. Jensen from Harvard T.H. Chan School of Public Health and colleagues, hypothesized that subspecies of HDL defined by apolipoprotein C3, a key regulator of lipoprotein metabolism, may contribute new information to prediction of cardiovascular risk.
They used immunoaffinity chromatography to measure the apo A1 concentrations of HDL that contained or lacked apolipoprotein C3, or apo C3, in two prospective studies of adults free of coronary heart disease, the Multiethnic Study of Atherosclerosis and the Danish Diet, Cancer and Health Study. They then conducted a meta-analysis that combined these results with the previously published findings from two cohort studies that used similar laboratory methodology to measure lipoproteins.
The authors identified a subspecies of HDL that contained apo C3. HDL that contained apo C3 comprised 5 to 6% of apo A1 or 10 to 15% of HDL cholesterol. In the four prospective studies, HDL containing apo C3 was associated with a greater risk of coronary heart disease, whereas HDL that lacked apo C3 was inversely associated with risk more strongly than the total HDL.
These findings support the hypothesis that apo C3 may mark a subfraction of HDL cholesterol that is associated with higher risk of coronary heart disease. These findings therefore provide novel insights for cardiovascular risk that extend beyond traditional plasma HDL cholesterol concentrations. And that brings us to a close for the summaries. Now for our feature discussion.
For today's featured discussion, we are talking about obesity, a universal issue, or is it? And when we talk about obesity, are we talking about one thing or many things? Today's in-depth review is just such a great paper. I highly recommend it to everyone. So pleased to be discussing it with Dr. Ian Neeland today from UT Southwestern Medical Center.
Ian, first of all, congratulations. A beautiful paper. I learned so much reading it, and I've got so many questions. You started off pointing out that we talk about obesity. We've always defined it by body mass index, but that may not be the ideal biomarker. I love the way you said that. So, tell us a bit more about the reason for this review.
Dr Ian Neeland: Obesity, like you said, we define it by body mass index, but body mass index is such a crude marker. It's great to use for the clinic. It's easy to implement, but it doesn't really tell us a lot of information about the person. And so you can just look at a third of the population in the US right now is thought to be obese. And if you take a third of the population, clearly not everyone has diabetes and heart disease.
So, obesity in and of itself, defined by the body mass index really is very heterogeneous, and it's not possible to use that alone to tell an individual if they're really at risk for disease. And so this review is really about getting deeper under the skin, no pun intended, to really get a sense of what it means to be obese, how the body fat plays a role in disease, and really getting to the different aspects of obesity and how we can understand it a little bit better.
Dr Carolyn Lam: Yeah. You know, Ian, you had me at hello if I could say when I read your paper because I'm from Asia, and here, the World Health Organization actually even suggests that we use lower body mass index cutoffs to define obesity, simply because there's a different relationship as well with cardiometabolic disease. So, so true, but before we get there, to maybe ethnic differences, I want to ask you something. I heard the term, obesity paradox, thrown around a lot, and sometimes I think we don't really know what we're talking about when we say obesity paradox.
I love the way, in your paper, you broke it down into four types. There are four paradoxes. Do you want to just clarify this for the audience? I think it's important.
Dr Ian Neeland: So, the obesity paradox, what we mean by that is we think that obesity causes disease and gives someone an increased risk for disease and mortality and death, but the obesity paradox means that some people who are obese we see actually have better outcomes than those who are not obese. And how to describe that paradox and why that exists is really the subject of lots and lots of research and discussion.
And so when we talk about the obesity paradox, really it's important to understand that most of the time we're talking about people who already have established disease. Let's say, for example, heart disease. So people with heart disease who are obese tend to have better outcomes than those who are not, and there are a few ways to understand that.
So people who have obesity with established disease who may have better outcomes; that's the classic obesity paradox. Then there's a paradox really about fitness and being fat and fit, and that concept that you can be fat, but if you're fit, if you're able to do exercise and you have good cardiorespiratory fitness, that you actually may be protected from disease as well. And then there's also the obesity paradox of basically the pre-obesity paradox, so that overweight, right, where you haven't yet met the threshold for obesity can also be protective in people who don't have disease. And so being a little bit plump may be protective for different diseases down the road. And then the final one is that the metabolically health obesity. When we say that, it means that the person who is obese by body mass index but doesn't really have any hypertension or diabetes or lipid abnormalities. So, that's the metabolically healthy obese person.
Those are the four types of individuals we see who may be obese but actually have better outcomes long term, and the question is why that exists. So there's a lot of thinking about it. Maybe it has to do with the fact that being normal weight nowadays, often we have older folks that are normal weight. Well, they tend to be more deconditioned. They may be frail. They may have undiagnosed disease like cancer. And that might be why those people are the worst. And there are the naysayers out there who think that it's all just about what we call confounding, so things we can't account for when we look at that. People who smoke tend to be lower weight, and obviously they have worse outcomes, and then also people who are older. So it's kind of a conundrum, this obesity paradox, but there's lots and lots of data out there coming out all the time that we keep seeing it again and again and again.
One of the areas in the paper that I wanted to address was this concept of obesity heterogeneity in the obesity paradox, meaning to say is it potentially where the body fat is that may be playing a role in which obese person gets disease, and which obese person may be protected from disease. So it could be that it's not how much fat you have but where that fat is that is really telling about what someone's risk is, and that might help to describe the obesity paradox and get us a little bit more understanding.
Dr Carolyn Lam: Yeah, now, I thought that bit was just so key and important. Not how much fat, not weight per se, but where that fat is. Do you want to elaborate on that a bit?
Dr Ian Neeland: Sure. For, I don't know, 50, 60 years we've had this concept of the apple and the pear. Right? Fat in the belly being the apple shape and fat in the pear being fat in the hips and buttocks and that being two different body types of body fat. So we have a lot of technology nowadays, and we can actually directly image body fat and where it is in the body. So we can do MRI, we can do CT, and we can actually see where the body fat is distributed and how much body fat in one area may be related to disease compared with another area.
So we've gone away from the apple and pear and really getting down to what we call body fat depots or adipose tissue depots where we deposit fat. And the area that we deposit fat that has the most risk for cardiometabolic diseases is this visceral adipose tissue or VAT. VAT is fat that's around the intra-abdominal organs, also near the kidneys, and you can't actually tell how much visceral fat someone has just by BMI or waist circumference or just looking at them. You really have to do this dedicated imaging to find out. And the reason for that is that in the belly there's two types of fat. There's the visceral fat, and there's the subcutaneous, which is the fat under the skin. Both those fat areas make up the belly fat, but they're very different. And part of the review is really going into depth about why these are different and how they're different.
