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.
Dr Greg Hundley: And I'm Dr Greg Hundley, director of the Pauley Heart Center at BCU Health in Richmond, Virginia.
Dr Carolyn Lam: So Greg, guess what? We are going to be discussing predicting the benefit of evolocumab therapy in patients with atherosclerotic disease using a genetic risk score. That's our featured paper this week coming from the results of the FOURIER trial. I bet you can't wait to discuss it, but I'm not going to let us until we talk about some of the papers in today's issue. Do you have one?
Dr Greg Hundley: Yes, Carolyn, but first I'm going to get a cup of coffee because there's a lot of data in this one. This study is from the ODYSSEY trial and it involves alirocumab and it's from Dr Charles Paulding. Remember Carolyn, the ODYSSEY trial was a randomized double-blind placebo-controlled trial comparing alirocumab, a PCSK9 inhibitor or placebo in 18,924 patients with acute coronary syndrome and elevated atherogenic lipoproteins despite optimized statin treatment. And the primary endpoint of this trial comprise death from coronary artery disease, non-fatal MI, ischemic stroke, or unstable angina requiring hospitalization. Now Carolyn, this is a sub-study and it was performed an A genome wide polygenic risk score for coronary artery disease comprising 6,579,025 genetic variants. And they were evaluated in 11,953 patients with available DNA samples. Analysis of the MACE risks, all those outcomes together, was performed in placebo treated patients while treatment benefit analysis was performed across all the patients.
Dr Carolyn Lam: Ooh, so what did they find?
Dr Greg Hundley: Well, Carolyn, both the absolute and relative reduction of MACE by alirocumab compared to placebo was greater in high versus low PRS patients. Those genetic, polygenetic risk scores combined in the patients. There was an absolute reduction by alirocumab in high versus low PRS groups of 6% and 1.5% respectively, and relative risk reduction in the alirocumab of 37% in the high PRS group versus 13% in the low PRS group. And so Carolyn, these results suggest the possibility of an independent tool for risk stratification using sort of precision medicine by selecting those using these genetic constructs, who may be more likely to benefit from this form of therapy.
Dr Carolyn Lam: Wow Greg, that is really interesting. I genuinely think that our world is moving towards precision medicine and this really, really speaks to remember that feature paper also talking about genetic risk scores, but from the FOURIER trial. But before we get to that, I've got a basic science paper. Now this one provides insights into the mechanisms underlying age related hypertension. And it's from Dr Ying Yu and colleagues from Tianjin Medical University who hypothesize that since proinflammatory cytokines increase in T lymphocytes with aging and prostaglandin D2 suppresses T helper 1 cytokines through the D-prostanoid receptor 1, that this axis in T cells may play a role in age related hypertension.
Dr Greg Hundley: Ah, Carolyn. What did they find in this study?
Dr Carolyn Lam: Prostaglandin D2 biosynthesis and D-prostanoid receptor 1 expression, were both markedly decline in CD4 positive T cells from older humans and aged mice. D-prostanoid receptor 1 depletion in these CD4 positive T cells, exaggerated age dependent blood pressure elevation in mice by increasing tumor necrosis factor alpha and interferon gamma secretion. Whereas its over expression showed the opposite effect and its activation suppressed TH1 cytokines. These results really indicate that D-prostanoid receptor 1 and its downstream pathway may serve as an attractive immuno-therapeutic target for age dependent hypertension.
Dr Greg Hundley: Oh wow. Very insightful Carolyn. Well, I've got a basic science paper to go over and it's from professor Kinya Otsu from Kings College London. This study addresses the mechanism of ongoing inflammation within the hearts of patients with cardiomyopathy. The study involves the assessment of Regnase-1 and RNAs involved in the degradation of a set of pro inflammatory cytokine messenger RNAs in immune cells. And the study involves the role of Regnase-1 in non-immune cells such as cardiomyocytes.
Dr Carolyn Lam: Wow.
Dr Greg Hundley: The degradation of cytokine messenger RNA by Regnase-1 and cardiomyocytes plays an important role in restraining sterile information in failing heart. Once the inflammatory cascade gets going, this is that constant inflammation that's ongoing. In addition, the Regnase-1 mediated pathway might be a therapeutic target to treat patients with heart failure as adeno-associated virus 9 mediated cardiomyocyte targeted gene delivery of Regnase-1 or administration of anti-IL-6 receptor antibody, attenuated the development cardiomyopathy induced by severe pressure overload in wild type mice.
Dr Carolyn Lam: Wow, that's really interesting. I find this whole field of inflammation in heart failure of course, of key interest, but I'm going to next tell you about the results of the FUEL trial, which is the Fontan Udenafil Exercise Longitudinal trial.
Dr Greg Hundley: Tell us about the Fontan operation.
Dr Carolyn Lam: Aha, I thought you may ask, Greg. Well, the Fontan operation to remind us all, really creates a total cavopulmonary connection and a circulation in which the importance of pulmonary vascular resistance is therefore magnified. Over time, the circulation needs to deterioration of cardiovascular efficiency associated with a decline in exercise performance. This FUEL trial and reported this time by David Goldberg and colleagues from the Children's Hospital of Philadelphia was a phase 3 clinical trial, which randomized 400 patients with Fontan physiology from 30 sites in North America and the Republic of Korea. The participants were randomly assigned to Udenafil at 87.5 milligrams twice daily or placebo. And the primary outcome was the between group difference in change in oxygen consumption with peak exercise.
Dr Greg Hundley: Hmmm, very large important trial it seems like Carolyn. What did they find?
Dr Carolyn Lam: Treatment with Udenafil did not result in a significant increase in peak oxygen consumption, which was the primary outcome, but did result in improvements in measures of exercise performance at the anaerobic threshold, which was a secondary outcome. Udenafil was well tolerated with side effects limited to those previously known to be associated with phosphodiesterase type 5 inhibitors.
These results and future perspectives are discussed an editorial called FUELing the Search for Medical Therapies in Late Fontan Failure, by Doctors Gewillig and De Bruaene.
Dr Greg Hundley: Very nice, Carolyn. Now how about the rest of the journal?
Dr Carolyn Lam: Oh well I want to tell you about this in-depth review by Dr Rosenkranz and it's entitled, Systemic Consequences of Pulmonary Hypertension and Right-Sided Heart Failure. Very intriguingly, talking about non-cardiac features, as well as cardiac, of right heart failure, a real, real must read with beautiful figures.
In the cardiovascular case series we discuss a case of left ventricular non-compaction and cardiogenic shock by Dr Shenoy. There are also two research letters I want to tell you about one by Dr Gillinov on the accuracy of the Apple watch for detection of atrial fibrillation. And this time looking at the Apple watch series 4, which interestingly employs electrodes to generate a single lead ECG and provides two mechanisms for rhythm assessment. Won't tell you more. You got to pick up this beautiful letter.
The next is by Dr Mazer on the effect of empagliflozin on erythropoietin levels IN stores and red blood cell morphology in patients with type II diabetes and coronary artery disease. And this really provides evidence to suggest that SGLT 2 inhibition with empagliflozin may stimulate erythropoiesis via an early increase in erythropoietin production in people with diabetes.
Dr Greg Hundley: You know Carolyn, we just keep hearing more about EMPA and DAPA and they are just going to really pave the way I think for a whole new class of agents that we're going to be using frequently.
I've got a couple letters in the mailbox and one is by Sugimoto and Taniguchi regarding the article, Internal Versus External Electrical Cardioversion of Atrial Arrhythmia in Patients with Implantable Cardio Defibrillators, a randomized clinical trial. And then also there's another research letter by Dr Hiroshi Sugimoto from Kobe Red Cross Hospital with a response by Jakob Lüker from University of Cologne.
