Dr. Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, associate editor from the National Heart Center, and Duke National University of Singapore. Our featured paper this week confirms the clinical utility of a polygenic risk score of common variants of cardiovascular disease. More soon after this week’s summary of articles.
The first original article describes distinct cell-specific roles for NADPH oxidase, or Nox2, in blood pressure regulation. This paper from first author, Dr. Sag, corresponding author, Dr. Shah, colleagues from King's College London British Heart Foundation Center of Excellence in the United Kingdom. The authors used novel gene modified mouse models to show that Nox2 in myeloid cells modulates basal blood pressure whereas endothelial cell Nox2 is involved in angiotensin II-dependent hypertension. The finding that Nox2 in different cell types has distinct effects on blood pressure, suggest that different diseases conditions may alter blood pressure through effects on Nox2 in different cell types. For example, it is conceivable that the effects on myeloid cells on basal blood pressure may be enhanced in inflammatory settings, whereas endothelial cell Nox2 activation may be more relevant to renin-angiotensin system-dependent hypertension. The current results are therefore relevant to the design of novel therapeutic approaches for hypertension by targeting NADPH oxidases.
The next paper provides a new, more accurate atherosclerotic cardiovascular disease risk prediction tool in familial hypercholesterolemia that may increase the efficiency of care and use of newer lipid lowering therapies. Co-corresponding authors, Dr. Mata and Pérez de Isla, from Hospital Clinicals San Carlos in Madrid, Spain, use data from SAFEHEART, a multicenter, nationwide, long-term prospective cohort study of 2,404 adult patients with molecularly-defined familial hypercholesterolemia and who have followed up for a mean of 5.5 years. They developed a robust risk prediction equation for incident atherosclerotic cardiovascular disease based on the following independent predictors; age, male gender, history of previous atherosclerotic cardiovascular disease, high blood pressure, increased body mass index, active smoking, LDL cholesterol and LPA levels. The new SAFEHEART risk equation performed better with a Harrell C index of 0.81 compared to 0.78 for the modified Framingham's risk equation and 0.8 for the ACC/AHA Pooled Cohort risk Equations. The authors therefore concluded that the risk of incident atherosclerotic cardiovascular disease may be estimated in familiar hypercholesterolemia patients, using simple clinical predictors, and that these findings may improve re-stratification and could be utilized to guide therapy in patients with familiar hypercholesterolemia.
The next study tells us that late gadolinium enhancement cardiovascular magnetic residents identifies patients with dilated cardiomyopathy but without severe left ventricular systolic dysfunction, who are still at high risk of sudden cardiac death. In this study, by first author Dr. Halliday, corresponding author Dr. Pennell, from Royal Brompton Hospital in London, United Kingdom, the authors prospectively investigated the association between mid-wall late gadolinium enhancement and the primary composite outcome of sudden cardiac death or aborted sudden cardiac death, among 399 consecutive referrals with dilated cardiomyopathy and a left ventricular ejection fraction above 40% seen at their center between 2000 and 2011. These patients were followed for a median of 4.6 years. 17.8% of patients with late gadolinium enhancement reached the pre-specified end point, compared to only 2.3% without late gadolinium enhancement.
Furthermore, following adjustment, late gadolinium enhancement predicted the composite end point, with a hazards ratio of 9.3. Thus, patients with dilated cardiomyopathy and mid-wall late gadolinium enhancement, and mild or moderate reductions of left ventricular ejection fraction should still be recognized as having a high risk of sudden cardiac death. This is important because these patients are not currently offered ICDs for the primary prevention of sudden cardiac death, based on current guidelines. Due to the low competing risk of death from non-sudden causes, it is possible that these patients will benefit from ICD implantation, but randomized trials are now required. These issues are discussed in an accompanying editorial from Dr. Markman of Johns Hopkins University, and Dr. Nazarian, Hospital of University of Pennsylvania.
The next study enhances our understanding of the role of immunity in hypertension. Now, the innate antigen-presenting cells and adaptive immune T-cells have long been implicated in the development of hypertension, however, the T-lymphocytes subsets involved in the pathophysiology of hypertension remain unclear. A small subset of innate-like T-cells expressing the gamma-delta T-cell receptor, rather than the more commonly expressed alpha-beta T-cell receptor, could play a role, and these were the focus in today's paper by first author Dr. Caillon, corresponding author Dr. Schiffrin, and colleagues from Sir Mortimer B. Davis Jewish General Hospital, McGill University, Montreal, Canada. In experimental models, the authors showed than angiotensin-2 infusion increased gamma-delta T-cell numbers and activation in the spleen of wall tite mice, as well as in increased the systolic blood pressure, and decreased mesentric artery endothelial function in wild type mice, but not in mice devoid of gamma-delta T-cells, or in mice depleted of gamma-delta T-cells by depleting antibody injections.
Furthermore, angiotensin-2 induced T-cell activation in the spleen and peri-vascular adipose tissue was blunted in null mice. In humans, there was an association between systolic blood pressure and gamma-delta T-cells. In summary, this is the first in-vivo demonstration that gamma-delta T-cells, a subpopulation of T-cells, play a fundamental role in the development of hypertension and vascular damage. These results will help design novel treatments to limit the progression of hypertension and vascular damage.
The final paper describes a novel multi-modality strategy for cardiovascular risk assessment. Dr. de Lemos and colleagues from UT Southwestern Medical Center in Dallas, Texas, hypothesized that a strategy combining promising biomarkers across multiple different testing modalities would improve global and atherosclerotic cardiovascular disease risk assessments among individuals without known cardiovascular disease. These modalities included: left ventricular hypertrophy by electrocardiogram, coronary artery calcium, N-terminal pro B-type natriuretic peptide, high sensitivity cardiac troponin-T, and high sensitivity C-reactive protein.
Using data from 6,621 individuals of the multi-ethnic study of atherosclerosis, or MESA, as well as 2,202 individuals from the Dallas heart study, the authors evaluated the association of test results with the global composite cardiovascular disease outcome, and that would include cardiovascular death, myocardial infarction, stroke, coronary or periphery revascularization, incident heart failure or atrial fibrillation, as well as atherosclerotic cardiovascular disease outcomes, which included fatal or non-fatal myocardial infarction or stroke. Over more than 10 years of follow-up, the authors found that each test result was independently associated with the global composite cardiovascular disease events in MESA. When the 5 tests were added to a base model, the C statistic improved, that was significant integrated discrimination improvement, and net reclassification improvement, and the model was well-calibrated. Using a simple integer score counting the number of abnormal tests, they showed that global cardiovascular disease risk increased with increasing score in a graded fashion. These findings were replicated in the Dallas heart study, and were similar for the atherosclerotic cardiovascular disease outcome.
This study therefore supports the potential value of a multi-modality testing strategy in selected individuals, in whom additional risk stratification is desired, beyond measurement of traditional atherosclerosis risk factors. The authors do highlight that additional studies are needed to validate the present findings, determine the optimal approach to implementation, and address direct and indirect cost implications of the additional testing.
Well, that wraps it up for your summaries. Now for our feature discussion.
Our feature paper today tells us that a polygenic risk score identifies a group of individuals with a higher burden of atherosclerosis, and greater relative benefit from statin therapy in the primary prevention setting. But perhaps even more significant, is that it addresses the fact that even relatively small effect sizes of common snips gathered together in a genetic risk score may have clinical utility in the prediction of cardiovascular disease, and to discuss this I'm so pleased to have the first author, Dr. Pradeep Natarajan from Massachusetts General Hospital, and Dr. Anand Rohatgi, associate editor from UT Southwestern. Welcome, gentlemen.
Dr. Pradeep Natarajan: Thank you very much, Carolyn.
Dr. Anand Rohatgi: Thank you, Carolyn.
Dr. Carolyn Lam: Pradeep, could you start by telling us what you did? This was a tour de force, please.
Dr. Pradeep Natarajan: Yeah, thanks so much for the invitation and the enthusiasm. So, briefly, large-scale, genome-wide association studies have discovered genetic risk variants in the population that individually associate with coronary disease risk. Many others have shown that an aggregate of these genetic risk variants predisposes to an increased risk for coronary disease by about 60%. But we sought to, with this study, understand how primary preventive statins could influence that risk, and whether these insights could be helpful in refining statin eligibility. So, among the individual variants that had been associated with coronary disease, we developed a risk score. This encapsulated 57 individual genetic variants. This risk score is independent of traditional cardiovascular risk factors, and identified individuals with a greater burden of sub-clinical atherosclerosis, defined as coronary artery calcium and carotid plaque, and two observational cohorts in individuals with a greater absolute and relative benefit from statin therapy from a subgroup analysis within the WOSCOPS clinical trial.