They have completely different metabolic profiles, so if you would take blood, lipids, inflammatory markers, they would look completely different even in a single individual. And then if you look at the genetics of where the fat is, they're different. If you look at what these fat areas secrete, they're completely different. So it's really important to know where the fat is, and that's why I think this concept of sick fat versus healthy fat comes into play.
So, sick fat is fat that's usually in this visceral fat depot, and that is really the three central tenets we talk about are visceral fat or ectopic fat. Ectopic means fat where it doesn't belong. Then inflammation and cytokines, so secretion of abnormal factors in the blood from this fat, and then insulin resistance. So those are the three kind of tenets of this sick fat. So that's why we think that the sick fat plays a role in disease, and then there's a concept of less sick fat or healthy fat, which is maybe a sink. It actually buffers some of these cytokines and inflammation from causing disease in the body.
Dr Carolyn Lam: Yeah. I found that concept so fascinating, and just to bring it back to the obesity paradox. So, some larger people may enjoy better outcomes because they actually have a predisposition to put the fat subcutaneously perhaps, rather than viscerally. Would that be correct? You worded it so eloquently in your paper. There are some ethnicities or some genetic predispositions that could make one lose that inability to put it peripherally, and therefore it all goes viscerally, is what I got from it. And that's the stuff that puts people at risk.
Dr Ian Neeland: Yeah. We find that fat in the lower body, the hips and the buttocks, is actually in epidemiology, protective against heart disease, protective against cancer. And the problem is we don't know why some people put fat in the belly and some people put it in the hips and buttocks. There's very interesting twin-twin studies that show if someone has a predisposition for obesity, so twins may be both obese, but there is some difference in where they actually put the fat. So I think genetics certainly plays a role, but environment also plays a role. And environments, things like appropriate nutrition and physical activity can really alter genetics and help someone to put fat where it should be and prevent disease.
So this obesity paradox, this concept of putting fat where it should be, is really the next frontier for this type of research. How can we modulate it? How can we fix it?
Dr Carolyn Lam: Exactly, and I love the way you ended your review when you said, "Therefore, maybe in all our complaints and so on, saying that we want weight loss, we should actually be focusing on waist loss. You could redistribute the fat to healthy areas, not change your weight, and still become healthier." That was the concept, right?
Dr Ian Neeland: That's right. Yeah. It really is amazing, and it's been shown again and again that people can stay the same weight, but their body fat really is very plastic. It can change, and it's modifiable. And that really makes a difference with health outcomes. So whether we can do that with lifestyle changes, so there's some data to support that. There's also some data to support pharmacology, so medications may be able to move fat from one area to another. And then certainly surgery, which is now getting a lot of popularity for people who are really high risk for cardiometabolic disease. Bariatric surgery has been shown to decrease visceral fat significantly, and that may be one of the reasons why it works so well.
Dr Carolyn Lam: Exactly, Ian. Fascinating, fascinating. I tell you what. Could I just ask you to give us some take-home messages?
Dr Ian Neeland: Sure. So one take-home message I think is that we can move beyond the BMI, beyond the body mass index. Obesity is no longer just a number. It's really about the entire individual, biologic systems, what's going on, and there's just remarkable heterogeneity in the structure of obesity, where body fat is, the activity of body fat, the physiology of it, and also how it relates to diseases, either causing disease and potentially being protective for harmful outcomes.
I think it's also a key message to understand that there's sick fat and there is healthy fat and they're very different. And we can get to the bottom of those using specialized tools like imaging and special testing, but they're really very different, and not all body fat is created equal.
And then lastly, I think it's important to consider, like you mentioned earlier, that really public health and lifestyle going forward is going to be so important, and focusing on those areas that will have the biggest impact for people such as trying to promote waist loss, like you said, as opposed to weight loss. Really focusing and using our knowledge of body fat and obesity and how it's so different across individuals and populations, that it's really important to use that knowledge for our future goals and to have that mind when we recommend weight-modifying therapies for our patients.
It's really going to be a new frontier in weight. We're really moving beyond this concept of just check your weight and your height, and we can tell you what your risk is. No, it's really much more complex and complicated and much more interesting than that.
Dr Carolyn Lam: Oh, Ian, that's just so wonderful. I cannot help this last question. Who knows whether we'll put it in, but I just have to ask you. So how do you monitor your own status or your patients' status? Do you really get them DEXAs, all of them? Or PETs, FDGs? Or do you take your own weight?
Dr Ian Neeland: Yeah. I do. One thing I have noticed, I actually started an exercise and diet program for myself to improve my health about a year and a half ago. I took the research, and I said, "Okay, I'm really going to use this and apply this to my life." So, what's interesting is what I found and actually what other colleagues of mine in research are finding is that you can actually melt away visceral fat just with exercise alone, even if you don't actually go on a diet. And they've done studies like this where they do DEXA scans, and they give people high-intensity interval training. They don't give them a special diet. They just say maintain your current diet, and the visceral fat goes away.
It's really remarkable how lifestyle can be so important and make such a change. And you can see people who have diabetes who can cure their diabetes with a lifestyle program by really decreasing the visceral fat. Even if their weight doesn't change or only changes by a small amount, but their weight may change by, I don't know, five, 10 pounds, but their visceral fat may go away by 50%. And that really makes the difference.
It's obviously hard to monitor. We don't really have these tools clinically every day. Not everyone can do a DEXA and has the software to measure the visceral fat. Certainly could be coming in the future, but right now we should use the tools we do have and use the biomarkers we have and the clinical use, the waist circumference, triglycerides. These things are all surrogates for visceral fat but can be very useful to monitor for change. And it's not just about the scale. It's really about more than that with a person's metabolic status.
Dr Carolyn Lam: That is so helpful. Thank you so much, and I'm so glad you said that it was exercise, and you don't jump into a ice pool or something to try and convert the fat to brown fat or something. That's really, really encouraging to me. Thank you, Ian. This was so enjoyable. I'm sure all our listeners are thanking you as well.
Listeners, you've been listening to Circulation on the Run. Please tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, Associate Editor from the National Heart Centre and Duke National University of Singapore. How common is perioperative myocardial injury after non-cardiac surgery, and what is its significance? A very important question and a very important feature discussion coming right up after these summaries.
Our first original paper this week tells us that risk assessment using only non-laboratory based risk factors may be a useful alternative in the absence of informational lipids, in predicting adolescents at risk of developing pre-clinical atherosclerosis.
First and corresponding author, Dr. Koskinen from University of Turku Finland and colleagues, studied almost 2,900 participants, age 12-18 years, from four longitudinal cohort studies from the United States, Australia, and Finland, and followed these adolescents into adulthood. When carotid intima media thickness was measured, a mean followup of 23 years later. Non-laboratory based risk factors such as age, blood pressure, body mass index, and lipids measured in adolescence, independently predicted high carotid intima media thickness in young adulthood. The addition of lipid measurements to these traditional clinic based risk factor assessments provided a statistically significant but clinically modest improvement on adolescent prediction of high carotid intima media thickness in adulthood.