What a great issue. How about we proceed to that feature article?
Dr Carolyn Lam: You bet.
Can a genetic risk score identify individuals who will derive greater benefit from PC SK9 inhibition? Well guess what? We're going to find out now in our feature discussion. So pleased to have with us the first and the corresponding authors of our feature paper, Dr Nicholas Marston and Dr Christian Ruff, both from the TIMI study group in Brigham and Women's Hospital and Harvard Medical School and also to have our lovely associate editor, Dr Svati Shah from Duke University in Durham, North Carolina. Welcome everyone.
Nick, could I get you started with telling us about this exciting analysis that you did from the FOURIER trial?
Dr Nicholas Marston: The FOURIER trial was a 27,000 patient cardiovascular outcomes trial that studied the PC SK9 inhibitor, evolocumab and it demonstrated a significant reduction in major adverse cardiovascular events in patients who had established atherosclerotic disease. And in the study, there was a 15% relative risk reduction and a 2% absolute risk reduction, which earned it a class 2 recommendation for very high-risk patients with atherosclerosis in the recent cholesterol management guidelines. And what we've done in previous lipid trials is we studied the interactions between genetic risk and treatment benefit. For example, in 2015 we showed that patients with high genetic risk, those in the top 20% of genetic risk, had the greatest benefit from statin therapy in terms of both absolute and relative risk reductions. And so now we have the opportunity with evolocumab and data from the FOURIER trial to ask the same question of PC SK9 inhibitor. That is, could a genetic risk score identify patients who will drive a greater treatment benefit and we hypothesize that like statins, there would in fact be a significant interaction between genetic risk and therapeutic benefit.
Dr Carolyn Lam: That's so cool Nick. But could I ask, the question always comes, is it nature versus nurture? And so I really love the way that you dealt with the clinical risk factors as well. Could you maybe walk us through that and then tell us the results?
Dr Nicholas Marston: Yes, absolutely. We for this study, kind of had two objectives. One was to look at risk prediction and then the other look at treatment benefit and using a genetic risk score for both. However, we wanted to go further than just use the genetic risk score. We wanted to incorporate clinical risk factors since that's how we would do it as physicians in the clinic. We would have not just genetic risk data in front of us but also clinical data. And so when we were grading a patient's risk using genetic risk, we also factored in if they had multiple clinical risk factors. And what we found by combining both genetic and clinical risk was that there was a significant gradient of risk across these risk categories.
That is patients who were without high genetic risk and without multiple clinical risk factors actually had no benefit from evolocumab over the 2.2-year follow-up period. However, those without high genetic risk, but who did have multiple clinical risk factors, derived an intermediate benefit. About a 13% relative risk reduction and 1.4% absolute risk reduction. And then it was the high genetic risk group, independent of whether or not they had multiple clinical risk factors that had the largest benefit from evolocumab with a relative risk reduction of 31%, absolute risk reduction of 4% and the number needed to treat of 25. And that's actually a twofold greater benefit than was seen in the overall FOURIER trial population.
Dr Carolyn Lam: That's really stunning results. Now I know Svati's going to have questions for us, so maybe I should invite you Svati, just put these results into context and let the audience know what we were thinking as editors when we saw this brilliant paper.
Dr Svati Shah: Yeah, thanks Carolyn. And I think Nick has done a fantastic job of describing the exciting results from this paper and just kind of taking a step back to help the audience understand what we're talking about when we're talking about genetics. For decades, we've been trying to figure out the genetics of heart disease and we're not talking about the genetics of things that are really rare like long QT syndrome, but the genetics of just common complex heart diseases. And amongst the scientific community, we've tried all different ways of sort of analyzing these data and so I want to make sure that everybody who's listening understands the novelty of really looking at these polygenic risk scores. Where we have now come to understand that it's not a single gene, it's not even two genes, that it's multiple variants and multiple genes and when they're combined, that's when you really have the power to understand how it might be useful in terms of how we take care of patients.
Really important with how Nick and Christian have laid out this really nice paper as well as their prior work in statins, is that not only did they show that these polygenic risk scores are associated with cardiovascular outcomes or even different amongst whether you get treated with the drug or whether you don't, but really importantly they're getting it clinical utility, not only with regards to showing that they compare it to a clinical risk score, but really showing that if you use these polygenic risk scores, you can identify patients who may derive the greatest benefit from PC SK9 inhibitors. And importantly in their paper, they show that if you have low polygenic risk score and low clinical risk score, you may not derive benefit from PC SK9 inhibitors. With all the caveats that this is a secondary prevention population, so I really applaud Christian and Nick and his team for the nice work that was done.
Dr Carolyn Lam: Oh, couldn't agree more, Svati. You know what I was very struck with too, because some people go, I may have a genetic risk. Maybe I could undo it or somehow overcome it with my clinical risk factors. And that's why I really appreciated that they showed that it was additive, and genetics still matter even if you have risk factors and vice versa. That was really cool. Christian, could I ask you to maybe describe a bit, what kind of genetic risk score this was and maybe perhaps point out some of the limitations therefore of what you studied.
Dr Christian Ruff: As Svati mentioned, this is really a quickly evolving field. We now have the ability to either genotype or sequence all of the variation that makes us different from one another. Our susceptibility to disease as well as our potential benefit for treatment. We had for this study, looked at several different risk scores. The one we focused on was a coronary artery disease genetic risk score that had 27 different variants that had been shown to predict having a cardiac event, both in primary and secondary populations. And we have previously identified patients who may have been at a higher risk who received greater benefit from statin therapy. And in this study, we actually compared this 27 variant genetic risk score with actually a much larger score of over six million variants. And interestingly, the two scores performed fairly similar with respect for risk prediction. One of the big questions going forward is, we have lots of ways to develop genetic risk scores, how many different variants do we need? What more information do we have with more complicated scores?
And I think Svati really hit on a really critical point is that really this study is really layering in genetic risk on top of clinical risk factors, which we can easily assess at the bedside. And I think what's reassuring to patients is that not only is genetic risk able to give us much more information for prognosis, but that this risk is modifiable. People think that their genetic risk, they're sort of born with it and there's nothing that they can do about it. But in this study, as Nick pointed out, even over a very short period of time with powerful lipid lowering therapy with a PC SK9 inhibitor, we essentially reduced these patients at high genetic risk to the risk of the very low risk patients on placebo. I think this is a reassuring message that genetics plays an important role for risk prediction and it identifies patients who we might target for more intensive therapy and that we can potentially reduce that risk even though that risk is based on the DNA that they're born with.
Dr Carolyn Lam: Indeed. That's a great point. And Svati, I'm sure you were thinking along those lines when you invited that beautiful editorial by Doctors Daniel Raider and Michael Levin. But Svati, would you like to comment on your thoughts on, is this ready for prime time?
Dr Svati Shah: I think that's the key question. What Christian and Nick and his team have done is take us a big step forward in how we use these polygenic risk scores. I think there still are many skeptics amongst the genetic scientific community about, well great, you can look at 27 variants and some of these polygenic risk scores, you're looking at a million things. How do we actually use that to take care of patients?
I actually want to turn this back, that question back around Carolyn, and I'd like to ask Christian next, what are the next steps? There are a lot of cardiologists who if you're listening to this podcast, should we all run out and get our patient's genotype to order this genetic chip so that we can figure out what their polygenic risk score is?
Dr Christian Ruff: Yeah, that's a great question and I could start off and then hand off to Nick, but I think one of the key questions is obviously there are a lot of genetic risk scores and I don't think as a field that we've come up with which one we really should implement in clinical practice. There's still a lot of fine tuning and figuring out which score gives us the most amount of useful information.