What we were surprised by is that the conventional wisdom, that all previously described subgroups within statin trials had the same relative benefit, and statins per unit of alveol cholesterol lowering. So, about 20 to 25% lowering of risk per 40mg per deciliter of alveol cholesterol. So we clinically identify individuals who just start out at high absolute risk, assume that the relative benefit will be the same across everyone, and optimize the number needed to treat simply by just finding individuals at high risk. But, here we didn't see the expected 20 to 25% lowering in the high genetic risk group, we saw actually a 44% relative risk reduction for the same lowering of alveol cholesterol. And we have now observed that across three different clinical trials, and these individuals are at high baseline risk, so this translates into an even more optimized number needed to treat, and really the opportunity to identify individuals earlier with an age independent biomarker.
Dr. Carolyn Lam: That's really cool, in fact, the number needed to treat in the high-risk score group was impressively low at 13.
Dr. Pradeep Natarajan: That's correct. Now, overall in the WOSCOPS trial, if you look at all individuals, it's about 38, so it is a high risk primary preventive group of men with, you know, substantial hyperlipidemia, but if you look at at least a relative difference between the two, going from 38 to 13, that's about a three-fold improvement of the number needed to treat.
Dr. Carolyn Lam: You know, what you said about it not correlating with exactly what you expected with the drop in LDL and so on, does that mean that this genetic risk score, that a lot of the snips are probably associated with LDL levels, but that a lot of them may be giving more information beyond LDL? Is that what it means?
Dr. Pradeep Natarajan: Yeah, you know, it's interesting. Most of the genetic variants that are associated with coronary disease actually do not seem to clearly influence traditional cardiovascular risk factors. The latest best estimate of that is about 39% of them associate with traditional cardiovascular risk factors, and then a subset with LDL cholesterol. So the aggregate score actually does not associate with traditional risk factors, and including with LDL cholesterol.
Dr. Carolyn Lam: Wow, and Anand, I'm sure we had so many discussions with the editors about the paper. Could you share some thoughts?
Dr. Anand Rohatgi: Yes, Carolyn. Circulation as a journal represents the best in cardiovascular science, and we're always interested in the highest-level articles related to atherosclerotic cardiovascular disease. So, when we received this manuscript from Pradeep and Sekar’s group, really leaders in the field, we were really excited, and as we went through the review process we got even more excited because it, as you said, Carolyn, it really was a tour de force, it was a high-quality article and it combined multiple things, and that's what we're really interested in seeing at Circulation, is combining several aspects, in this case genetics, sub-clinical atherosclerotic imaging, and also treatment effect.
And, you know, it's interesting because several recent manuscripts looking at genetic risk scores, they were associated with coronary disease but it wasn't clear that they were improving what we call risk prediction performance indices, at least enough to meet the bar of incorporating them into guideline-type recommendations. So I think the field wasn't sure how to move forwards with this type of information, but now I think this study really demonstrates that this type of risk score, this genetic risk score, really can inform treatment decisions in a big way. And so we were really excited to talk about that and then see it move forward.
Dr. Carolyn Lam: So a question for both of you now. Can these data be extrapolated to other cohorts of patients? I mean, WOSCOPS was predominantly white, and all were males, right? So, Pradeep, would you like to take that first?
Dr. Pradeep Natarajan: That's an excellent observation, and I think ... A clear limitation in the field, but an outstanding question that I think can be addressed going forwards. So, the main challenge is that the epidemiological cohorts that were used for genetic analysis largely have been of European ancestry, and we know that genetic background and a variety of non-genetic factors influence cardiovascular disease risk, so in genetic analysis of European individuals the influencers of coronary disease risk may not influence cardiovascular disease the same in non-European ethnicities. And, you know, we've done some work of this specifically in African-Americans, and there are some differences. You know, African-Americans are largely mixed of both African and European ancestry, some of that seems to also influence how you interpret the cardiovascular genetic risk score.
Ideally you would have a risk score that is not influenced by the genetic background, and so the next step going forward are one to look to see how well this risk score predicts in non-European ancestry, because, obviously, not as much statin clinical trial information in non-European cohorts, but I think looking at the treatment effect in non-Europeans will be important. And then, you know, the third step is we and others are participating in several now large ongoing efforts to really define what the genetic influences are in non-European ancestries, and I think that will be a very important next step that's really critical before the clinical implementation.
Dr. Carolyn Lam: Yeah, talking to you from Asia, that's music to my ears, obviously. Anand, did you have any questions for Pradeep or anything else to add about the paper?
Dr. Anand Rohatgi: Yeah, I wanted to add one or two comments. One thing that this study demonstrates is that the genetic risk scores, whether they relate to traditional risk factors or lipids, that doesn't necessarily translate to what it might mean in terms of treatment benefit, and so I think that concept is generalizable and now it needs to be tested in other ethnicities, other types of subgroups, but I think you can disentangle a relationship with risk factors and lipids to its treatment effect and this study really nicely shows that.
And I think just to take a step back, we know statins work in intermediate-risk patients, maybe even low-risk patients with the most recent studies, but at a public policy level, and just as a cognition, we really want to narrow the focus, it's something called precision medicine that the American Heart Association is promoting as a concept, and I think that this study really demonstrates that here we have now another tool that can reduce this number needed to treat, make this choice for statins more precise, maximizing the benefits and limiting cost. So, I think that concept is very generalizable, it needs to be tested now in multiple populations, like Pradeep said, and I guess one of the questions I had had for the authors is: how do we incorporate this finding that they saw with sub-clinical atherosclerosis, which we thought was very fascinating among the editors at Circulation, that now they're also linking with sub-clinical atherosclerosis, is that something that the investigators think needs to be pursued further? Would that be something that would be used clinically as well?
Dr. Pradeep Natarajan: I think there are lots of opportunities for this going forward, you know, in prior work we've done the genetic architecture for clinical coronary disease is actually very similar to sub-clinical coronary disease, and there are many influences for sub-clinical coronary disease, and clinical coronary-disease, that are both genetic and environmental, and the aggregate effect from the polygenic risk on sub-clinical atherosclerosis suggests that it's obviously not absolute and there are other factors that influence sub-clinical atherosclerosis.
Dr. Carolyn Lam: Well, listeners, you heard it right here. Thank you for joining us this week, tell all your friends about it, 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. In just a moment we'll take a deep dive into hemo-compatibility-related outcomes in the MOMENTUM 3 trial of a fully magnetically levitated pump in advanced heart failure. But first, here's your summary of this week's journal.
The first paper sheds light on the biological mechanisms underlying cardioprotective effects of the Mediterranean diet. First author, Dr. Wang, corresponding author Dr. Hu and colleagues of Harvard, TH Chan, School of Public Health in Boston, Massachusetts studied 980 participants from the PREDIMED Trial including 230 incident cases of cardiovascular disease and 787 randomly selected participants at baseline followed up for 7.4 years.
Participants were randomized to a Mediterranean diet supplemented with extra virgin olive oil, a Mediterranean diet supplemented with nuts, or a controlled diet. Plasma ceramide concentrations were measured and the primary outcome was a composition of non-fatal acute myocardial infarction, non-fatal stroke or cardiovascular death.
The authors found a novel positive association between baseline plasma ceramide levels and incident cardiovascular disease. In addition, the association between baseline ceramides and incident cardiovascular disease varied significantly by treatment groups where a Mediterranean dietary intervention appeared to mitigate the potential deleterious effects of elevated plasma ceramide concentrations on cardiovascular disease.
These findings, therefore, strengthen the evidence base for recommending the Mediterranean diet for cardiovascular disease prevention and suggest that plasma ceramides have the potential to serve as markers of future cardiovascular disease risk.
The next paper describes a novel therapeutic approach against hypertensive cardiac remodeling and provides the first evidence of the cardio protective effect of cardiofibroblast-specific activating transcription factor 3 or ATF3. In this study from first author Dr. Li, co-corresponding authors, Dr. Du from Beijing Anzhen Hospital in China, and Dr. Ma from Thomas Jefferson University in Philadelphia and colleagues, the authors used a discovery-driven unbiased approach to identify increased ATF3 expression in mirroring hypertensive hearts and the human hypertrophic heart, expressed primarily by cardiac fibroblast cells. ATF3 knockout markedly exaggerated the hypertensive ventricular remodeling, a state rescued by lentivirus mediated microRNA aided cardiac fibroblast selective ATF3 over-expression.