The next study demonstrates the feasibility of large scale aptamer multiplexing at a level that has not previously been reported and with sample proof that greatly exceeds other existing proteomic methods.
Now, like antibodies, DNA aptamers can be generated as affinity reagents for proteins. Emerging data suggests that they can be used to measure blood protein levels in clinical cohorts. However, the technology has, to date, remained in its infancy. In today's study, co-first authors, Dr. Jacob and Dr. Ngo, co-corresponding authors, Dr. Jennings and Gerszten, from Beth Israel Deaconess Medical Center in Boston, tested the scalability of a highly multiplexed expended proteomic technique that uses single stranded DNA aptamers to assay human proteins with a markedly expended platform containing approximately 5,000 aptamers targeting a far broader range of analytes than previously examined using this technology. They applied the platform to a cohort of individuals undergoing septal alcohol ablation for hypertrophic cardiomyopathy, using this as a human model of planned myocardial injury.
Now, in addition to confirming findings from prior studies, they identified nearly 150 additional putative markers of myocardial injury. Thus, these findings suggest that the expanded aptamer based proteomic platform may provide a unique opportunity for biomarker and pathway discovery following myocardial injury.
The next study addresses the potential long-term effects of low LDL cholesterol on neurocognitive impairment and decline. This has been a concern with pharmacologic PCSK9 inhibition. The first author, Dr. Mefford, corresponding author, Dr. Levitan from University of Alabama at Birmingham, investigated the association between PCSK9 loss of function variants and neurocognitive impairment and decline in the regards study.
In this general population sample of African American adults, they found no association between PCSK9 loss of function variants and neurocognitive impairment or longitudinal neurocognitive decline. There was also no association between lower LDL cholesterol levels and neurocognitive impairment or decline during follow-up.
The study, therefore, provides evidence in a contemporary population that PCSK9 loss of function variants and resulting lifelong exposure to low LDL cholesterol levels are not associated neurocognitive impairment or decline.
The final study explores long-term outcomes in patients with Type 2 myocardial infarction and injury. First and corresponding author, Dr. Chapman from University of Edinburgh and his colleagues identified more than 2,000 consecutive patients with elevated cardiac troponin I concentrations at a tertiary cardiac center. All diagnoses were adjudicated as per the universal definition of myocardial infarction. They found that at five years, all cause death rates were higher in those with type 2 myocardial infarction or injury compared with type 1.
Although the majority of excess deaths with type 2 myocardial infarction or injury were due to non-cardiovascular causes, the observed crude major at-risk cardiovascular events are MACE rates were similar between groups. Coronary heart disease wan an independent predictor of MACE in those with type 2 myocardial infarction or injury. Thus, despite an excess in non-cardiovascular death, patients with type 2 myocardial infarction or injury have a similar crude rate of major at-risk cardiovascular events to those with type 1 myocardial infarction. Identifying underlying coronary heart disease in this vulnerable population may help target therapies that could modify future risks.
That wraps it up for our summaries. Now, for our feature discussion.
So, I'm gonna go back to my first question on this podcast. How common is perioperative myocardial injury after non-cardiac surgery and what is its significance? Well, to give us an answer, I am delighted to have the first and corresponding author of today's feature paper, Dr. Christian Mueller from University of Basel in Switzerland, and we also have Dr. Torbjorn Omland, and he is associate editor form University of Oslo in Norway. Now, in case you're having deja vu, you are right. I have had these gentlemen on this podcast before and they were so successful, I had to call them back. So, welcome, welcome Torbjorn and Christian. Thank you for coming back again. Christian, congratulations on another beautiful paper. Could you tell us the highlights of what you did and what you found, but this time in particular tell us the novel aspects in view of the previously published vision study that was just published last year. Maybe you could just point out some of the differences.
Dr Christian Mueller: The topic is about an interdisciplinary topic and something, I think that is so important for us as cardiologists to get involved in with much more detail in the future. So, we are aware of acute myocardial infarction, sustained myocardial infarction event that we have studied extensively for decades and for which I think we have a fuller understanding of its cardiophysiology and we have excellent treatments. Completely novel entity is perioperative myocardial injury, so cardiomyocytes that die in the context of non-cardiac surgery. It's something that we as cardiologists should be really focused on because its likely the most important contributor to death in the perioperative period. So, the death rate among non-cardiac surgery is despite improvements in anesthesia and surgery remains remarkably high, between 1 and 4% within 30 days, depending on patient characteristics and surgical directives. And, it seems from our current understanding that the heart really plays a major role, rather high percentage of these deaths.
So, what is new in our study? Overall, our study took advantage of insight gained in the first phase of the vision study in that its has been documented that this perioperative myocardial injury fairly commonly occur without the patient or we as physicians getting aware of it. Either because the patient is still having anesthesia or because he may have symptoms that are atypical. So, we can only reliably detect this event if we screen an appropriate population, and that's what we have done. So, I think the criteria where a patient that's at higher risk of cardiovascular complication is defined at an age of 65 or higher or having pre-existing cardiovascular disease. So, this is the first major difference in which also much younger patients were enrolled. That's the most important differentiate as we had an open label screening. So, the screening was part of clinical routine and it was fine tuned to patients of whom we thought may have a reasonable high risk of developing this complication.
Dr Carolyn Lam: And, your main findings, because they were striking.
Dr Christian Mueller: As our most important finding, we were able to report the incidence of how many patients actually have a relevant amount of cardiomyocytes dying during the operation, and it was one out of seven patients entering our study. So, an incredible high incidence of this complication and that this complication not only is a very good end point that you shouldn't care too much was highlighted again and in full agreement, the suspicious is that if patients develop this complication of perioperative myocardial injury, their risk factor of whether they have any symptoms or atypical ischemic symptoms, and again, only a small minority had the risk of dying both within 30 days as well as in one year, was substantially increased.
Dr Carolyn Lam: Christian, before you go on, could you just please clarify, how did you define perioperative myocardial injury in this case, and was it the same as the definition used in Vision?
Dr Christian Mueller: The perioperative myocardial injury concept initially in Vision it was defined as detecting an elevated troponin just after a non-cardiac surgery, and why this was a perhaps an appropriate definition at the time when we were still using very poorly sensitive troponin assays inevitably is no longer appropriate nowadays because its obvious that particularly elderly patients may have chronic elevations and high sensitive troponin usually. Mild elevations due to a variety of disorders and [inaudible 00:11:51] important studies for us to understand that it is mild elevations troponin is quite common in patients with heart failure, with coronary artery disease or hypertensive heart disease, whatever. So, if we could detect or start detecting likely elevated troponin only after operation, we would never know whether this is something related to the operation itself or whether it's perhaps had already been around for months and weeks and represents the chronic condition. So, the novel concept is that we have to identify an acute rise in troponin, a dynamic genetics or just like that requested for the universal definition of myocardial infarction also of course [inaudible 00:12:32] So, we requested in this study, an increase from the concentration prior to surgery of at least 14 ng/l of high sensitivity cardiac troponin.