And then I think as something that you had mentioned that these scores are generated in both a healthy cohort population and now, we're looking at it in clinical trials and there's no sort of reference. Like when we have a blood test and we say, "If your hemoglobin A1C is above or below this number that means that you have diabetes." And we haven't figured out, what are the actual thresholds that you use for these genetic risk scores that you can implement broadly across different patient populations. There's still a lot of work that needs to be done to make these scores ready for prime time. This is really setting the stage. Is this something that we should be doing? And I think these studies and others say that the data looks great that we should be doing this, but we haven't yet figured out the logistics of which score and how do we actually reference to population.
Dr Nicholas Marston: Yeah, I agree with Christian definitely that we need to figure out what's the optimal genetic risk tool and for which population and what the cut points are. And then I think another piece that's going to be very important moving forward is doing a lot of this work and studying in non-European ancestry and cohorts and populations. Because most of the work done so far in discovery has been in databases such as the UK Biobank. And that limits us in our analyses to European ancestry patients. And so, I think for this to go to prime time, we want to be able to offer it to all of our patients. And so that means making sure we have scores that fit all populations, not just primary and secondary, but also all different types of ancestry.
Dr Carolyn Lam: Oh, I'm so glad you mentioned that, Nick. That was exactly on my mind coming from Asia. And the other thing of course, would be cost effectiveness of these approaches. Oh my goodness. I wish we had all the time in the world to talk about this more. The implications are enormous, but just let me thank you on behalf of all of us for publishing this remarkable paper in Circulation.
Audience, you've been listening to Circulation on the Run. Don't forget to tune in again next week.
Dr Greg Hundley: This program is copyright, the American Heart Association 2020.
Dr Biykem Bozkurt: I am Biykem Bozkurt, Professor of Medicine from Baylor College of Medicine, Senior Associate Editor for Circulation and today, I'm joined with Sana Al-Khatib, Professor of Medicine from Duke University, Senior Associate Editor of Circulation, for the podcast for the fourth annual Go Red for Women issue for Circulation. As all our listeners are aware, cardiovascular disease is a leading cause of death among women, but we have significant gaps in our awareness and treatments, and with a recognition of these disparities for cardiovascular care in women, AHA has launched a Go Red for Women campaign back in 2004. We have made great strides, and despite the improvement in awareness, significant gaps persist and adverse trends are emerging for cardiovascular disease in women.
With such recognition, in 2017, Circulation launched the annual Go Red for Women issue, dedicated to cover transformative science, exciting new treatment strategies, recent epidemiological trends, and with an intent to close the gaps and eliminate the disparities for cardiovascular care in women. This is the fourth Go Red for Women issue and we have an exciting portfolio that we'd like to share with our readers and listeners. In this issue, we have quite a few important papers. The first two that we would like to start with are going over the epidemiologic trends. Sana, do you want to walk us through the two papers that we have on myocardial infarction and sudden cardiac death?
Dr Sana Al-Khatib: I would love to start with the paper on sudden cardiac death, which is very fitting. That's what I focus most of my work on. This particular paper actually looked at sudden cardiac death as the first manifestation of heart disease in women, and it was focused on the Oregon sudden unexpected death study, the timeframe for which was between 2004 and 2016 and what they really wanted to do is to assess sex specific trends in sudden cardiac death incidence. And so they focused on out of hospital, sudden cardiac death cases among adults during that time period.
And they divided that 12-year period from February 2004 to January 2016 into three four-year intervals, 2004 to 2007, 2008 to 2011 and 2012 to 2015. And they really looked at these trends among women and men and they found that there were 2,938 sudden cardiac deaths, 37% of who were women. And they found an interesting U-shaped pattern of risk of sudden cardiac death with Anader in 2011. An increase in the years that followed 2011 so regarding that rebound, the rates really increased in 2013 and 2015. And when they specifically looked at women, they found that the rates of sudden cardiac death declined by 30% between the first and second four year time period and increased by 27% between the second and third period.
Interestingly, the subsets with sudden cardiac death as the first manifestation of heart disease, accounted for 58% of the total rebound in sudden cardiac death incidence from period two to three but there was no change in the incidence over time for sudden cardiac death occurring among people with preexisting heart disease. For men actually sudden cardiac death also declined from the first to the second period, but not as much as in women and also increased between the second and third periods. Again, not as much as we saw in women. Subsets of sudden cardiac death occurring in the setting of identifiable heart disease was responsible for 55% of the rebound in overall sudden cardiac deaths incidence. Certainly some significant differences between men and women. Very exciting findings.
Then if we actually turn our attention to the second study looking at sex specific trends in acute myocardial infarction, this particular analysis, Biykem, was done within an integrated healthcare network between 2000 and 2014 and they picked the Kaiser Permanente Southern California network. They were able to identify 45,000 plus acute MI hospitalizations between 2000 and 2014 and they found that age and sex standardized incident rates of AMI declined from 2000 to 2014. And they found that a decline for women was actually more so than in men. And in fact for men it was pretty much stable. And they found that the incidence of hospitalized MI had declined, however, declines are slowing among women compared with men in recent years.
That's actually identified some unmet care needs among women that hopefully can meet people and investigators to tailor their approaches to try to close those gaps and disparities in care. With that, let me actually turn it back to you to potentially talk about to cardiovascular risk assessments in women.
Dr Biykem Bozkurt: With the recognition of the disparities and the recent emerging trends of adverse outcomes, especially in younger women, there has been a focused attention in how to assess risk, cardiovascular risk in women. There is a very comprehensive review by Salim Virani and colleagues who's addressing the cardiovascular risk assessment for women. As our listeners will recall in 2018, ACC/AHA cholesterol professional guidelines specified risk enhancing factors such as premature menopause or preeclampsia for women. And if present, in borderline or intermediate risk patients, would elevate the 10 year risk to a higher category. But now with a recognition of many more risk factors, Virani and colleagues are proposing a more comprehensive cardiovascular risk assessment for women. And these include the risk factors that are not only identified in the 2018 ACC/AHA cholesterol guidelines, but additional such as gestational hypertension and diabetes or adverse pregnancy outcomes such as preterm delivery, small birth for gestational age or placental abruption or infarct or premature menarche or premature menopause, primary ovarian failure or pregnancy loss and additionally inflammatory disorders such as lupus, rheumatoid arthritis, psoriasis and history of cancer and cancer related therapies.
And they formulate this in a nice and well tabulated fashion. And all these risk factors are summarized table one which I think most of our listeners and readers will refer to. And they also come up with a nice approach. What shall we do? And how shall we detect that risk? First recommendation they have is that we should obtain a comprehensive obstetric and gynecological history from all women. And if these risk factors are present, then we should then screen for other traditional risk factors early and frequently and then treat for modifiable risk factors such as hypertension, hyperlipidemia, diabetes, metabolic syndrome, and also implement aggressive lifestyle modification with strategies such as management of blood pressure control, reduction of blood sugars, remaining active eating, healthy, losing weight, and not smoking. Which is summarized as life's simple seven which is an AHA initiative that summarizes healthy lifestyle as life's simple seven.
And very complimentary to Virani’s review paper, we had another wonderful paper that is titled Life's Simple Seven and health by Jacqueline Kulinski who reminds us that not only these seven factors but breastfeeding for postpartum mothers is an important approach to reduce cardiovascular risk. Breastfeeding is not only beneficial for the newborn infants but for the mother as it's been associated with reduction in risk of myocardial infarction, stroke, cardiovascular disease hospitalization rates, future development of diabetes, hypertension, and even mortality. And this paper elaborates on potential mechanisms such as increases in metabolic expenditure, enhancement of insulin sensitivity, reduction in cholesterol, greater mobilization of fat stores and reversal of elevated triglycerides and cholesterol that's seen during pregnancy.