Conversely, cardiac fibroblast specific ATF3 over-expression significantly ameliorated ventricular remodeling and heart failure. The authors further identified MAP2K3 as a novel ATF3 target, and that p38 was the downstream molecule of MAP2K3, mediating the profibrotic hypertrophic effects in ATF3 knockout animals.
In summary, this study provides the first evidence that ATF3 up-regulation in cardiac fibroblasts in response to hypertensive stimuli, protects the heart by suppressing MAP2K3 expression, and subsequently p38 TGF-beta signaling. Thus, identifying molecules mimicking endogenous ligands or inhibiting microRNA that down-regulate ATF3 expression, may represent novel therapeutic approaches against hypertensive cardiac remodeling. These, and other issues, are discussed in an accompanying editorial by Dr. Jennifer Davis of University of Washington.
The next paper tells us that clinical frailty score may need to be part of the pre-operative assessment of patients undergoing transcatheter aortic valve replacement, or TAVR. First author, Dr. Shimura, corresponding author, Dr. Yamamoto and colleagues of Toyohashi Heart Center in Japan, utilized the optimized catheter valvular intervention or OCEAN Japanese Multicenter Registry of 1215 patients undergoing TAVR and found that clinical frailty score correlated with other markers of frailty, such as body mass index, albumin, gait speed and grip strength. Furthermore, the clinical frailty score was an independent predictive factor of increased late-cumulative mortality risk. Thus, in addition to reflecting the degree of frailty, the clinical implications of these findings are discussed in an accompanying editorial by Dr. Jonathan Afilalo from McGill University in Montreal.
In the final study, we learned that long-term anabolic androgenic steroid use may be associated with myocardial dysfunction and accelerated coronary atherosclerosis. Dr. Baggish and colleagues from Massachusetts General Hospital in Boston, used a cross-sectional cohort design of 140 experienced male weight lifters, age 34-54 years, comprising 86 men reporting at least two years of cumulative lifetime anabolic androgenic steroid use, and 54 non-using men. Compared to non-users, steroid users demonstrated relatively reduced left ventricular systolic function and diastolic function on transthoracic echocardiography. Furthermore, steroid users demonstrated higher coronary artery plaque volume on coronary CT angiography compared to non-users. In summary, this is the first large controlled study of its type to demonstrate that long-term anabolic androgenic steroid use is associated with both systolic and diastolic myocardial dysfunction, as well as coronary atherosclerosis. Thus, when clinicians encounter young or middle-aged men who exhibit evidence of unexplained left ventricular dysfunction or premature coronary artery disease, the possibility of cardiotoxicity due to long-term anabolic androgenic steroid use should be considered in the differential diagnosis.
Well, those were your summaries. Now, let's move on to our featured discussion.
For our featured discussion today, we are actually reviewing a secondary analysis of the MOMENTUM 3 Trial, which is a multicenter study of the mag lev technology in patients undergoing mechanical circulatory support, with the HeartMate 3. And to discuss today's findings I'm so pleased to have the corresponding author, Dr. Mandeep Mehra from Brigham and Women's Hospital in Boston, Massachusetts, as well as Dr. Biykem Bozkurt, Associate Editor from Houston, Texas.
Welcome Mandeep and Biykem.
Dr. Mandeep Mehra: Thank you. It's a pleasure to be with you all.
Dr. Biykem Bozkurt: Thank you.
Dr. Carolyn Lam: Let's start by getting a few definitions right, shall we, just for our audience. This specific article, and congratulations Mandeep, it's just so great, it speaks of hemo-compatibility-related outcomes. Could you start by telling us what that is, and maybe reminding us what the original MOMENTUM 3 short-term results showed.
Dr. Mandeep Mehra: Sure. As our listeners are aware, left ventricular assist devices have really transformed the management of refractory advanced heart failure, by the introduction of a form of flow, called continuous flow, in the devices, which tend to render patients, relatively low pulsatiles to non-pulsatile. Now what we've seen is that the interface between this very unnatural physiology from continuous flow in concert with the patient's biology tends to create a constellation of problems that we sort of refer to as hemo-compatibility-related adverse events.
For example, we have seen a very curious development of recurrent gastrointestinal bleeds that tend to occur in a manner similar to what was observed with critical aortic stenosis, the so-called Heyde's Syndrome. Similarly we see stroke-related problems and we also see evidence of thrombosis that can sometimes develop within the pump. So we refer to the conglomeration of these unique complications that arise from the abnormal interface between the device and the patient as hemo-compatibility-related adverse events.
Dr. Carolyn Lam: And this is a secondary analysis, a six-month secondary analysis, right? So could you give a little bit of background of why you would hypothesize that these events might be different with the HeartMate 3 versus 2? I mean, it's quite unique that we're going back to creating a pulse.
Dr. Mandeep Mehra: Yes. Let me fist define for our audience what the MOMENTUM 3 Trial was designed to initially do, and is still doing. MOMENTUM 3 is a randomized controlled trial of two devices: one, a conventionally available continuous flow device called the HeartMate 2, and the second device, the novel pump called the HeartMate 3. The HeartMate 3 is a pump that took two decades to engineer. And it took that long because it is very unique, based on the following principles.
First, it's a small profile, so the entire pump can be placed intrathoracically. Second is that the way in which it moves blood, its rotor, is fully magnetically levitated, which means that it has no friction when it rotates. The third is that despite its small profile, this device has wide blood flow gaps, meaning that as blood is moving in this centrifugal flow pump, it does not expose the blood elements to as much of sheer stress as one sees with other conventionally available devices. And then finally, what this device has uniquely is a intrinsic pulse, and what that means is that we program this device in a fixed program to actually ramp its speed up and ramp it down so that it creates an intrinsic pulse of about 30 beats per minute, which is engineering-wise designed to improve pump wash out; that's the intention.
So the MOMENTUM 3 Trial was constructed to really compare these two devices and we recently reported, on the primary end point of the six-month outcomes of this trial. And the trial primary end point was set at survival free of a disabling stroke, or the need for re-operation because of pump malfunction. And what we found was that this pump, the HeartMate 3, clearly met its non-inferiority end point, versus the HeartMate 2, but also demonstrated superiority on the primary end point at six months. We were certainly not expecting to see superiority at this early time point, but we were very fortunate to see that.
Now what is unique about this is that for the first time ever, we saw no cases of suspected or manifest established pump thrombosis, as a result of de novo pump thrombosis requiring re-operations with the HeartMate 3 device. And this is a frequency of about 10% that we normally observe with pumps. That is one in 10 pumps will clot off within about six months, and require re-operation. So we were very gratified to see this observation in the short-term data of the primary MOMENTUM 3 database.
Now as a result of that observation, Carolyn, we thought that the hard end points, as are typically adjudicated for the primary basis of these clinical trials, missed the entire constellation of hemo-compatibility-related outcomes because these are patients who develop both bleeding and clotting complications. And the net burden of hemo-compatibility is not entirely available for review, which is the basis of this important secondary analysis that was published in Circulation.
Dr. Carolyn Lam: What striking findings. So tell us the bottom line.
Dr. Mandeep Mehra: What we found in the secondary analysis was evidence that the burden of hemo-compatibility-related adverse events is lower in patients with the HeartMate 3, compared to the HeartMate 2 device. And that was the basis of the bottom line that we found.
In particular, we knew that there were no episodes of de novo pump thrombosis with the HeartMate 3, but we also found that there was evidence of a reduction in non-disabling strokes with the HeartMate 3 device. So we now have evidence that thrombotic complications, minor strokes, as well as pump thrombosis, seem to be abrogated by this new pump.
What we should keep in mind, however, is that this is still early data from the ongoing MOMENTUM 3 Trial, and the trial is actually designed to enroll and observe over a thousand patients, over two years. And we are basically showing in this a very early look at six months of about 300 of these patients. And so that needs to be kept in mind. But we are extremely encouraged by these early trends suggesting that we may have started to break the issues related to the barriers of implementation of such therapy in the hemo-compatibility domain.
Dr. Carolyn Lam: Yeah, and as a heart failure doc, I can tell you that I share that excitement and I know that Biykem does too, as did the editors.
Biykem, tell us a little bit about what we talked about as editors about this paper.