Dr Carolyn Lam: Right. Wow. What a great study. So systematic. So, all patients, basically had readings before and after surgery. You know, I've got so many questions, but I really, since you mentioned Torbjorn, I would really like to ask his perspective on what you think was the most striking parts of it and any questions you may have on Christian.
Dr Torbjorn Omland: First, I would like to say that this is a very impressive study with some very important results in a neglected area of medicine, really. So, there are several very strong points with this study, and I think that if we're able to, in such a large population, both have pre-operative and post-operative and was able to calculate the delta, and the importance of that was a very strong part of the study, because it showed that, as Christian alluded to, the baseline level did carry some information but there was also important additional information from the serial measurements. So, that's maybe one of the most important findings, I think.
Then, we addressed the question, how should we use these data? So, my question to Christian is actually, how will screening for exceptional myocardial injury affect clinical practice? Will it lead to clinical deficiency interventions that will improve outcome or will it just result in unnecessary testing?
Dr Christian Mueller: Very good important point, Torbjorn. I think you are absolutely right in indicating that I think we are just beginning to understand all of the part of physiology behind the event that we can now capture, detect really, rather simple and precisely with troponin screening. So, I think it's important that we highlight that the part of physiology behind this event differs from patient to patient. So, there are some patients who clearly have a type 1 myocardial infarction as the cause of myocardial injury. Very likely, they are the minority in this setting. Likely, the majority to have a kind of a type 2 myocardial infarction have a physiology with imbalance between supply and demand, and again, in these patients, of course, the management needs to be to identify the trigger and to correct the trigger as rapidly as possible. And it can be that detecting myocardial injury by the rise in troponin, is the first indication that there is a problem ongoing. Now the patient can have a physiological rearrangement might have already been aware to the physicians if it's a type 1 myocardial infarction, then obviously very likely the same therapy will be beneficial to this patient as we would apply in spontaneous myocardial infarction.
A very important, and I'm glad you alluded to that the different ways of, a rather wide variety of patient settings that are summarized of the term perioperative myocardial injury. And the consequences, likely will have to be individualized to really ensure that we do something good for the patient.
And if I may, I would like to ask you and Carolyn for your thoughts about the most appropriate wording. So, the current wording that we used, of course, has to be in any scientific precaution, a very conservative one, perioperative myocardial injury. And it's important that, in fact, there are some entities where likely injury is derived from the patients who have the injury related to serious sepsis or related to a stroke, or pulmonary embolism. However, it's very likely that the vast majority of patients, the term perioperative myocardial infarction would be appropriate. And, I think it's so important to be aware of the implication that this, perhaps, on first slight small difference might have. As long as we keep using the term "injury", cardiologists will not really feel the same need to be involved, the same need to really take care of this patient as compared to the use of "myocardial infarction". So, I think it's a balance between scientific accuracy, but also the need to create awareness.
So, I feel that if cautiously applied, we'll do more good if would more liberally use "myocardial infarction" within this context. So, would you agree with this perchance?
Dr Carolyn Lam: I think "injury" is at least better than what we used to say, "a leak'. You know, we used to say, "Oh, it's just a troponin leak". So, at least we're saying injury, recognizing that there is damage done. I just wanna highlight that in your paper, something that really struck me was that these patients with perioperative myocardial injury or infarction, indeed did as badly as those who did or did not fulfill myocardial infarction criteria. So, that kind of supports what you are suggesting. I did get that right, right? In your paper?
Dr Christian Mueller: Absolutely. I think for spontaneous myocardial infarctions, so clearly that the criteria defined in the universal definition are mandatory. There's nothing to discuss about, but we cannot criticize a patient who is undergoing general anesthesia that he doesn't feel chest pain, and therefore, we deny him the appropriate word of the events. I think is just important that we clearly highlight that it really can be the same event in the chest without symptoms. But, not due to anything else but because he is undergoing anesthesia.
Dr Carolyn Lam: Very good point. You know, I would really like, though, to go back to Torbjorn’s point, because I think that skeptics are gonna say we've created a problem that we don't know how to solve, or that we don't know how to treat. Do you know what I mean? So we're detecting all these things, because now we have all these assays. Patients are asymptomatic, and then we really don't know whether it's modifiable. We don't know what to do to improve outcome. So, could I ask both your expert thoughts on what the future should hold? What is next step? Because, I see a gap.
Dr Torbjorn Omland: Yes, that's of course, a key question. So, I think we need to be innovative and patient, because what we really need is clinical trials, perhaps and more clinical trials looking into different strategies. But, of course, that's also challenging because as Christian told us, the path of physiology among this group of patients with perioperative myocardial injury differs. So, what's going to be appropriate for one patient, may not be the appropriate therapy for the next patient. So, I think his suggestion of an individualized approach is the best thing we can say at this moment, while we are awaiting data from future clinical trials.
Dr Christian Mueller: I fully agree with Torbjorn [inaudible 00:19:53] what you said, you will criticize some people will argue to that it's irrelevant. Why do you measure this and you don't want to hear it? You don't want to see it. But, I think it's important to remember the starting point for us as cardiologists is to get involved is death. If death is within 30 days after non-cardiac surgery in a patient who was fit, relatively fit otherwise, who underwent a surgery that was not a very high risk surgery from which he would expect a certain percentage of patients to die. So, that's the starting point. Again, of course perioperative myocardial infarction is not the only contributor to perioperative death. But, it seems, in addition to severe sepsis, to be the second commonest and most important. So, I think it's really, really important to first, as a really as a first important thing to increase the awareness of this problem and to encourage our colleagues to start bringing their research efforts, so that we get smarter in identifying the underlying part of physiology in these infarcts or injuries.
Because, only once we understand, or have a reasonable understanding what is the mechanism, we will be smart enough to select the most important priority for any intervention study.
Dr Carolyn Lam: Wow. What a wonderful note to end this podcast on. Words of wisdom, as always from both of you, Christian and Torjorn.
See, listeners. Didn't I tell you this was gonna be a great podcast? Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, Associate Editor from the National Heart Centre and Duke National University of Singapore.
Have you ever wondered, which is better for heart health, low calorie vegetarian or a Mediterranean diet? Well, this week's feature paper provides some answers with a very intriguing discussion coming right up after these summaries.