It also emphasizes the importance of recognition and education of women because currently only about 25% of women are exclusively breastfeeding at six months and US has one of the lowest breastfeeding rates among industrialized countries. And we do have disparities according to race and income and black infants and infants living in rural areas in Southeast USA are less likely to be breastfed. And there is definitely increased recognition for importance and but it's also important to be able to accommodate and facilitate breastfeeding for mothers. Currently the paper emphasize that all 50 states now have laws allowing women to be able to breastfeed in public or private locations. But again, there definitely is a necessity for increased awareness and education.
On that end, there is also a great paper covering the news release announcing the partnership between American Heart Association and American College of Gynecology and Obstetricians in promoting risk identification and reduction of cardiovascular disease in women through collaboration between obstetricians and gynecologists. In 2018, AHA and American College of Gynecology issued a call for action for both specialists to team up and increase screening for cardiovascular disease by obstetricians and provide education and appropriate referrals. And I think this initiative is going to increase the opportunities for young women whose primary care provider solely could be an obstetrician, who potentially will get screened for cardiovascular disease and if they have these risk factors, will potentially be able to be offered lifestyle modification, message and intervention strategies.
These, I think, three very complimentary papers are enhancing our recognition for the new risk profile that needs to entail getting a comprehensive obstetric and gynecological history in all women. And in the event we recognize either of these risk factors including the traditional risk factors or obstetric and gynecological risk factors such as pregnancy related complications or preeclampsia or other additional special risk factors such as autoimmune disorders and cancer, then we will need to heighten our awareness for lifestyle modification, risk management, and earlier treatment and closer monitoring.
That brings us to another important risk profile, which is cancer for women. And Sana, I know we do have two great papers related to cancer topic. If you could elaborate on those.
Dr Sana Al-Khatib: I'm really excited about these papers. As you pointed out, Biykem, that cardio oncology is a field that is really expanding and so it was really very gratifying to get these two papers. The first paper had to do with a comparison between aromatase inhibitors and Tamoxifen in women with breast cancer in terms of their association with the risk of cardiovascular outcome. And this particular study was done in the United Kingdom and they studied women though with newly diagnosed breast cancer initiating hormonal therapy, either with everyone at aromatase inhibitors or Tamoxifen between 1998 and 2016. And the study outcomes that they were interested in included myocardial infarction, ischemic stroke, heart failure, and cardiovascular mortality.
And they actually had a sizable patient population with 23,000 plus patients included in this analysis of whom close to 18,000 initiated treatment with either an aromatase inhibitor or Tamoxifen. And they found that the use of aromatase inhibitors was associated with a significantly increased risk of heart failure and cardiovascular mortality compared with Tamoxifen and that aromatase inhibitors seemed to have a trend towards increased risk of myocardial infarction, ischemic stroke. Although those differences were not statistically significant. They actually concluded that aromatase inhibitors were associated with an increased risk of heart failure and cardiovascular mortality compared with Tamoxifen and that there were trends toward increased risks also of MI and ischemic stroke. And so they really want clinicians and patients to be aware of these findings when they are trying to make decisions about treatment for breast cancer.
We have another really interesting study, Biykem, that was actually a randomized control trial that studied the effect of exercise therapy dosing schedule on impaired cardiorespiratory fitness in patients with primary breast cancer. And so this randomized trial enrolled 174 post-menopausal patients who were randomly allocated to one of two supervised exercise training interventions, delivered either using a standard linear test or nonlinear test. And they had a control group of just stretching. They did some stretching. And they did the trial over at periods of 16 consecutive weeks and the primary endpoint was change in the VO2 level, PCO2 level from baseline to post intervention.
They had a couple of other secondary endpoints and their results were interesting. They found no serious adverse events during the trial, but they actually found that 40% of patients in both exercise dosing regimens were classified as responders. And they concluded that short term exercise training independent of dosing schedule was associated with modest improvements in cardiorespiratory fitness in patients previously treated for early stage breast cancer. Really interesting, a smaller study, not really looking at hard endpoints yet. It's still important because I believe that it is going to form the basis for more studies and more research in this important field, Biykem.
With this, I'd like to turn it over to you to talk about elevated body mass index in young women.
Dr Biykem Bozkurt: And this is another fascinating study, a large study from Sweden. It involved more than 1.3 million young women. Average age was 27. It was a national prospective cohort. The recruitment was between 1982 and 2014. What they did was they measured the baseline of weight of women in early pregnancy in the first trimester, actually the first antenatal visit before they could gain any weight related to the pregnancy. With their BMI measurement at baseline, then they followed these patients for approximately 30 years and associated this baseline BMI with future developments or dilated cardiomyopathy or any cardiomyopathy. They looked at that dilated cardiomyopathies, hypertrophic cardiomyopathies, these other cardiomyopathies such as alcoholic cardiomyopathy and others.
Interestingly, elevated body mass was associated with future development of dilated cardiomyopathy. A very similar finding was reported in former studies for adolescent men, but we didn't have this finding for young women. This study provides evidence that elevated BMI, even if it is only in the overweight range, is associated with future development of dilated cardiomyopathy. In the past we had numerous studies demonstrating overweight or obesity status being associated with future development of clinical heart failure, clinical symptoms of heart failure, but this is one of the largest scale population based cohorts demonstrating the association with dilated cardiomyopathy.
And interestingly, these women at baseline did not have the usual other confounders or comorbidities associated with future development of cardiomyopathy. The risk of diabetes and hypertension was less than 1% at baseline. Very interestingly, BMI by itself, independent of all these other variables was associated with future risk. And of course the higher the BMI was, the higher the risk was. The highest risk was for those with morbid obesity or BMI over 35 and in those patients the risk was increased by about five fold.
Sana, we talked about the disparities for women. Where are we with women participation in cardiovascular trials? And how do we looked globally overall regarding the disparity of cardiovascular diseases in woman?
Dr Sana Al-Khatib: These are really important questions, Biykem. Let me first start with a study that will be in the Go Red for Women issue on women's participation in cardiovascular clinical trials. They looked at that. Between 2010 and 2017, which is a very important topic as you know, Biykem. And so what they did here is they actually assessed the participation of women in completed cardiovascular trials that were registered in clinical trials between 2010 and 2017. And they parked calculated the female to male ratio for each trial to determine the prevalence adjusted estimates for participation of women. And so they kind of defined it as participation prevalence ratio. And so they said that they were able to identify 740 completed cardiovascular trials including more than 860,000 adults of whom 38% were women. And they talked about how the median female to male ratio of each trial was 0.501 overall and varied by age group and type of intervention and region and trial size and funding sponsors.
Actually, these are really interesting findings. In the interest of time, I'm not going to delve into all those details, but I think it would be really interesting for people to read that and look at this more carefully. But they found that relative to their presence in the disease population, the participation prevalence ratio of women versus men actually was a higher than 0.8 for hypertension, pulmonary arterial hypertension and lower for arrhythmia, coronary artery disease, acute coronary syndromes and heart failure trials. And they found that in the most recent time period, that they defined between 2013 and 2017, they saw a significant increase in the participation and prevalence ratios for stroke and heart failure trials compared to other periods. They concluded, not surprisingly, that among cardiovascular trials in the current decade, men still predominate overall, but that the representation of women actually is improving, especially when it comes to studies related to stroke and heart failure. That's what's really interesting, Biykem.