Dr. Biykem Bozkurt: Indeed. Mandeep, the hemo-compatibility concept which is being addressed in this new publication is quite novel and is exciting, and addresses the continual spectrum of the pathology, ranging from the GI bleed, to the stroke spectrum. The question I have, in this study, the overall scores were not different in the absolute number that we saw as a score from the hemo-compatibility ranking.
Do you think we would continue to use this approach as a quantitative score, given the fact that there may be bidirectional impact from different devices on the different spectrum, especially with the recognition that HeartMate 3 seemed to be protective against the thrombotic, perhaps events, or should we use it more of a qualitative score card looking at which perhaps spectrum the device tends to be a little bit more risky or beneficial. So shall we color code this score and try to perhaps focus on the spectrum of thrombosis versus bleeding and then try to strategize?
Dr. Mandeep Mehra: Thank you for that very erudite question, Biykem. You hit right at the heart of the matter. So let me make a few comments about that. The first issue is that so far, the field has not had a clear definition of hemo-compatibility. Hemo-compatibility has been more of a engineering term. When someone said hemo-compatibility, they thought of biomaterials, rather than a clinical definition of hemo-compatibility. So for the first time, we have actually introduced the term hemo-compatibility into the lexicon of definition, managing patients with LVAD, so that's one important point.
The second important point is that we, until this day, until this analysis, have not had the ability to really provide people with a full picture of the entire burden of experience of hemo-compatibility-related complications that an individual patient experiences as they are on this device, because you know that patient's going to have a GI bleed, and then they may have a stroke, because we may change, dynamically we may change anticoagulation for instance if someone has one event then the other, and the traditional way in which studies are done, hey do not give you a clear picture into the burden of hemo-compatibility. So the most innovative thing about this clinical hemo-compatibility definition, is that we've not introduced a score that reflects the burden of disease, and we have also created tiers of severity of the burden of disease experience into three quantitative tiers that include various subsets which are hierarchal.
So for example, is one gastrointestinal bleeding the same as non-disabling stroke? Well, no. One gastrointestinal bleeding may be a milder form a hemo-compatibility-related problem. So our early look at this clearly shows that survival free of a hemo-compatibility-related event is clearly lower in the patients with a HeartMate 3. However, as you astutely pointed out, when you examine purely the burden of hemo-compatibility-related complications experienced by the survivors, one actually sees a trend in favor of the HeartMate 3, but not a statistically significant difference, largely because we have not yet abrogated problems related to bleeding complications on the side of the hemo-compatibility.
Why is that? Well, it's because we still treat all patients in both groups with the HeartMate 2 or the HeartMate 3 with the same intensity of anticoagulation. What this sort of data points out to us in the future, first of all, is that it allows us to compare apples to apples, as we are looking at different device platforms, that's number one. Second is it gives a much more robust look into the total patient experience. And third, it actually gives us insight into whether altering one component of the equation, so let's say there's a bleeder, if you actually react to that clinically, will you start to see problems on the clotting side.
Dr. Biykem Bozkurt: This is a very, very important study that addresses the whole spectrum of hemo-compatibility in a more comprehensive fashion, and also points out perhaps the differences that we see in overall others, centrifugal flow, left ventricular assists, support systems such as the Heartware HVAD study that showed increase in hemorrhagic stroke, especially hemorrhagic stroke in the first six months in the ENDURANCE Trial, whereas the HeartMate 3 has shown in the MOMENTUM 3 publication, as well as the Circulation secondary end point study demonstrates a reduction in disabling strokes and absence of any pump thrombosis.
So there are differences, despite both of the pumps are centrifugal, there are differences in the profile, and the spectrum of the risk and hemo-compatibility. And one other interesting finding from this study is that the predictors for hemo-compatibility outcomes are complementary to what has been known in the sense that lower antiplatelet and anticoagulation management strategies are associated with increased risk of hemo-compatibility adverse events.
And surprisingly, the control of blood pressure did not appear to correlate with the hemo-compatibility outcomes. So from that perspective, it differs from the ENDURANCE Trial where the uncontrolled blood pressure or hypertension was associated with hemorrhagic strokes, in the ENDURANCE Trial, whereas in the MOMENTUM 3, the blood pressure did not appear to correlate with the hemo-compatibility outcomes or pump thrombosis.
So these are very interesting findings and I think are complementary to the evolving field of the risk benefit ratios in patients with LVAD support. And from that perspective, we in Circulation felt that this will be a very valuable publication for our readership as well as for the whole heart failure and transplant community.
Dr. Carolyn Lam: Thank you, so much for joining us today, don't forget to tune in next week.
Dr. Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carlolyn Lam, associate editor from the National Heart Center, and Duke National University of Singapore. What's the link between DPP4 and aortic valve calcification? Well, to find out, keep listening because we'll be discussing this and an important new paper right after these summaries.
The first original paper in this issue tells us that high sensitivity Troponin I, may have a role in personalizing preventive strategies in patients with Type II Diabetes. Dr. Cavender and colleagues from University of North Carolina, Chapel Hill, sought to describe the relationship between changes in high sensitivity Troponin I and cardiovascular outcomes in the EXAMINE phase 3B trial, which was designed to evaluate the cardiovascular safety of alogliptin. The current analysis was restricted to patients, randomized 30 days or more after the qualifying acute coronary syndrome event, and high sensitivity Troponin I was measured using the Abbot Architect Assay at baseline and six months.
The authors found that high sensitivity Troponin I was detectable in the vast majority - 93% of patients with Type II Diabetes, stabilized within 30 days after acute coronary syndrome. One in six of these patients had high sensitivity Troponin I levels above the 99th percentile upper reference limit. High sensitivity Troponin I had a strong graded relationship with the incidence of subsequent major cardiovascular events.
Changes in high sensitivity Troponin I as small as two to six nanograms per liter over six months, were associated with a heightened risk of adverse outcomes. Particularly cardiovascular death and heart failure. Alogliptin neither increased nor decreased the risk of cardiovascular events in a high risk cohort of patients with elevated high sensitivity Troponin I levels. These findings therefore imply that serial measurements of high sensitivity Troponin may have a role in preventive strategies, either by intensifying or prolonging therapies in patients at high risk or reducing or shortening therapies in patients at low risk of cardiovascular events.
The next paper describes the effects of Pioglitazone on cardiac outcomes after ischemic stroke or transient ischemic attack in patients with insulin resistance without diabetes in the IRIS trial, which stands for Insulin Resistance Intervention after Stroke. As a reminder, the IRIS trial compared the effects of Pioglitazone with placebo on major cardiovascular events after stroke or transient ischemic attack, in patients without diabetes but who had evidence of insulin resistance. And it showed that Pioglitazone improved insulin resistance, prevented diabetes, improved CRP and reduced fatal and non-fatal stroke or myocardial infarction.
In the current paper, by Dr. Young and colleagues from Yale Cardiovascular Research Center in New Haven, Connecticut, the authors performed a secondary analysis of IRIS and examined the effect of Pioglitazone on acute coronary syndromes, mainly myocardial infarction or unstable angina. They found that Pioglitazone reduced the risk of these events by 29%, with benefit emerging after two years of treatment. Furthermore, Pioglitazone reduced the incidence of Type I myocardial infarction with a neutral effect on Type II myocardial infarction. In summary, among patients with insulin resistance without diabetes, Pioglitazone reduced the risk of acute coronary syndromes after a recent cerebrovascular event, and may serve as a useful secondary prevention therapy in addition to statins, aspirin, and other established treatments.
The next study tells us that immune complexes may be an important biomarker in the risk stratification of Antiphospholipid Syndrome. Now recall that Antiphospholipid Syndrome is characterized by recurrent thrombosis in patients with Antiphospholipid predictive antibodies. However, the predictive value of the presence of Antiphospholipid auto antibodies is low. And new markers are needed to identify carriers at higher risk.
In the current study by Dr. Serrano and colleagues from Madrid, Spain, the authors performed a historical cohort follow up study based on the Magnum 12 plus 12 cohort, that included all patients who had received a kidney transplant in their hospital in a 12 year period from 2000 to 2011. Sera used for the analysis were collected in the 24 hours before the kidney transplant surgery, and used to measure circulating immune complexes of immunoglobulin A bound to beta II glycoprotein I.