The first original paper this week suggests that human fat pools are not the same and in fact are highly diverse in their response to lifestyle interventions during weight reduction first author Dr. Gepner, co-corresponding authors Dr. Shai from Israel and Dr. Stampfer from Boston aim to assess whether distinct lifestyle strategies could differentially affect specific body adipose depos. They performed at 18-month randomized control trial among 278 sedentary adults with abdominal obesity or dyslipidemia in an isolated work place with a monitored, provided lunch.
Participants were randomized to an isocaloric low fat or a Mediterranean low carbohydrate diet with or without added moderate physical activity. The overall primary outcome was body fat redistribution and the main specific endpoint was visceral adipose tissue. The authors further followed the dynamics of different fat depos by magnetic resonance imaging. They found that Mediterranean diet was superior to the low fat diet in mobilizing specific ectopic fat depos such as visceral, hepatic, cardiac and pancreatic fats. Exercise had an additional independent contribution to visceral fat loss. Long term persistent moderate weight loss inadequately reflected the significant beneficial effects of diet and exercise on the fat depos. Independent of weight loss, visceral and hepatic fat reduction was mainly associated with improved lipids profile whereas deep subcutaneous fat loss was associated with improved insulin resistance and superficial fat loss was neutral.
In other words, two distinct patterns were identified, a differentially responsive depo that was sensitive to the type of intervention, and those recites mostly directly related cardiometabolic health and a uniformly responsive depo, which corresponded only to weight loss per se irrespective of the intervention. Overall, these results suggest that more specific strategies for weight loss may be considered to treat distinct organ specific fat depos in the management of cardiometabolic risk.
Current guidelines recommend nonvitamin K antagonist oral anticoagulants or NOACs in patients with nonvalvular atrial fibrillation as these drugs have several benefits over the vitamin K antagonists but do these benefits remain when NOACs have to be combined with aspirin therapy? Well co-first authors Dr. Bennaghmouch and de Veer, corresponding author Dr. ten Berg and colleagues from the Netherlands provided a meta analysis comparing NOACs and Vitamin K antagonists in more than 21700 patients with atrial fibrillation who are treated with concomitant aspirin therapy. NOACs were found to be more effective in terms of stroke or systemic embolism reduction as well as vascular death reduction and as safe as vitamin K antagonist with respect to major bleeding. NOACs were in fact safer with respect to the reduction of intracranial hemorrhage. Thus, these authors found that NOACs were an effective and safe alternative as compared to vitamin K antagonists in atrial fibrillation patients treated with concomitant aspirin therapy.
The next study shows that an integrative approach using genomics and proteomics has the potential to identifying new biological pathways for biomarker discovery and pharmacologic targeting in early cardiovascular disease. Co-first authors Dr. Benson and Yang, co-corresponding authors Dr. Wang and Gerszten from Beth Israel Deaconess Medical Center in Boston had recently identified 156 proteins in the human plasma that were each associated with a net Framingham cardiovascular disease risk score using an aptamer-based proteomic platform in the Framingham Heart Study Offspring participants.
Now, in the current student these authors hypothesized that performing a genome-wide association study and exome array analyses on the levels of each these 156 proteins may identify genetic determinants of risk associated circulating factors and provide insights into early cardiovascular pathophysiology. Indeed, they discovered dozens of novel genetic variants that were each strongly associated with circulating levels of the Framingham Risk Score associated proteins. They highlighted numerous examples of how these novel gene locus protein associations provided new insights into cardiovascular disease risk pathophysiology including a novel pathway by which the gene phosphatase 1G modulated circulating levels of apolipoprotein E, a key regulator of cholesterol handling.
The final study suggests that bariatric surgery represents an effective strategy for reducing antihypertensive drugs in patients with obesity and hypertension. First and corresponding author Dr. Schiavon from Heart Hospital in Sao Paulo, studied 100 patients with obesity and hypertension who were randomized to gastric bypass or medical therapy alone. The patients randomized the gastric bypass were six times more likely to reduce by 30% or more the total number of antihypertensive medications while maintaining controlled blood pressure levels. In addition, 51% of the patients undergoing gastric bypass showed remission of hypertension. Now, the authors are quick to alert that given the morbidity of surgery these results do not imply that all patients with obesity and hypertension should be submitted for bariatric surgery. Rather, these results suggest that gastric bypass surgery represents one extra option to consider in achieving blood pressure control in these patients.
That wraps it up for our summaries now for our feature discussion.
So, which is better for heart health the vegetarian or the Mediterranean diet? Oh, what an awesome topic and to be able to discuss it from Asia to the United States to Italy, I'm so please to have the first and corresponding author of our feature paper this week Dr. Francesco Sofi from University of Florence in Italy and our dear associate editor Dr. Wendy Post from Johns Hopkins. Francesco, could you please start by telling us what inspired you to do this trial?
Dr Francesco Sofi: The aim of the study was to compare two of the most beneficial diets we know from the literature in relation to the occurrence of many chronic degenerative diseases so the Mediterranean diet we have a lot of studies showing that Mediterranean diet is beneficial for many different diseases as well as we have some studies for the beneficial effect of a lacto-ovo vegetarian diet but no studies are available comparing these two diets' dietary profiles. Our hypothesis was to compare in the same population different times the two diets, which were the similar calories, the same isocaloric but just different in terms of composition especially for meat and fish.
Dr Carolyn Lam: Tell us the bottom line. I'm holding my breath because I think I've said it before, I'm vegetarian. Half my household is Mediterranean diet so what did you find?
Dr Francesco Sofi: We found that in the same group of patients, which were a low risk population because a low risk population here in Italy they were already following a Mediterranean diet but if you control their calories and their composition in terms of the Mediterranean, which included all the different food groups and the lacto-ovo vegetarian diet so all the different groups except for meat and meat-based and fish we noticed that after three months, the lacto-ovo vegetarian diet already determined a reduction of total cholesterol and LDL cholesterol and Mediterranean diet already determined reduction of triglycerides and both were effective for reduction of body weight and fat mass.
We noticed with great interest that after three months, all the study population were quite good in [inaudible 00:09:45] with this diet. I mean they didn't have any kind of problems. This is the one of the most important thing and most of the population or many of the patients after the end of the study they started or continued to follow a vegetarian diet. It means that they accepted very well. There was no problem at all. Also, in feasibility and acceptability of this diet and in relation to this also they have a beneficial effect in some parameters such as also oxidative stress parameters and the inflammatory parameters.
Dr Carolyn Lam: Right, so if I could summarize maybe crudely so the vegetarian diet, very effective for LDL, the Mediterranean very effective for triglycerides. I know that's a simplification but Wendy, I'd like to know do you think this is the dawn of maybe a more, "Oh, here we go again individualized diet planning"?