The other point that you were very nicely raised had to do with sex differences in primary and secondary prevention of cardiovascular disease. And the one study that we have in our issue, Biykem, was actually done in China. I really like this global reach of our issue. I presented a study that was done in the UK. You presented a study done in Sweden. This particular one was done in China and they conducted a community based survey of adults in seven geographic regions of China between 2014 and 2016. They really wanted to determine sex differences in the primary and secondary prevention of cardiovascular disease. And they looked at different factors in terms of age, education level, area of residence. And they had more than 47,000 participants of whom 61% were women. And they found that 5,454 had established cardiovascular disease, 57% of whom were women and 9,532 had a high estimated 10 year cardiovascular disease risk. And of those, 71% were women. And they found that only about 49% of women versus 39%, 60% of men were on any kind of blood pressure lowering medications, lipid lowering medications, antiplatelet therapy for primary and secondary prevention.
And they found that women with established cardiovascular disease were significantly less likely than men to receive blood pressure lowering medications, lipid lowering medications, antiplatelet therapy, so on, so forth. And that woman with established cardiovascular disease had better blood pressure control but less well controlled NVM cholesterol, were less likely to smoke and achieve physical activity targets. Conversely, women at high risk of cardiovascular disease were less likely than men to have their blood pressure LDL cholesterol, body weight controlled, despite the higher use of blood pressure lowering medication. Really interesting gaps in care that this study highlights that hopefully can form the basis for interventions to try to address those disparities.
And then as you know, we actually have a couple of research letters on the representation of women in editorial boards of major general and subspecialty cardiology journals, publishing clinical research. In this particular study, they actually found significant disparities where women were less represented among deputy associate editors and more so in European journals compared with US journals, general cardiology journals. Although editorial board membership was actually similar between Europe and the US, and they found that over 20 years, women deputy associate editors representation increased significantly for our journal, Biykem, Circulation. That was really very encouraging to see. And women editorial board membership increased for Circulation and for JACC without a significant change for the American Journal of Cardiology. That was really nice to see.
The one thing that was notable was in terms of women serving as editors-in-chief, we're still lagging behind in a big way, but I'm hoping that this particular study and several other studies that may get published in the future, will highlight these gaps and hopefully will lead to increased representation of women on editorial boards.
And finally we have an interesting study looking at the representation of women and men among training programs where they looked at the AAMC data and they were interested in looking at training in general cardiovascular disease medicine as well as for adult cardiology sub-specialties. And they also looked at pediatric cardiology by the way. And they found that in 2017 to 2018, among all adult cardiology trainees, only 21% were women. 79% were men. And among trainees in the different adult cardiology subspecialties, the representation was actually pretty poor in interventional cardiology, where only 10% of the trainees were women. And for electrophysiology, my own sub specialty, were only 11.6% of the trainees were women. Really interesting findings, the representation for advanced heart failure and transplant like your specialty, Biykem, women constituted 31% of the trainees and women did better when it came to adult congenital heart disease representing 47% of the training.
Really interesting trends and they concluded that in this review of ACG and the accredited training program, they found that cardiology ranked second for the most under representation of women, preceded as only by orthopedic surgery. And the sub specialty trends that I shared with you were really interesting. Hopefully as we see more of these publications, we'll be able to as a community come together and think about what are the barriers to more representation of women in these training programs? And how can we overcome these failures to encourage more women to go into this wonderful specialty of cardiology and the different sub-specialties, including procedural sub-specialties? Back to you, Biykem.
Dr Biykem Bozkurt: Thank you Sana. Very interesting findings indeed. Another fascinating study that we have in our issue is a study that provides us some insights on peripartive cardiomyopathy and potentially the role of natriuretic peptides during pregnancy.
This is an experimental study that involved natriuretic peptide receptor knockout in mice in which natriuretic peptides would not work. And the investigators demonstrated that these mice, during the postpartum lactation period, had elevated aldosterone levels, evidence of expression of pro inflammatory mediators such as IL-6, cardiac hypertrophy, fibrosis, left ventricular dysfunction, and even increased mortality. And interestingly, they were able to abrogate the effects of the lactation by use of mineralocorticoid receptor antagonists. With MRA use, there was evidence of reduction in LVH and reduction in inflammatory mediators.
There is a great editorial by Denise Hilfiker-Kleiner, who addresses the potential hypothesis of the role of unbalanced oxidative stress with prolactin in peripartum cardiomyopathy. And that the natriuretic peptides can be protected. And raises the question whether there could be a role for augmenting the natriuretic peptides further by use of sacubitril/valsartan. Or as was demonstrated in this study by you as a mineralocorticoid receptor antagonists in the postpartum period. And she also questions why in this experimental model, the detrimental effects were not seen during pregnancy but only in the postpartum lactation period.
Overall, very interesting papers. And finally we have an inspiring piece in our past or discovery section. It's an interview with Barbara Casadei, the President of European Society of Cardiology. She goes in a very detailed fashion over her career path, what she considers as the critical reasons for her success and how she envisions to shape the future of women in cardiology.
Dr Sana Al-Khatib: We would like to thank everyone who submitted their research and their work for this issue and congratulate the authors and investigators who were successful in getting their work published. Thank you very much.
Dr Biykem Bozkurt: We thank you for tuning in to our podcast. We hope that you'll enjoy our fourth issue for the Go Red for Women as we continue to highlight some of the best science for cardiovascular disease in women. Thank you.
This program is copyright, the American Heart Association 2020.
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.
Dr Greg Hundley: And I'm Dr Greg Hundley, associate editor, director of the Pauley Heart Center at VCU Health in Richmond, Virginia. Well, Carolyn, our feature article this week relates to an international multi-center evidence-based reappraisal of genes reported to cause congenital long QT syndrome. But, before we get to that, how about if we grab a cup of coffee and start on our other papers? Do you have one you'd like to discuss?
Dr Carolyn Lam: Yes. My favorite part of the week. So this first paper really asks the question, "What's the association between HDL functional characteristics, as opposed to HDL cholesterol levels, and acute coronary syndrome?" The paper comes from Dr Hernáez from IDIBAPS in Barcelona, Spain and colleagues who conducted a case control study nested within the PREDIMED cohort.
Originally a randomized trial where participants followed a Mediterranean or low-fat diet. Cases of incident acute coronary syndrome were individually matched one is to two to controls by sex, age, intervention group, body mass index, and follow-up time. The authors measure it the following functional characteristics, which were HDL cholesterol concentration, cholesterol efflux capacity, antioxidant ability, phospholipase A2 activity and sphingosine-1-phosphate, apolipoproteins A1 and A4, serum amyloid A and complement 3 protein.
Dr Greg Hundley: Wow Carolyn, a detailed analysis. What did they find?
Dr Carolyn Lam: They found that low values of cholesterol efflux capacity, and levels of sphingosine-1-phosphate and apolipoprotein A1 in HDL or all associated with a higher risk of acute coronary syndrome in high cardiovascular risk individuals, irrespective of HDL cholesterol levels and other cardiovascular risk factors. Low cholesterol efflux capacity values and sphingo-1-phosphate levels were particularly associated with an increased risk of myocardial infarction, whereas HDL antioxidant or anti-inflammatory capacity was inversely related to unstable angina.
Now this is significant because it's the first longitudinal study to comprehensively examine the association of several HDL function related biomarkers with incident acute coronary syndrome beyond HDL cholesterol levels in a high-risk cardiovascular risk population.
Greg Hundley: Very nice. Carolyn. It sounds like function over just the levels is important.
Dr Carolyn Lam: Exactly, you summarized it well. Well Greg, I've got another paper and I want to pick your brain first. Is it your impression that type 2 myocardial infarction, the type that occurs due to acute imbalance in myocardial oxygen supply versus demand in the absence of atherothrombosis, do you think that this type of MI is on the rise? It seems more and more common in my country.