The authors then investigated the possible association of these immune complexes with thrombosis, graft thrombosis and graft loss in the six months following kidney transplant. They found that in patients with the immunoglobulin A isotope antiphospholipid antibodies, the presence of circulating immune complexes of immunoglobulin A bound to beta II glycoprotein I, pre transplant, was associated with acute thrombotic events. Patients positive for the immune complexes had a much higher risk of developing post transplant thrombotic events, and higher risk of graft thrombosis mediated graft loss. On the other hand, complex negative patients had the same thrombosis risk as the control population. These findings imply that treatment to prevent thrombosis should focus mainly on the immune complex positive patients in this setting.
The final paper addresses the issue that public reporting of PCI Outcomes may create disincentives for physicians to provide care for critically ill patients, particularly at institutions with worse clinical outcomes. In this study from first author, Dr. Waldo from the VA Eastern Colorado Health Care System in Denver, Colorado, corresponding author, Dr. Yeh from Beth Israel Deaconess Medical Center in Boston, Massachusetts, and colleagues. The authors used state reports to identify 31 out of 86 hospitals that were recognized as negative PCI outliers in two states: Massachusetts and New York, from 2002 to 2012.
They sought to evaluate the procedural management and in hospital outcomes of patients treated for acute myocardial infarction before and after a hospital had been publicly identified as the negative outlier. They found that outlier facilities were larger, treating more acute myocardial infarction patients, and performed more PCI's than non outlier hospital. The rates of percutaneous revascularization increased similarly at outlier and non outlier institutions after report of the outlier status. After outlier designation, the in hospital mortality declined at the outlier institutions to a greater extent than was observed at the non outlier facilities. Thus, public reporting of outlier status may prompt outlier facilities to improve case selection, and employ systems improvements that optimize patient care, and improve in hospital mortality among patients with myocardial infarctions.
We are going to have such a fun discussion in today's feature paper. Have you ever wondered what does dipeptidyl peptidase-4, or DPP4 have to do with aortic valve calcification? Well, you're about to learn, because in today's paper we actually learn that DPP4 inhibitors, which you might recognize from diabetes, you know drugs such as sitagliptin, could serve a potential therapeutic target in aortic valve disease. To tell us about it and discuss it, we have corresponding author, Dr. Jae-Kwan Song] from Asan Medical Center in Seoul, South Korea, as well as Dr. Thomas Eschenhagen, Associate Editor from University Hospital Hamburg Eppendorf in Germany. Welcome, gentlemen.
Dr. Jae-Kwan Song: Hi.
Dr. Thomas Eschenhagen: Hi.
Dr. Carolyn Lam: Fascinating paper. I have to congratulate you first and foremost, but please tell us, what inspired you to look at DPP4 in aortic valve disease.
Dr. Jae-Kwan Song: Yeah, actually as a clinician, I think there is two issues. One is the prevalence of calcific aortic valve disease is increasing rapidly in the developed and also developing countries. The second important issue is that we do not have effective medical treatment option. So I will say that the medical treatment of calcific aortic valve disease is a typical example of unmet clinical needs to serve this kind of troubled scientific issues, our team have focused on the reciprocal interaction between endothelial cells and interstitial cells. Because this potential mechanism was well reported by other investigators that the interaction between two cells are very critical for maintaining aortic valve tissues. So first we started with Enos knockout mouse, to go over what's going on in the aortic valve in the models. In the human tissues in patient with calcific aortic valve disease, we have found that DPP4 is specifically activated. That's the beginning of our study.
Dr. Carolyn Lam: Could you please explain to those of us who don't do basic science research everyday, I mean, your study involves tissues both from humans and mirroring models. Could you explain it very simply what you did and what you found?
Dr. Jae-Kwan Song: Yes, in the Enos Knockout mouse, we have found that those mouse showed very strong calcification process compared to the live animals. What is the mechanism of this enhanced calcification in this mouse? And we found that the loss of endothelial function is critical, and then we found that DPP4 is actively involved in the calcification process. The first test we have done is the isolation of developed interstitial cells. And then we focused on osteogenic transformation over this valvular interstitial cell both in the Enos Knockout mouse, and the human developing interstitial cells. So we have found that the endothelial dysfunction activates the DPP4 activity in these tissues, which resulted in the increase osteogenic transformation of developed interstitial cell. So that's the beginning of our observation.
Dr. Carolyn Lam: And could you describe what you did subsequently to prove the whole mechanism?
Dr. Jae-Kwan Song: As you know the DPP4 has many substrates including many peptides involved in glucose metabolism, so the hardest part of our study is what is the molecule target, or associated with DPP4 in the pathologic process of calcification in developing interstitial cells. We tested many different substrates known to the potential targets of DPP4, and we have found specifically insulin-like growth factor-1 (IGF-1) is the key proponent of all this process. With further study, we found that the DPP4 cleaves or inactivates or decrease IGF1 activity in the valvular interstitial cell, and in the normal status IGF1 is a very critical to protect osteoblastic transformation of valvular interstitial cell. We have found that the DP4 and IGF1 exercises key therapeutic target, and the key molecules involved in valvular calcification. As you know we do have a DP4 inhibitors, which were successfully clinically to reduce the diabetes control. So it's very easy to test the DP4 inhibitors in animal models. Both in the Enos Knockout mouse, and we also developed in the calcific aortic valve disease using some treatment, including Vitamin D and hypercholesterol and diet the in vivo experiment showed that [inaudible 00:13:58] inhibitors effectively prevented the development of calcification and prevented the development of calcification and prevented the developement of calcific aortic disease. This the main finding of our study.
Dr. Carolyn Lam: That is so fascinating, and really especially what you just said, that sitagliptin in this rabbit model prevented calcific aortic valve disease with the concurrent increase in plasma IGF1 levels in line with the DPP4 inhibition. That is just such a beautiful piece of work, congratulations. And congratulations Thomas on managing such a nice paper. Take us under the hood about the discussions that happened with the editors. Surely you recognized the translational impact. What do you think? Is it time to reposition DPP4 inhibitors?
Dr. Thomas Eschenhagen: We and the reviewers like the paper because first of all it describes a new, interesting biological mechanism. If we are done, and we like that it uses human samples, but also this treatment in two different animal models. This together, really makes it a strong paper, we've found perfectly suitable for Circulation. As you said Carolyn, the translation perspective is fascinating. Obviously it's very early days. There is no specific evidence yet from patients. But that could, in patients, take actually very very long. Even the big studies already been done with sitagliptin and other DPP4 inhibitors, that don't show a signal in this direction yet, but I would say that could still happen, and maybe in the long term, all of the cardiologists putting all this stuff in German it's call TAVS, in America it's called TAVR does not work anymore, obviously. That's just the speculation.
But it gives a very interesting signal, and this study certainly should stimulate research in humans and do some prospective studies in patients.
Dr. Carolyn Lam: Yes indeed. If I may ask, Jae-Kwan, do you have plans for further steps?
Dr. Jae-Kwan Song: Yeah, we are expecting some [inaudible 00:16:06]. The first process with proof of concept study as you know is DP4 inhibitors have been actually been used for the diabetic controls, so we may have a patient cohort who also underwent [inaudible 00:16:22] echocardiogram [inaudible 00:16:23] while without medication. The analysis of those later can be used for proof of concept study. But we are challenging issues that although many drugs are classified as a DP4 inhibitors, we should really focus on the tissue distribution on these drugs, specifically on the cardiac issues. It may be possible that the different drugs have a different tissue distribution even after all our medication. The second critical issue is what is the actual dose of these drugs to prevent calcific aortic valve disease. Usually these drugs are used for diabetes control. We may need different lab results of these drugs for different critical indications. So that's the two important issues to be solved.
Dr. Carolyn Lam: That's wonderfully put, and I couldn't agree more. Thomas, could we switch tracks a little bit. Because now that I have you online, and you're the first time joining us on the show too, tell us a little bit more about what it's like as an associate editor really looking at these pre clinical data, being able to parse out what you think has translational value, and especially for circulation. We have a very strong emphasis now on clinical translation. Share some of your thoughts there on how it's been for us.
Dr. Thomas Eschenhagen: It's been a great experience. I do have some experience with other journals as an associate editor, or being on an editorial board. But I have to say circulation is really quite unique. I think it's a very strong group of people. I'm amazed by the level of knowledge and also the level of engagement of the other editors and associate editors, in every single paper. What's also really rewarding is the overall quality of papers being submitted to circulation, it's really great. A lot of papers are not only presenting some beautiful, basic science, but also this translational perspective, that's actually what we are looking for. So very solid, exciting scientific work in cells, animals, but always some link, either some materials from humans or a good link to a translation perspective. That's the perfect paper for circulation and I have to say we get quite a bit of them, and it's sometimes even difficult to pick the ones we really like. But it's great, it's really been a lot of fun.