Dr Wendy Post: I think that this study is really important because there really have been few randomized trials about the vegetarian diet and we've learned a lot of the potential beneficial effects of a Mediterranean diet. I think what was really interesting about this study is seeing that they were both equally effective as a low calorie Mediterranean diet or vegetarian diet at reducing body weight, which is most often the biggest challenge for our patients who are either at risk for cardiovascular disease like these patients potentially were or who have cardiovascular disease.
I think the vegetarian diet is potentially an excellent option for some of our patients but it really is an individual choice and I have trouble getting some patients to just give up the red meat let alone any kind of animal meat. I think it really is potentially an individual choice and those who are interested in becoming vegetarian for either health reasons or other reasons these are additional data to suggest potential beneficial effects more to the Mediterranean diet.
Dr Francesco Sofi: I think one of the most important things to know from this study is that we have now two options. We need to individualize the diets to patients but if a person wants to follow a vegetarian diet for different reasons including also healthy reasons, we can say that it's beneficial. He or she can follow this diet without no problems so without having any health problems as well as if a person wants to follow also a Mediterranean diet, which included meat and fish with a regular and moderate consumption during the week.
Dr Wendy Post: Right but this is just a three month trial with intermediate outcomes so I'm not sure we can necessarily make definitive statements that this is potentially not leading to any adverse effects or some of the other statements that you made. I think we could just make the statements better relative to the outcomes that were seen here related to weight loss and traditional cardiovascular risk factors. Whereas, we have had long term clinical trials of the Mediterranean diet suggesting reduction in risk for events so I think this is definitely supportive of the vegetarian diet but I think we can't say that more studies aren't needed to potentially look at longer term outcomes and more definitive events as opposed to intermediate outcomes that this is a great first start and is really helpful in trying to understand some of the potential differences between the vegetarian diet and the Mediterranean diet.
Dr Francesco Sofi: Of course, I completely agree on that. We need more studies and larger studies and longer duration to establish some things but it was just a pilot study but the good thing is the first comparing two beneficial diets. In the literatures now, most of the studies were investigated either already a vegetarian person or vegetarian diet versus a westernized diet so probably there were some biases.
Dr Carolyn Lam: Indeed, I want to just echo in these words. Congratulations, Francesco. Beautifully done, very elegant, controlled in terms of caloric intact and I like that message that it's not saying that one is bad and the other is good. It's saying, "They're different but they both resulted in weight loss". I love that comment about getting a bigger study. I want to do it right here in Asia because the diets are just so different here and I'm just wondering how about in the US? Wendy, your perspective? How adoptable are these results?
Dr Wendy Post: Well, again I think it's a personal choice and if somebody is willing to become vegetarian then that's potentially wonderful especially if they have high LDL cholesterol and are trying to lose weight but we have to be careful about with the vegetarian diet is the carbohydrate intake, which might affect triglycerides. It might be an individualized approach based on the patient's individual risk factor profile and they're preferences but this is really impressive data suggesting that the vegetarian diet is very similar to the Mediterranean diet in many aspects especially as it relates to weight loss, which is really important.
Dr Carolyn Lam: You've hit the nail on the head. Let's remember that this is a low calorie vegetarian diet. I think that's the issue. Sometimes when I say vegetarian diet to some communities here in Asia that is actually a lot of calories and a lot of starch, which is not what we're talking about here.
Dr Wendy Post: Right, a low calorie diet so that's the key. That's the hard part isn't it?
Dr Carolyn Lam: Yeah, sadly.
Dr Francesco Sofi: We should say that most diets are similar background I mean in the backbone is similar so a dietary profile full of fruit and vegetables, complex carbohydrates, fiber, so the different things are meat and fish but with you can see in a regular consumption also Mediterranean diet of course, especially Mediterranean diet is beneficial for cardiovascular profile.
Dr. Wendy Post: Yeah, if we could get our patients in the United States to follow either the vegetarian or the Mediterranean diet that would be fabulous because they are obviously eating too much in the way of sugar sweetened beverages and deserts and fast food so just trying to follow either of these diets would be especially beneficial if it was a low fat vegetarian or Mediterranean diet. I think we need to get all our patients to be eating more fruits and vegetables, which is a key component of both of these diets and what they share in common, which often can lead to beneficial effects with weight loss due to the increased fiber and satiety and the healthful benefits of high fruit and vegetable diet.
Dr Carolyn Lam: Thank you so much.
Audience, thanks also for joining us. You've been listening to Circulation on the Run. Don't forget to tune in again next week.
Dr Carolyn Lam: Welcome to Circulation on the Run. Your weekly podcast summary and backstage pass to the Journal and its editors. I'm Doctor Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore. This week's journal features an international external validation study of the 2014 ESE Guidelines on Sudden Cardiac Death Prevention in Hypertrophic Cardiomyopathy. A very exciting discussion coming right up after these summaries.
The first original paper this week suggests that proteomics, a tool of precision medicine may prove useful in improving the safety and efficiency of drug development. First author, Doctor Williams, Corresponding Author, Doctor Ganz, from the Zuckerberg San Francisco General Hospital retrospectively applied large scale proteomics to blood samples from Illuminate, the trial of Torcetrapib, a cholesterol estrotransfer protein inhibitor, which raised HDL and lowered LDL cholesterol. Recall that this trial was terminated due to increases in cardiovascular events and mortality.
In the current study, the authors found that plasma concentrations of 200 proteins changed significantly with Torcetrapib. Their pathway analysis revealed unexpected and widespread changes in immune and inflammatory functions, as well as changes in aldosterone function and glycemic control. A previously validated nine protein risk score was similar in the two treatment arms at baseline, but higher in participants with subsequent events. At three months, the absolute nine protein derived risk increased in the Torcetrapib plus Atorvastatin arm compared to the Atorvastatin only arm. Thus, this protein-based risk score predicted harm from Torcetrapib within just three months. A protein-based risk assessment embedded within a large proteomic survey may prove to be useful in the evaluation of therapies to prevent harm to patients. This is discussed in an accompanying editorial entitled "Harnessing the Power of Proteomics to Assess Drug Safety and Guide Clinical Trials" by Doctor Maggie Lam and Ying Ge.
The next study suggests that personalized monitoring of heart transplant outcomes may be achieved by profiling the genetic and phenotypic markers of the CD16-dependent natural killer cell activation pathway. First and corresponding author Dr. Paul from Vascular Research center in Marseilles in France and his colleagues collected blood samples from 103 patients undergoing routine coronary angiography for cardiac allograph vasculopathy diagnosis, a median of five years since their heart transplantation. They used a non-invasive natural killer cellular-humoral activation test to evaluate the association between genetic and phenotypic markers of the CD16 dependent natural killer cell activation pathway. They showed that the Fc-gamma receptor IIIAVV polymorphic variant, which encodes the highly responsive CD16-Fc receptor, was an independent baseline predictor of cardiac allograph vasculopathy, and may be useful for stratifying patients at higher risk of rejection. The implications of these findings also include the fact that individualized natural killer cell targeted therapies may limit vascular damage in responsive patients.