Dr Greg Hundley: Do we want to say it's on the rise? Certainly by measuring all these high sensitivity troponins, et cetera, we're finding, I think, more evidence of type 2 MI. So, all in all, yeah it probably is on the rise, but likely related to some of our measurement techniques.
Dr Carolyn Lam: Oh, you are so smart, Greg. Because this paper that I'm about to tell you about really addresses some of these issues and it's from corresponding author Dr Gulati from Mayo Clinic in Rochester, Minnesota. And they really start by acknowledging that despite being frequently encountered in clinical practice, the population base incidents and trends of type 2 myocardial infarction is unknown and long-term outcomes are incompletely characterized. So they prospectively recruited 5,640 residents of Olmsted County, Minnesota who experienced an event associated with cardiac troponin T greater than 99th percentile of a normal reference population, which is greater than or equal to 0.01 nanograms per milliliter. And this was between 2003 and 2012, so very careful to talk about which Troponin T assay exactly to the point you discussed earlier, Greg. The events were retrospectively classified into type 1 versus type 2 MI using the universal definition.
Dr Greg Hundley: So Carolyn, what did they find?
Dr Carolyn Lam: They found that there was an evolution in the types of MI occurring in the community over a decade with the incidence of type 2 MI now being similar to type 1 MI. Adjusted long-term mortality following type 2 MI is markedly higher than after type 1 MI and that's driven by early and non-cardiovascular deaths. Mortality of type 2 MI is associated with a provoking factor and is more favorable when the principle provoking mechanism was an arrhythmia compared with postoperative status, hypotension, anemia or hypoxia. And these findings really underscore the healthcare burden of type 2 MI and provide benchmarks for clinical trial design.
Dr Greg Hundley: Very nice, Carolyn. Well, my paper comes from type 5 long QT syndromes and an analysis. And it's from Dr Jason Roberts from Western University. Through an international, multi-center collaboration, improved understanding of the clinical phenotype and genetic features associated with rare KCNE1 variants implicated in long QT 5 was sought across 22 genetic arrhythmia clinics and four registries from nine countries that included 229 subjects with autosomal dominant long QT five. So there were 229 of those subjects. And then 19 individuals with the recessive type 2 Jervell and Lang-Nielsen syndrome. The authors compared the effects of clinical and genetic predictors on a composite primary outcome of definite arrhythmic events, including appropriate implantable cardioverter defibrillators shocks, aborted cardiac arrest, and sudden cardiac death.
Dr Carolyn Lam: Wow. What did they find?
Dr Greg Hundley: Well, several things, Carolyn. First, rare loss of function KCNE1 variants are weakly penetrant and do not manifest with a long QT syndrome phenotype in a majority of individuals. That's a little bit of a surprise. Second, QT prolongation and arrhythmic risk associated with type 2 Jervell and Lang-Nielsen syndrome is mild in comparison with the more malignant phenotype observed for type 1 Jervell and Lang-Nielsen syndrome. And then number three, all individuals possessing a rare loss of function KCNE1 variant should be counseled to avoid QT prolonging medications and should undergo a meticulous clinical evaluation to screen for long QTS phenotype.
And then finally, Carolyn, the last finding, in the absence of a long QTS phenotype, more intensive measures, such as beta blockade and exercise restriction, may not be merited.
Dr Carolyn Lam: Oh, very interesting. Well, I've got one more original paper and in this, authors describe a new cellular mechanism linking ischemia-reperfusion injury to the development of donor specific antibody, a pathologic feature of chronic antibody-mediated rejection, which mediates late graph loss. This paper is from corresponding author Dr Jane Witt from Yale University School of Medicine and colleagues who use humanized models and patient specimens to show that ischemia-reperfusion injury promoted elaboration of interleukin 18 from endothelial cells to selectively expand alloreactive interleukin 18 receptor 1 positive T peripheral helper cells in allograph tissues and this promoted donor specific antibody formation.
Dr Greg Hundley: Carolyn, here's the famous question. What does that mean clinically for us?
Dr Carolyn Lam: Aha, I'm prepared. Therapies targeted against endothelial cell derived factors like interleukin 18 may therefore block late complications of ischemia-reperfusion injury.
Dr Greg Hundley: Very nice. Sounds like more research to come. Well, how about other articles in the issue?
Dr Carolyn Lam: Well, I'd love to talk about a white paper from Dr Al-Khatib, and it's about the research needs and priorities for catheter ablation of atrial fibrillation and this is a report from the National Heart, Lung, and Blood Institute Virtual Workshop.
Dr Greg Hundley: Well, I've got another arrhythmia paper, so this is from Professor Michael Ackerman at the Mayo Clinic and its minor long QT gene disease associations by coupling the genome aggregation database. It's a harmonized database of 140,000 or more exomes and genome derived in part from population-based sequencing projects, with phenotypic insights gleaned from a large long QT syndrome registry to reassess the strength of these minor long QT syndrome gene disease associations. Next, Carolyn, in an on my mind piece, Professor Gerd Heusch from University of Essen Medical School discusses, how can the many positive preclinical and clinical proof of concept studies on reduced infarct size by ischemic conditioning interventions and cardioprotective drugs be reconciled with the mostly neutral results in regard to clinical outcomes.
The author discusses the important differences between animal models that have been used a lot in this ischemia reperfusion and infarct size reduction science, and then the clinical scenarios of STEMI in humans as well as the many aspects of coronary reperfusion. How is that affecting the myocytes? How is that affecting the microcirculation, et cetera, that must be addressed? And then finally Carolyn, there is a series of letters, one from Professor Oliver Weingärtner from Universitätsklinikum Jena and another from Professor Yasuyoshi Ouchi from Toranomon Hospital. They're exchanging letters debating the utility of lipid lowering with Ezetimibe in individuals over the age of 75 years.
Dr Carolyn Lam: Very nice, Greg. Thanks so much. Shall we now move to our future discussion.
Dr Greg Hundley: You bet.
Well, welcome everyone. This is our feature discussion and today we're going to hear more about long QT syndrome. We have Dr Michael Gollob from University of Toronto and our own associate editor, Dr Sami Viskin from Tel Aviv Medical Center. Good morning. Good afternoon, gentlemen. Before we get started with a discussion of some of the study findings and results, Michael, could you tell us a little bit about why you performed the study and what were some of the hypotheses you wanted to test?
Dr Michael Gollob: As you know, long QT syndrome is probably the most recognized channelopathy associated with sudden cardiac death in young individuals and adults. And at the present time, there are 17 genes available for clinical genetic testing in cases of suspected long QT syndrome. We simply ask the question, "Is there sufficient scientific evidence to support that each of these genes are single gene causes of long QT syndrome based on our contemporary knowledge of genetics and the human genome?
Dr Greg Hundley: Great, Michael. So, can you tell us a little bit about your study population? How did you go about this and what was your study design?
Dr Michael Gollob: We designed a methods approach that would assure that any conclusions that were made from our working group were not based on the opinions of one or two individuals. We wanted to ensure that this was a consensus conclusion with multiple experts in the field including genomic scientists, genetic counselors, inherited arrhythmia experts, and researchers in the field. We created three independent teams of genetic experts to curate the genetic evidence reported in the medical literature for each of these 17 reported causes of long QT syndrome. This was essentially an evidence-based approach using a pre-specified evidence-based matrix or scoring system depending on the level of evidence, genetic primarily, in the reported literature for each gene.