Dr. Carolyn Lam: This is actually one of the purposes of this podcast. It's hoping to share with our readers, with our listeners, what happens at these editor discussions because it's so interesting, I just wish everyone could listen to all the science and the clinical translation that we discuss. Thank you very much for sharing your thoughts today, both Thomas, and Jake Won, beautiful work. We're very proud to be publishing this work in circulation.
Thank you listeners for joining us this week. Don't forget, tell all your friends 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. In just a moment, we will be discussing the sources of sodium in the US diet, results that may surprise you, and that carry profound public health importance. But first, here's your summary of this week's issue.
The first original paper advances the field of cardiac tissue engineering by establishing a defined serum-free protocol to generate functional human myocardium from pluripotent stem cells. In this paper by first author, Dr. Tiburcy, corresponding author Dr. Zimmermann and colleagues from the University Medical Center Goettingen in Germany, the authors systematically investigated cell composition, matrix and media conditions to generate engineered human myocardium from embryonic and induced pluripotent stem cells and fiberglass, under serum-free conditions. The engineered human myocardium demonstrated important structural and functional properties of post-natal myocardium, including rod-shaped cardiomyocytes with M-bands, systolic twitch forces, a positive force-frequency response, inotropic responses to beta adrenergic stimulation, evidence of advanced molecular maturation by transcriptome profiling and the engineered human myocardium even responded to chronic cholinomimetic toxicity with contractile dysfunction, cardiomyocyte hypertrophy, cardiomyocyte death, and anti-pro BNP release, which are all classical hallmarks of heart failure.
Finally, the authors demonstrated scalability of engineered human myocardium according to anticipated clinical demands for cardiac repair. In summary, this paper provides proof of concept for a universally applicable technology for maturation and scalable production of engineered human myocardium, something that is termed a stride forward in an accompanying editorial by Doctors Yang and Murray, from University of Washington in Seattle.
The next paper describes a new frontier for interventional cardiology, the percutaneous therapy for tricuspid regurgitation. Here, Dr. Nickenig and colleagues, from University Hospital Bonn in Germany, recruited 64 consecutive patients deemed unsuitable for surgery who underwent mitroclip treatment for chronic, severe tricuspid regurgitation for compassionate use. Twenty-two patients were also concurrently treated with a mitroclip system for mitral regurgitation as a combined procedure. The degree of tricuspid regurgitation was severe or massive in 88% of patients before the procedure. The mitroclip device was successfully implanted in the tricuspid valve in 97% of cases.
After the procedure, tricuspid regurgitation was reduced by at least one grade in 91% of patients. 13% of patients with tricuspid regurgitation remained severe after the procedure. There were significant reductions in effective regurgitant orifice area, vena contracta width, and regurgitant volume. There were no intra-procedural deaths, cardiac tamponade, emergency surgeries, stroke, myocardial infarction or major vascular complications.
There were three in-hospital deaths. New York Heart Association class was significantly improved and six minute walk distance increased significantly. In summary, this study demonstrates that trans-catheter treatment of tricuspid regurgitation with the mitroclip system seems to be safe and feasible in this cohort of pre-selected patients.
The next paper describes the pooled safety analysis of evolocumab, a fully human monoclonal antibody to PSK-9. Dr. Toth of Johns Hopkins University School of Medicine and the PROFICIO investigators perform this pooled analysis from the PROFICIO program, which included over 6,000 patients from 12 Phase 2 and 3 trials, and the corresponding open-label extension trials, and they showed that treatment with evolocumab, up to one year, was not associated with discernible differences in adverse events, serious adverse events, or key laboratory assessments, compared to control or standard of care.
In addition, adverse events rates did not increase among patients attaining very low levels of LDL cholesterol, of less than 25 milligrams per deciliter, compared to patients attaining LDL cholesterol levels above 40 milligrams per deciliter. In summary, the present analysis confirms a favorable benefit risk profile for evolocumab treatment for up to one year.
Does aggressive blood pressure lowering prevent recurrent atrial fibrillation after catheter ablation? Well, this question is addressed in a randomized, open-label clinical trial known as the Substrate Modification With Aggressive Blood Pressure Control or SMAC-AF Trial. In this trial, Dr. Parkash of Halifax, Canada and colleagues, randomly assigned 184 patients with atrial fibrillation and a blood pressure of greater than 130 over 80 to aggressive blood pressure lowering, with a target of less than 120 over 80, or to standard blood pressure treatment, to a target of less 140 over 90, prior to their scheduled atrial fibrillation catheter ablation.
The primary outcome was symptomatic recurrence of atrial fibrillation, atrial tachycardia, or atrial flutter lasting greater than 30 seconds, determined 3 months beyond catheter ablation. The authors found no additional benefit to the addition of aggressive blood pressure lowering over a median of 3.5 months, over standard blood pressure therapy, in patients undergoing catheter ablation for atrial fibrillation to prevent recurring atrial arrhythmia.
In subgroup analysis, a signal of benefit was observed in groups whose blood pressure were lower at the point of entry into the study, and in those patients who were older. The duration of blood pressure lowering in the study did not result in reduction of recurrent atrial fibrillation after catheter ablation, however there was a higher rate of hypotension requiring medication adjustment in the aggressive blood pressure group.
Thus, this trial showed that neither aggressive blood pressure lowering compared to standard blood pressure lowering, nor the duration of aggressive blood pressure treatment reduced atrial arrhythmia occurrence after catheter ablation for atrial fibrillation, but resulted in more hypotension.
Well, that wraps it up for our summaries! Now, for our feature discussion ...
Our topic today is so universal and so important. It's about sodium intake and the sources of sodium, at least in the US, and I have with me two lovely ladies, the corresponding author of our paper, Dr. Lisa Harnack, from School of Public Health, University of Minnesota, and a regular on the show, shall I say, Dr. Wendy Post, Associate Editor from Johns Hopkins. Welcome, ladies!
Dr. Wendy Post: Thanks you, Carolyn! It's a pleasure to be here.
Dr. Lisa Harnack: Thanks, thanks.
Dr. Carolyn Lam: Lisa, let's dig right into your paper. Let's start by discussing that there was a prior paper that looked at sources of sodium in the US population. So please tell us, what inspired you to do your paper, and were you surprised by your findings?
Dr. Lisa Harnack: Right, well the previous study was over 25 years old, and it involved just 69 people from one geographic area, and, you know, it was informative, but it didn't tell us about America today, and how much sodium we're getting from different sources, and it didn't tell us much about a variety of ethnic groups ... we're a diverse country. So the CDC actually funded this study, and really they saw the need for it and laid out that this study needed to be done, as it was done, in three geographic areas, representing different ethnic groups.
Dr. Carolyn Lam: Tell us what you did.
Dr. Lisa Harnack: So, we recruited 450 people from 3 different areas, from Minneapolis/St. Paul metropolitan area ... Stanford was a partner in this study and they recruited people from that area of California, and then, finally, Birmingham, Alabama was a partner was a partner, and we got participants from there.
So the racial groups we had represented were white Americans, African Americans, Asian Americans and Hispanics.
Dr. Carolyn Lam: Yeah, I was really struck ... you had almost equal representation of women as well, didn't you?
Dr. Lisa Harnack: Right, so we made sure we had half of the participants were women, so we could really see how things stood with a variety of groups.
Dr. Carolyn Lam: That's excellent. What I was really impressed, as I'm sure, Wendy, you were, too, was the detail of the methodology. Could you tell us a little bit about that?
Dr. Wendy Post: Right, so we wanted to know all the sources of sodium. Part studies have tended to not ask about salt added to food at the table, and in home food preparation, because it's really hard to actually know ... you know, if you ask somebody, "Oh, did you add salt at the table? How much did you add?" They don't know. They just say, "Oh, well, I shook some salt on." So, we had people collect duplicate samples of the salt they added to food at the table and home food preparation. We gave them little baggies ... collection bags ... you know, after they added salt at the table, shake some into the baggy. So, we knew exactly how much because people do add salt in the home, so they have some control over how much sodium is in their diet. But the question is in how much under people's control in their home versus what's coming from the food supply.
Dr. Carolyn Lam: Right. And what I loved about the results is ... I think that it would challenge a lot of what people expect. Because when we talk about sodium restriction, everyone thinks, "Oh, it's the additional salt we add." And your study actually had surprising results. So, could you tell us?