The next study suggests that estimation of polygenic atrial fibrillation risk is feasible, and together with clinical risk factor burden, can explain lifetime risk of atrial fibrillation. Co-first authors Dr. Weng and Preis, corresponding author Dr. Lubitz from Massachusetts General Hospital, and colleagues estimated the lifetime risk of atrial fibrillation in individuals from the community-based Framingham Heart Study. Polygenic risk for atrial fibrillation was derived using a score of approximately 1000 atrial fibrillation-associated SNPs. Clinical risk factor burden was calculated for each individual using a validated risk score for incident atrial fibrillation comprised of height, weight, systolic and diastolic blood pressure, current smoking, anti-hypertensive medication use, diabetes, history of myocardial infarction, and history of heart failure.
They found that the lifetime risk of atrial fibrillation after age 55 years was 37 percent was substantially influenced by both polygenic and clinical risk factor burden. Among individuals free of atrial fibrillation at the age of 55 years, those in the low polygenic and clinical risk tertiles, had a lifetime risk of 22 percent, whereas those in the high risk tertiles had a risk of 48 percent. Atrial fibrillation developed at an older age among individuals with a favorable clinical risk profile regardless of genetic predisposition. Nevertheless, the lifetime risk of atrial fibrillation in individuals with high genetic predisposition was substantial, even when the clinical risk factor burden was low. Thus, individualized projections of lifetime risk of atrial fibrillation may be refined by accounting for both genetic predisposition and clinical risk factor burden.
The final study tells us that in contrast to previous perceptions, Takotsubo cardiomyopathy has long-lasting clinical consequences. First and corresponding author Dr. Skally from University of Aberdeen in the UK and their colleagues did an observational case controlled study of 37 patients with prior Takotsubo cardiomyopathy and 37 age, sex, and co-morbidity matched controls. Although Takotsubo cardiomyopathy occurred 20 months before the study, the majority of patients had persisting symptoms compatible with heart failure and cardiac limitation on exercise testing. Despite a normal left ventricular ejection fraction in serum biomarkers, patients with prior Takotsubo cardiomyopathy had impaired cardiac deformation indices on echo cardiography, increased native T1 mapping values on cardio magnetic residence imaging and impaired cardiac energetic status on p31 spectroscopy. Taken together, these findings demonstrate that after Takotsubo cardiomyopathy, patients appear to develop a persistent long-term heart failure phenotype.
Well that wraps it up for our summaries. Now for our featured discussion.
Sudden cardiac death prevention and hypertrophic cardiomyopathy. Always such an important topic. I'm so pleased to have with us the author from our featured paper this week, Dr. Perry Elliot from University College London, nd our associate editor, Dr. Mark Link from UT Southwestern who also wrote a beautiful accompanying editorial with Tera Lynn Ho. So welcome both of you. Perry, I think to set us up, I'd really love if you could tell us a little bit more about the 2014 ESE guidelines for sudden cardiac death prevention and hypertrophic cardiomyopathy. And particularly pointing out how they may differ from the 2011 ACC AHA guidelines please.
Dr Perry Elliot: So, the 2014 guideline on sudden death prevention HCM, the aim of that guideline was to try to quantify the risk of sudden cardiac death. As you pointed out, sudden death is a significant complication of hypertrophic cardiomyopathy and one which we all as clinicians spend a lot of time trying to determine. If we look back over at, I don't know, a period of twenty, thirty years the approach we've developed is based upon the recognition of a number of clinical features of the disease that we know associate with a higher risk of sudden death. So things such as, you know, unexplained syncope or severity of hypertrophy. And it was that model of sort of taking those so called major risk factors which form the basis of the 2011 US guidelines and the essential model was the more of those things you have, the greater is your risk, and I suppose the higher indication for an ICD.
One of the problems with that approach was that it's not quantitative so you know, you could say, "Okay. Well I think you're at higher risk, but I can't say how much that risk is." And another problem with that way of doing things is when you start to think about some of the individual risk factors, it doesn't make a great deal of sense clinically.
And I suppose a good example of that is wall thickness. You know we have this magical number of 30 millimeters, above which we say you're at risk, but of course are we really saying that if your wall thickness is 29 millimeters you're at low risk? We know it doesn't really work that way in biology. So when we drew up the 2014 guideline we wanted to say, "Okay let's develop a model in exactly the same way that we do with atrial fibrillation or primary prevention in coronary disease so that we can say to the patient sitting in front of us, 'Based on your clinical assessment we think you've got a one, five, ten percent risk of something bad happening to you in the next five years.'" And then we can use that information to inform our decision about ICD implantation.
The model itself is not so revolutionary. I mean, it uses a lot of the conventional risk factors such as wall thickness, such as non-sustained VT on Holter monitoring, but what it did introduce was the factor of age, because we know that the age of the patient certainly determines their risk. We brought in [inaudible 00:10:12] obstruction because we've now got reasonable evidence showing that if you've got a big gradient, that certainly modulates your risk. And also probably for the first time, I suppose, left atrial size, which was one of those missing things I think in previous assessments. You know, it's a fantastic surrogate for restrictive physiology and certainly when we added it to the model it improved the predictive power of that model.
So I suppose in summary what we've done is to produce a tool which allows you to estimate risk and then use that to help you decide on whether an individual needs a defibrillator in the clinic.
Dr Carolyn Lam: You know Perry I believe you led those guidelines and I just want to congratulate you as well as that was such a beautiful explanation of what was going on behind those. Yup, but the proof is in the pudding isn't it? But you're providing that proof in today's paper. Tell us about it. So it's an external validation, a large international multi-centers study to actually validate these 2014 guidelines.
Dr Perry Elliot: That's right. I mean, I think when we generate these kind of models it's really important to test those models in different settings. The original model was based upon a relatively small number of European centers and I think what this paper does is it brings insights into different geographies and different health care systems. So we have participating centers from North America from the Middle East from the Far East and the idea here is to get as diverse a population as we can and just see if the model performs in the same way. And you know in a study just short of 4000 people, I think that we've shown that the model does indeed seem to behave in the same way. In fact, the numbers were remarkably similar. You know the ability of this model to discriminate between high and low risk patients was almost exactly the same as in the original paper, which I think gives us a level of reassurance that this model, this tool that we've developed, can be used in different health care settings.
Dr Carolyn Lam: Mark. I really enjoyed your editorial. I love the way that you started out with a case that really shows why this is so important. And I also love that you discuss some other studies that tried to validate the 2014 ESE guidelines as well. Could you just give us some of your thoughts there.