Each of these curation teams worked independently of each other and they were blinded to each other's work and they were tasked with concluding whether a gene, based on the medical literature and the resource methodologies, had sufficient evidence for disease causation. Their classifications would be one of disputed evidence, limited evidence, moderate evidence, strong or definitive evidence for claims towards disease causation. Remarkably, independently, all of these teams reached the same conclusion. In the end, their summary data was reviewed by a clinical domain expert panel with individuals with expertise, particularly in long QT syndrome and other channelopathies. So in total 19 individuals reviewed all of the literature and the data presented and came to unanimous conclusions for each gene.
Dr Greg Hundley: Out of the 17, were there some that were more important than others or was it uniformly all 17 were relevant?
Dr Michael Gollob: Well, I think the most relevant conclusions of our study are that nine of these genes, more than half of these genes, were felt not to have sufficient evidence to support their causation as a single gene cause for typical long QT syndrome. So nine genes that are currently tested by clinical genetic testing providers do not have enough evidence to support their testing in patients with suspected long QT. And to us, that is the most relevant observation because testing genes that do not have sufficient evidence for disease causation poses a significant risk to patient harm and family harm. We concluded that only three genes had very definitive evidence for causation of long QT syndrome. Those three genes were KCNQ1, KCNH2, and SCN5A. There were another four genes that were concluded to have strong or definitive evidence for unusual presentations of long QT syndrome. And by that, I mean presentations that typically occur in the neonatal period and are associated with heart block seizures or developmental delay or in the case of one of these genes, Triadin, an autosomal recessive form of the disease.
Dr Greg Hundley: So helping us perhaps what types of genes to screen for when we have someone with this condition or suspected. So Sami, can you help us put this into perspective? How does this study help us in management of this clinical situation.
Dr Sami Viskin: In Circulation, we immediately recognize the importance of the manuscript, the importance of the study because unfortunately, there are too many physicians all over who will accept the results of genetic testing essentially like gospel. Now it's in the DNA, it's in the genes, so whatever you find must be true. And too often, clinical decisions on treatment including ICD implantation have been undertaken based on results of genetic testing’s; thus are wrongly interpreted. So we recognize immediately the importance of this paper. We already had a different study by Dr Gollob and his associates. Again, reassessing the role of genes in Brugada syndrome. So we were familiar with this type of analysis.
We recognize the importance and we moved ahead to accept this paper, it went fairly easily, I think only one revision. At the same time, we were getting additional paper by other groups. So in the same issue, we have two more papers, one from Jason Roberts with the International Long QT Registry of long QT 5, reaching similar conclusions that this is a gene with very limited penetrants and another study by the Mayo clinic also showing that many of the genes who are not the major genes are overrepresented in the healthy population. So we put all these three papers together with a very nice editorial by Chris Semsarian in the same issue. So everything is put in the right perspective of how we should be looking at all the genes of these disease in a different way.
Dr Greg Hundley: So as a clinician quickly, how can I use this information in the issue, perhaps this paper and all three, in management of patients with either suspected or long QT syndrome?
Dr Michael Gollob: First off, I would emphasize that the diagnosis of long QT syndrome or any genetic base disease for that matter, should be based on clinical phenotype and not the observation of a genetic change, particularly if genes are being tested that do not have strong evidence for disease causation, as is the case for the nine genes that we've pointed out in this manuscript.
So I think clinicians need to be wary of the genetic testing panels that they are requesting be screened or used in the assessment of their patients and be knowledgeable that at this point in time, we really only have three genes with very strong evidence to support disease causation of the typical form of long QT syndrome. And that for the most part, these other genes should not be tested or should only remain in the realm of research.
I think that responsibility extends further than just the clinician taking care of the patient, but also clinical genetic testing providers, companies that offer these genetic testing services. I think they should assume a responsibility to ensure that they are only offering services for genes that have strong evidence for disease causation because when they report results in genes that are not valid for the disease, that only confuses the care of the patient and that creates a risk of harm to them if that information is misinterpreted by a physician.
As Dr Viskin or Sami pointed out, we do see patients who are inappropriately diagnosed. We remove the diagnosis of roughly 10 to 20% of cases in our own clinic. And unfortunately, many of these patients and their families have suffered undue anxiety. Some of them have ICDs in place that should not have been there. So I think overall, the field needs to be aware of what genes are relevant and what genes still are within the realm of research.
Dr Greg Hundley: Can you tell us just quickly Michael and then also Sami, what do you see as the next study in this field?
Dr Michael Gollob: We're taking a step back now. The first decade of this century saw an exponential growth in reported gene disease associations. And now in the last five or six years, we've learned a lot about human genetic variation, which has provided us an opportunity to reflect back on some of these previous and reported genes as causes for long QT and other diseases.
So I think many individuals in our field may say, "Well, you know, this is disappointing. We believed in these genes. We really thought these genes were causes of long QT." And to that point I would say, we need more research. If you believe in some of these genes that have now been considered to have limited or disputed evidence, research should continue if these remain plausible candidates for the disease.
So I think future research has to continue. There are probably still a few other genes that have not yet been discovered. I think we've got the vast majority. I think in most cases, at least in our experience, 90 to 95% of cases are explained by the top three genes. But there are probably other genes out there and it's always fascinating to learn or discover new genes, but those sorts of studies have to be done with the correct methodologies and rigid protocols. Lastly, I think in the future us clinicians and geneticists and genetic counselors need to work closely with genetic testing providers to ensure that they are offering responsible genetic testing services.
Dr Greg Hundley: Sami, do you have anything to add?
Dr Sami Viskin: Just congratulate the authors. I think they did a very great service to the medical community by pointing out the limitations of the genetic testing and the way we interpret the results, and they deserve to be applauded for reminding us that we have to be careful when we read papers about genetic results or when we get genetic testing results ourselves.
Dr Greg Hundley: I want to thank Michael from University of Toronto and Sami from Tel Aviv Medical Center for participating. And on behalf of both Carolyn and myself, wish you all a great week and look forward to chatting with you next week.
This program is copyright, the American Heart Association 2020.
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.
Dr Greg Hundley: And I'm Dr Greg Hundley, Director of the Pauley Heart Center at VCU Health in Richmond, Virginia.
Dr Carolyn Lam: Greg, this issue is full of super interesting papers, many of which were presented as late-breaking presentations at the American Heart Association, like the feature paper that sacubitril/valsartan across the spectrum of ejection fraction in heart failure, where this was really analyzed across the landmark PARADIGM and PARAGON trials. I'm sure everyone's looking forward to hearing about it, but before we talk about that, I want to share some more very interesting results from a very important trial, the REDUCE-IT trial.
So, as some background, some trials have found that patients from the United States derive less benefit than patients enrolled outside the United States. And this was the reason that there was a pre-specified subgroup analysis of the REDUCE-IT trial, which really is the reduction of cardiovascular events with icosapent ethyl-intervention trial, and this analysis was conducted to determine the degree of benefit of icosapent ethyl in the United States.
So, Greg, do you remember what the REDUCE-IT trial was about?
Dr Greg Hundley: Well, Carolyn, I think REDUCE-IT randomized 8,179 statin-treated patients with triglycerides between 135 and 500 milligrams per deciliter and LDL cholesterol levels between 40 and 100 milligrams per deciliter and a history of atherosclerosis or diabetes to Icosapent Ethyl, four grams per day or placebo. And the primary endpoint, I believe, was cardiovascular death, nonfatal myocardial infarction, non-fatal stroke, coronary revascularization or hospitalization for unstable angina. Hah!
Dr Carolyn Lam: Wow, Greg, you pass that quiz, like maybe you had a cheat sheet answer.
Dr Greg Hundley: All right, Carolyn, tell us now what did REDUCE-IT USA find?