Dr. Wendy Post: Yes, so it really was clear that the salt that people add at the table is just 5% of their total sodium intake, on average, across people in our study, and the salt added in home food preparation, like maybe the salt you add to your pasta when you're boiling it or to your eggs ... that was just 6%. So, 11% of the sodium in our study participants' diets was sort of that under-your-control in-the-home, and the rest was from other sources. So, the other things we looked at was, "Will water contribute some sodium?" So, we wanted to see how much comes from your home tap water. There's sodium that's just naturally occurring in food, like milk just naturally contains some sodium. So we wanted to look and see how much came from just naturally occurring in the food, and then the other question was how much is added by food manufacturers as part of making the food product, and that included the salt that might be added in making potato chips, as well as in restaurants ... the salt that might be added in making French fries or a pasta dish at a restaurant.
Dr. Carolyn Lam: And the biggest culprit?
Dr. Lisa Harnack: Yes, the biggest culprit was that latter source ... food added in processing.
Dr. Carolyn Lam: I thought that was amazing. Wendy, what do you think the public health message is? I mean, 70% almost of the salt's coming from processed foods from outside. What do we do? Stop eating it? What do we do?
Dr. Wendy Post: Right, so, on the editorial board for Circulation, we really liked this paper because of its very high impact for a public health message. So, as was stated, the sodium that we're getting in our diet is largely coming from processed foods and from foods we eat in a restaurant. So there are a number of ways that that can be modified and one is for our patients to read food labels and to make smart choices when they are shopping for processed foods in the supermarket.
But the other is for food manufacturers to decrease the amount of sodium in the products that they are making and there are voluntary suggestions by the FDA that food manufacturers reduce the sodium content of the food, and especially bread is incredibly high in sodium, and I suspect that most of our patients don't know that. So, if we were able to reduce the amount of sodium in the food supply by just a small fraction, it could have a large public health impact because we all eat.
So, it would affect everybody, and then I think the other really important public health message is about eating in restaurants and, of course, some people eat out more than others, and some people eat out in fast food restaurants, which, of course, are very high in sodium, but even in some of the nice restaurants that we go to, even expensive restaurants, the food is very heavily salted and I, for one, when I go out to eat, and sometimes don't like the taste of the food because it has so much salt in it, when I'm used to eating a low sodium diet.
So, there are a number of changes that occur on that level. One is for our patients to understand what foods tend to have a lot of sodium at a restaurant, but also for restaurants to notify their clientele of what foods are potentially lower in sodium and calories and generally provide the nutrient value so that we can make smart choices when we eat out.
Dr. Carolyn Lam: Yeah, indeed, congratulations, Lisa - what an important paper. Quick question, so that was the overall main message, but did you find any differences by different racial groups, by sex, by different socioeconomic status?
Dr. Lisa Harnack: We did find some differences. We found one difference was it looked like African Americans tend to add more salt at the table than some of the other groups, and, actually, Asians add less in our study. But still for all groups, that sodium added to food in processing was still the main source by a long shot, so, although there were some small differences by groups, it was clear that for all groups, the issue was the sodium added in processing.
Dr. Carolyn Lam: And for both Lisa and for Wendy, do you think these results are generalizable even beyond the US?
Dr. Wendy Post: I'd imagine that there would be quite a lot of variability, based on the habits of the various populations. So, here we're talking about eating outside the home, or food that's processed outside of the home, so there may be countries where most people are producing their own food and not necessarily buying processed foods or eating in restaurants, and then this would definitely be less applicable. And, of course, there are differences in foods that we eat based on our different ethnic groups.
Dr. Lisa Harnack: No, I would agree with what's just said. It really could be variable, but it does seem that a lot of countries are concerned about processed foods. Some countries implemented mandatory limits on the sodium in the foods in their food supply, so that would indicate to me that they know there's ... for some countries, there's serious concern about this source of sodium.
Dr. Carolyn Lam: Yeah, and I think this is really a wake-up message for us to examine where these sources of sodium ... I mean, even that simple message that it could be coming from bread, from drinking water, I think that would be surprising to a lot of us, even those of us practicing in medicine. Wendy, finally, you thought this was important enough to invite an editorial. I'd really like your thoughts there.
Dr. Wendy Post: You'll be able to read the editorial when it comes out in print, but the editorial also congratulates the authors on a really important paper, and the important public health messages, and, especially, compliments the authors on having a diverse group of participants, including ethnic minorities and men and women, and different geographic locations, so overall, it's a very important paper that I'm sure will have an important impact on the public health of our country and others.
Dr. Carolyn Lam: Listeners, you heard it right here. Remember, you're listening to Circulation on the Run. Please share this episode, and tune again next week!
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Doctor Carolyn Lam, associate editor for the National Heart Center and Duke National University of Singapore. Our feature paper today presents the first information on the impact of cardiovascular health in middle age and the burden of mobility in older age. This exciting data is from the Chicago Heart Association study. First, let me give you your summary of this week's journal.
The first study tells us that patients with long QT syndrome type II are at increased risk of hypoglycemia. First author, Doctor Hilton Cavallius, co-corresponding authors Doctor Tarakov and Hanson from University of Copenhagen, Denmark, noticed that loss of function mutations in HERG, which encodes the voltage gate at potassium channel 11.1, causes long QT syndrome II, but that the specific voltage gate at potassium channels are also present in pancreatic alpha and beta cells and intestinal L and K cells, which secrete glucagon, insulin, and the incretins, glucagon-like peptide one or GLP1, and glucose-dependent insulinotropic polypeptide, or GIP.
All these hormones are crucial for glucose regulation. The authors therefore hypothesize that patients with long QT syndrome II may have increased incretin and beta cell, but decreased alpha cell function and thus, lower glucose levels. To test this hypothesis, they measured secretion of these hormones and cardiac repolarization in response to a six-hour, 75 gram oral glucose tolerance test in 11 patients with long QT syndrome II with functional mutations in HERG with 22 matched healthy participants.
They found that following glucose ingestion, patients with long QT syndrome II displayed exaggerated incretin and endocrine pancreatic function with more than 50% increased levelsq of circulating insulin, GLP1 , and GIP and defective glucagon secretion, causing low plasma glucose levels and thus, increased risk of symptomatic reactive hypoglycemia following the glucose load.
Furthermore, in rats, pharmacological blockade of these voltage gate at potassium channel 11.1 with [inaudible 00:02:43] had similar effects and inhibition of HERG in beta and L cells increased insulin and GLP1 secretion up to 50%. Finally, glucose ingestion aggravated cardiac repolarization disturbances in patients with long QT syndrome II with a 122% greater increase in QT interval in these patients compared to controls. The take home message is that clinicians should be more aware of the risk of hypoglycemia with glucose ingestion in patients with long QT II syndrome and also recognize that this reactive hypoglycemia can further increase the risk of malignant arrhythmia in these patients.
The next paper is the first study to describe the risk of myocardial infarction after discontinuation of thienopyridine therapy in the DAPT study, or dual antiplatelet therapy study. As a reminder, in this trial, after PCI and 12 months of clopidogrel or prasugrel plus aspirin, eligible patients remained on aspirin and were randomized to continue thienopyridine versus placebo for 18 months. At 30 months, patients stopped the study drug and were observed for three months. In the current study by first author Doctor Schmidt, corresponding author Doctor Mauri, and colleagues from Brigham and Women's Hospital in Boston, Massachusetts. The authors looked at cumulative incidents of myocardial infarction assessed over three months after randomization and three months after study drug discontinuation. They found that discontinuing thienopyridine after either 12 or 30 months was associated with an early increase in myocardial infarction risk, mainly unrelated though to stent thrombosis. The magnitude of risk was highest in the early time frame and lower in patients not treated with the [inaudible 00:04:47] eluting stents.
The authors further compared pateints with DAPT scores above or below 2, and showed that both groups had lower rates of myocardial infarction with continued thienopyridine . Thus, while higher DAPT scores identify patients with a greater absolute ischemic benefit relative to bleeding with continued thienopyridine therapy, discontinuation at 12 months increases the myocardial infarction hazard regardless of DAPT score group.
The next paper describes the impact of depression treatment on one year mortality following acute myocardial infarction. Doctor [inaudible 00:05:28] and colleagues from the University of Missouri School of Medicine in Kansas City looked at the TRIUMPH study, which is an observational multicenter cohort study that enrolled more than 4000 patients with acute myocardial infarction between 2005 and 2008 from 24 US hospitals.