Dr Mark Link: Yeah. I first want to congratulate Perry and his fellow authors for this paper. I think it was a very nice paper. I was a champion of this paper from the time it got sent into circulation. And, you know, the big change in the 2014 European guidelines compared to the American guidelines is really the linear risk of age, wall thickness, and I'll put tract gradient. And as Perry says, I agree, it's not a simple you have it or you don't, it's a linear risk and I applaud them for including that in their risk factor stratifier. And if you look at the current paper, I mean it was very good at picking out high risk patients. So if you have greater than a four percent, six percent risk over five years, you did. And so for picking out the high risk patients it was very good. And for picking out the medium risk patients, it didn't function as well. It was best for separating out the high risk and the low risk population.
And I will say, based on this paper, I've started using the European risk stratifier in my clinical practice. So I do want to applaud them, you know, for the risk stratifier tool and this paper. But I do want to say, and I'm sure Perry will agree, that we're not there yet. We need better tools, because not only in this data set but in other data sets, because more of these individuals reside in the low risk population, more of the sudden deaths are in that population. And we need better tools. And over time they will come. You know, they may be MRI tools. They may be scar tools. They may be other tools that we aren't even aware of that are coming on the horizon, but we do need better tools as we move forward to identify those at risk for sudden death in hypertrophic cardiomyopathy.
Dr Perry Elliot: Yeah. No. I agree. I mean I think what I would say is if you sort of take a step back and look at the overall perspective in this paper, despite the fact that, you know, we've got nearly 4000 people and they're followed in different health care settings, the overall sudden death rate in hypertrophic cardiomyopathy pretty low. You know, so that's good for patients 'cause I think it shows that at least in managed populations, the risk of sudden death which is real and we've got to assess it, but I think it's really important to get that message over to patients that for most people with HCM they're at low risk. It is of course the challenge because when you're dealing with rare events, it's really hard to predict them. And this model is far from perfect. I would argue it's probably the best we've got for the moment, but you know, it's not that bad. It's not that bad.
I mean agree with you absolutely Mark, 'cause you know, either end it performs pretty well. In the middle there it's not as predictive, although what it tends to do is overpredict, rather than underpredict. So you know, I think if you use this model in your every day practice just the greatest risk is that you'd end up putting in probably more ICDs then you really need to rather than missing a lot of patients. You know, we really want to prevent every sudden death if we possibly can, but that's always going to be really hard I think and I think the fight goes on. We got to look for new risk predictors. It may be that we can interchange some of these predictors. They might be easier to assess in some practices, but I'm not a born optimist, but I really think it's amazing just how well in such a complex heterogeneous disease that this relatively simple assessment works. You know?
Dr Mark Link: Going forward, what do you think the future of HCM [inaudible 00:15:47] stratification will include? We've got the risk stratifiers in your calculator ready. And more specifically where do you think gadolinium enhancement will play a role in the future? So MRI findings of scar or gadolinium enhancement.
Dr Perry Elliot: The base we have at the moment show that the more scar you have, the greater risk of sudden death. It sort of makes sense, doesn't it? It's part of that substrate for ventricular arrhythmia. My own reading of it just so far is that I'm not sure what it adds to the existing way of doing things. I mean I think this is true of any biomarker, you know. I've got a new biomarker, what does it tell me that I don't already know? And with scar, we know the greater amount of scar, it often tracks with wall thickness. You're likely to have a thicker heart, you're more likely to have non-sustained VT. But I'm openminded on that front. The beauty about this model, for me, is that it's a tool to into which you can plug other things and you know, if we can get big enough data sets and we can use gads and the amount of scar and put that into the model and if it improves the performance of the model that's great. Those studies are underway at the moment and I think we eagerly wait the results of those studies.
For me, one of the missing things is the genetics. This is a heterogeneous disease with quite a complex genetic architecture, and despite the fact that you know it's 20, 30 years now since we identified the first gene, we haven't really factored that in to our risk models and I think that for me is one of the big challenges and opportunities over the coming years is to put together really large international data sets so that we can answer once and for all whether your mutation determines your prognosis.
Dr Mark Link: Yeah. I agree with the genetics also I think getting more information on that. And it’s been 30 years it still is not helping us prognosticate the risk of sudden death, but it should. I mean it really should. And I do think hopefully we will find other tools also as time goes on because it really is imprecise and it's very difficult when you're sitting there in front of ... You know, I just had a 20 year old yesterday come in with his family and he's got a three centimeter septum and he's got 12 percent scar and he's saying, "Gee what would you do and what would you do if I were your son?" And it's easy when you're looking at it in the aggregate. It's much more difficult when you're sitting there one on one with a patient in front of you.
Dr Perry Elliot: Of course. Of course. And I think another factor I think which is changing the dynamic of that kind of discussion is the evolution of ICD technology. You know, I think when you're dealing with young people the fear is long-term complications with leads isn't it? And I think with the advent of the SICD I sense it's already tipping the balance into perhaps a slightly more liberal approach to ICD implantation exactly in the kind of scenario you've just described Mark, you know you've got guy who's 20. He's got a really severe hypertrophy. Well you know, if you and mess ICD you know your threshold for implantation might be a bit lower.
Dr Mark Link: Yeah and in fact, after a two hour discussion that's what we decided on is that subcu ICD was the right thing for him. And everyone's very happy with that choice.
Dr Perry Elliot: Yep. I think it also raises another thing which I often think about is that as medics we're also probably not good at considering what acceptable risk actually is. You know? We develop models in different settings and hyeprtrophic cardiomyopathy, coronary disease, heart failure, and actually if you go back and critically look at the thresholds that are used to put in defibrillators, the absolute risks vary enormously. So you know, here in [inaudible 00:19:02] we're talking about an approximate annual risk of sudden death of about one percent per annum is sufficient to put in an ICD, but in long-QT world it's quite a different threshold that's used and of course that's because there is no defined number. You know the number's we used in the ESE model of greater than six percent you should have an ICD, well yeah that's the consensus number, there's nothing magical about it. There's nothing biological about it. And I think we've probably had greater debates at what acceptable risks really are.
Dr Mark Link: And that's become a big shared decision now in the States and actually everywhere. It's become a big word because it sued to be that the physicians would decide on who gets an ICD and who doesn't. And it's no longer that way it's a discussion with the patient, with the family. How much risk are they willing to take, both with an ICD and without an ICD, because there are issues with ICD, even though I'm a big fan. There are issues and especially with transvenous ICDs, but also with subcutaneous ICDs.
Dr Perry Elliot: Absolutely. Absolutely.
Dr Mark Link: You know, it's a different world now than it was 15 20 years ago.
Dr Carolyn Lam: Perry and Mark, this has been one of the most wonderful conversations I've had on these podcasts. I just can't thank you enough. I'm sure all our listeners are thanking you too. You've been listening to Circulation on the Run. You must tune in again next week for more beautiful conversations.