Patients were administered the patient health questionnaire 9 during the index myocardial infarction admission and depression was defined by a score of 10 or above. This was categorized as treated if there was a documentation of a discharged diagnosis, medication prescribed for depression, or referral for counseling, and is untreated if none of these three criteria were documented. Overall, 18.7% of patients met criteria for depression and 30.4% were treated. Compared without depression, patients with treated depression had one year mortality rates that were not different. However, patients with untreated depression had a higher one year mortality when compared to patients without depression. In summary, this study really shows that the association between depression following myocardial infarction and increased mortality differs by depression treatment status at the time of the index myocardial infarction. Patients with untreated depression have a 70 to 90% higher risk of dying at one year after the myocardial infarction than patients without depression or patients with treated depression. These findings should therefore encourage further research to examine the impact of depression recognition and treatment at the time of an acute myocardial infarction.
The final study provides insight into the paradox that folate deficiency is an independent risk factor for congenital heart disease, yet the maternal plasma folate level is paradoxically not a good diagnostic marker of this risk. In the current study by first author Doctor Wang, co corresponding authors Doctors Chow and Wang, from Fudan University, Shanghai, China. The authors examined six folate related polymorphisms in three independent case control groups comprising 1489 patients with congenital heart disease and 1745 healthy individuals from the Han Chinese population. They found that a specific fidgetin intronic 4 variant was associated with decreased circulating folate levels and increased protection against congenital heart disease. They further showed that increased fidgetin expression inhibited proteasomal degradation of reduced folate carrier 1 and dihydrofolate reductase, thus facilitating [inaudible 00:08:29] uptake and metabolism of folate. Their results therefore demonstrated that folate utilization, rather than the circulating folate levels, determined the preventive effects of folate against congenital heart disease. These findings provide new insights into the relationship of circulating folate levels with congenital heart disease and potentially other folate associated diseases.
Well, that wraps it up for your summaries. Now, for our feature discussion.
Today's feature paper really represents the first data we have that tells us what our cardiovascular health in middle age is doing to us in older age, in terms of both morbidity and longevity. To discuss this paper today, I'm so happy to have the first and corresponding author, Doctor Norrina Allen from Northwestern University in Chicago and Doctor Jarett Berry, associate editor from UT Southwestern. Welcome, both.
Dr Norrina Allen: Thank you very much.
Dr Jarett Berry: Thanks, Carolyn.
Dr Carolyn Lam: Norrina, could I start with you? This represents the 40 year follow up of the Chicago Heart Association detection project and industry. Could you maybe start by telling us a little bit about the Chicago Heart Association study?
Dr Norrina Allen: The Chicago Heart Association study was a large study that recruited almost 40,000 individuals who were employed in Chicago. They did a baseline exam between 1967 and 1973. After that baseline exam, we followed those individuals for over 40 years using their Medicare records, so we've been able to monitor their healthcare utilization and the incidence of disease across their lifetime up through 2010.
Dr Carolyn Lam: Then you measured their cardiovascular health by specific measurements, right? Could you tell us how that was defined and then also how was morbidity burden defined?
Dr Norrina Allen: Of course. We really think the overall burden of cardiovascular health tells us something more than looking at individual risk factors, so we classified each of the CHA participants into one of four groups, and each of those groups was defined by the level of main cardiovascular risk factors, including blood pressure, BMI, diabetes, smoking, and cholesterol level. We identified people who had favorable levels of all of those risk factors, individuals who had one elevated but not clinically of those high risk factors, individuals who had one high level, or individuals who had two or more high levels. That was based on their baseline exam. Overall we found that about 6% of the CHA participants had favorable levels of all of the risk factors at baseline, 19% had one or more that was elevated, 40% had one high, and 35% had two or more high risk factors, and again this was at the baseline exam when they were young to middle aged.
We then followed them, as I mentioned, using Medicare data and we identified the burden of whole morbidity based on the ICD9 codes in their Medicare record, and we identified the level of morbidity for each year of age, from entry into Medicare, [inaudible 00:11:54] all the way to their death.
Dr Carolyn Lam: And now, drum roll, your findings, they were pretty stunning.
Dr Norrina Allen: Yeah. As you mentioned when you introduced the study, this study is really the first to look at the whole of an individual's later life, meaning not just looking at the incidence of disease or longevity but taking those both into account. What we were particularly interested in was looking at the cumulative burden of morbidity in older age and the relative proportion of life that people live with cardiovascular or all cause morbidity. What we found was that individuals, who at baseline in young and middle age and favorable levels of all major cardiovascular risk factors, lived longer by almost four years but they also delayed the onset of all cause and cardiovascular morbidity by 4 and a half and almost 7 years respectively. What that means is that the proportion of their life that they live with morbidity was much shorter, they lived longer and healthier as compared to individuals who had one or two more high risk factors.
Dr Carolyn Lam: What an important public health message. Jarett, this concept of morbidity compression, tell us your thoughts.
Dr Jarett Berry: This is a really important paper. We've known for a long time, of course, that low risk individuals live longer, but the question of whether or not low risk individuals lived better throughout their life has been incompletely understood. The problem is that because low risk individuals live longer, the question that many have asked is that when we live longer is there a so-called expansion of misery, which some have talked about? That we live longer, but we have the same burden of disease or is that extended time horizon with the extended life span ... is the burden of morbidity compressed into a shorter period of time? In order to do that you need a couple things. You need a very large study that's followed for a very long time. Importantly, not just follow them for a long period of time, but follow enough individuals all the way until death so you know not just the first part of the story but we know the end of the story.
It really wasn't until [inaudible 00:15:18] paper, with not only the very large sample side but the very long term follow up until death, that we've been able to understand that actually low risk status in middle age does actually compress morbidity. This question of morbidity compression is not just an academic question but it actually has potential implications for cost savings and how we think about health care costs in our health care system. It'd be nice to hear [inaudible 00:15:18] thoughts about that as well, what else she found in regard to the Medicare costs.
Dr Norrina Allen: Right. As Jarett mentioned, not only from an individual perspective but at a societal level, what we're interested in is whether being in favorable cardiovascular health actually lowers healthcare costs at the same time as increasing an individual's health and longevity. What we found was that not only do the individuals in favorable health live longer and healthier, but they also have lower cumulative and annual healthcare costs, meaning that from a societal standpoint the compression of morbidity results in healthcare savings. We really think this is a strong method that provides support for earlier prevention efforts not only to improve an individual's quality of life but to reduce the healthcare costs associated with later life morbidity.
Dr Carolyn Lam: Indeed, what an important message to live longer and better and to save societal cost we need to get healthier cardiovascularly in middle age. Now, what really scares me though, is the statistic you told us a bit earlier. Only 6% of the individuals that you studied had a favorable level of all factors. What do you think this implies? What do you think needs to be done?
Dr Norrina Allen: Unfortunately, at this point, it's relatively rare in our population to reach middle age, 40 to 50 years of age, with favorable levels of all major cardiovascular risk factors. I think ... my research is really focused on trying to identify ways and times to intervene, to really help promote cardiovascular health early in life. I really think that we need to work hard to prevent the occurrence of these risk factors and the elevation of these risk factors much earlier in life. That means, even before the age of 40 and much earlier than that, we really need to be focusing on preserving cardiovascular health so that by the time individuals reach later life they can have a good quality of life and a longer, healthier life.
Dr Jarett Berry: I think the issue of the fact that low risk status is rare is that's a challenge that we continue to wrestle with as a society and as investagators interested in this are and how to improve that. When you look at your data, Norrina, I guess one silver lining here is we do see that ... when you look across the strata of risk groups ... it wasn't just the low risk individuals that seemed to benefit. It seemed that there was a little bit of a dose response. The goal obviously is to promote low risk status, but if we could limit the prevalence of those at the highest risk and shift them down a little bit, that could also have potential implications. I'd be interested to hear your thoughts about that.
Dr Norrina Allen: I think that's very accurate. There really is kind of a dose response level, so that every risk factor that's favorable adds a benefit and the more we can do to reduce the high risk factors over time, the better the long term outcomes are likely to be. I do really think prevention doesn't only have to exist before the development of the risk factors, but also there's a benefit to reducing risk factors that may have already developed or are elevated, and to try and reduce their level. I would say that I think that's an interesting next step that we really want to look at and try and think about how best to intervene even at middle age and help improve outcomes much later in life.
Dr Carolyn Lam: Thank you, listeners, for joining us today. I'm sure you agree, it's such an important message. Share it with your friends and tune in next week.