Dr Carolyn Lam: This was from a corresponding author, Dr Deepak Bhatt, from Brigham and Women's Hospital Heart and Vascular Center, and his colleagues and they found that in the United States Icosapent Ethyl at four grams a day produced large and significant reductions in multiple ischemic endpoints including cardiovascular death, myocardial infarction, stroke, coronary revascularization, and hospitalization for unstable angina. Furthermore, REDUCE-IT US demonstrated that Icosapent Ethyl provided a statistically significant 30% relative risk reduction and a 2.6% absolute risk reduction in all-cause mortality. The risk benefit profile of Icosapent Ethyl was highly favorable with an overall safety and tolerability profile virtually identical to placebo.
Dr Greg Hundley: Wow, Carolyn. So, this does have important implications for us in the US, very nice. Thank you for that lovely quiz. So, Carolyn, I'm going to switch now and talk about a paper from Roddy Walsh from Amsterdam in the Netherlands. In this study, the investigators defined the frequency of rare variation in 2,538 patients with dilated cardiomyopathy across protein-coding regions of 56 commonly tested genes and compared this to both 912 confirmed healthy controls and a reference population of 60,706 individuals to identify clinically interpretable genes robustly associated with dominant monogenetic dilated cardiomyopathy.
Dr Carolyn Lam: Wow, wow. That's a huge study. So what did they find?
Dr Greg Hundley: Okay, Carolyn. So overall rare variants in 12 genes potentially explain 17% of cases in the outpatient clinical cohort representing a broad range of adult patients with dilated cardiomyopathy and 26% of cases in the diagnostic referral cohort enriched in familial and early onset dilated cardiomyopathy. And so, practically speaking, by analyzing two dilated cardiomyopathy cohorts with distinctive patient profiles, the authors were able to comprehensively evaluate the genetic basis of dilated cardiomyopathy and identify variant classes that were particularly associated with early-onset disease. By restricting analyses to validated and interpretable genes and variant classes, the authors hoped in this study to increase the accuracy and reduce the uncertainty associated with genetic testing in dilated cardiomyopathy.
Dr Carolyn Lam: Very nice, very practical information. Well, my next paper is, I have to admit a super favorite topic of mine, and that is sex differences in heart failure. Now as a reminder to everybody, women represent over half of patients with heart failure with heart failure preserved ejection fraction, and there are multiple effective drug and device therapies for HFrEF, or heart failure reduced ejection fraction, but none approved for HFpEF. Thus, there is a greater so-called failure therapeutic deficit in women compared to men. So, does the recently presented PARAGON trial provide answers?
Dr Greg Hundley: Ah, Carolyn, you were involved in the PARAGON trial. Maybe tell us a little bit about that first to help us get oriented.
Dr Carolyn Lam: I would love to. So PARAGON compared sacubitril/valsartan with valsartan in patients with HFpEF. The primary outcome was a composite of first and recurrent hospitalizations for heart failure and death from cardiovascular causes, and the trial overall narrowly missed this primary outcome. However, an intriguing result in PARAGON was a significant sex-by-treatment interaction. And this was explored further in the current pre-specified subgroup analysis of outcomes by sex, which was reported by John McMurray from University of Glasgow and his colleagues.
Dr Greg Hundley: Ah, so I'm interested. What was this interaction?
Dr Carolyn Lam: Ah, so here is how the interaction work. Now, remember this was multi-variably adjusted significant in a pre-specified large subgroup of PARAGON. And what we found was that as compared with valsartan, sacubitril/valsartan seem to reduce the risk of heart failure hospitalization more in women than in men. Now, while the possible sex-related modification of this effect of treatment has potential explanations, the current study really cannot provide a definitive mechanistic basis for this finding.
Dr Greg Hundley: Very interesting. So, perhaps then, in heart failure preserved ejection fraction, sacubitril/valsartan could be very helpful in women.
Dr Carolyn Lam: Yes, and perhaps especially those with each ejection fraction in the lower ejection fraction range. And that is coming up in our future discussions, so let's not preempt it. You got another paper, Greg?
Dr Greg Hundley: Absolutely, Carolyn. My next paper is from Professor Irene Lang at the Medical University of Vienna, and it's related to microvascular disease and chronic thromboembolic pulmonary hypertension and hemodynamic phenotyping and histomorphometric assessments. So, Carolyn, pulmonary endarterectomy is the gold standard for treatment of patients with operable chronic thromboembolic pulmonary hypertension. However, persistent pulmonary hypertension after PEA or endarterectomy remains a major determinant of poor prognosis.
Dr Carolyn Lam: Ah, so are there any possible solutions to this?
Dr Greg Hundley: Well, Carolyn, today it is thought that a concomitant small vessel arteriography in addition to major pulmonary artery obstruction may play an important role in the development of persistent pulmonary hypertension and survival after pulmonary endarterectomy. One of the greatest unmet needs in the current preoperative evaluation is to assess the presence severity of small vessel arteriopathy.
Dr Carolyn Lam: Huh, that makes a lot of sense. So what did the authors do? What they find?
Dr Greg Hundley: Okay. Well, Carolyn, they had 90 patients with 49 of them receiving lung wedge biopsies for validation. So, in analyses incorporating receiver operating characteristic curves, pulmonary vascular resistance measures and larger arterial upstream resistance beds predicted persistent pulmonary hypertension after pulmonary endarterectomy, and certain values identified patients with poor prognosis after endarterectomy. Therefore, perhaps this form of analysis could be helpful in establishing prognosis in these patients and perhaps suitability for future interventions.
Dr Carolyn Lam: Wow, very interesting. Well, we were saying this issue's full of very important papers, and that also includes research letters. There's a research letter by Dr Cannon talking about evaluating the effects of canagliflozin on cardiovascular and renal events in patients with type 2 diabetes and chronic kidney disease according to baseline HbA1c, including those with an HbA1c less than 7%. And these are very interesting results from the CREDENCE trial that was also presented at the American Heart Association.
There's a research letter by Dr Jackevicius on the population impact of generic valsartan recall in Ontario, Canada, that really highlights the potential burden and risks associated with recalls of chronic oral medications used by large populations. And in Cardiology News, Bridget Kuehn talked about cardiovascular risk biomarkers, high-sensitivity cardiac troponin T and NT-proBNP and talked about how these two biomarkers may help clinicians stratify which patients may benefit the most from therapies for hypertension or diabetes. And this was according to a pair of studies presented, again, at the American Heart Association.
Dr Greg Hundley: Well, Carolyn, that's quite a nice review. I've got just a couple more papers to discuss. There's a perspective piece from Dr Ben Levine and colleagues from UT Southwestern that discusses whether a simple physical exam and maneuvers could actually supplant tilt-table testing. He provides arguments as to whether we should continue with tilt-table testing given the high rate of false positives. And then lastly, from the Mailbag, Dr Shuyang Zhang from Peking Union Medical College Hospital and the Chinese Academy of Medical Sciences provides a letter to the editors regarding a prior publication on the clinical applicability of the awareness of androgen-deprivation therapy's effects on ventricular repolarization. And Dr Joe-Eli Salem from Vanderbilt University provides his response.
Well, Carolyn, how about onto that feature?
Dr Carolyn Lam: Let's go. Our feature discussion today is all about left ventricular ejection fraction. Ah, that measure we both love and hate in the world of heart failure, I think. And this paper is truly remarkable, in my opinion. It is the look at the effect of sacubitril/valsartan across the spectrum of left ventricular ejection fraction in the PARADIGM and PARAGON trials. And I'm just so pleased to have none other than the first and corresponding author, Dr Scott Solomon, from Brigham and Women's Hospital and Harvard Medical School, as well as our Senior Associate Editor, Dr Biykem Bozkurt, from Baylor College of Medicine as well.
Scott, could you start by telling us about this analysis and why the opportunity to do such a special analysis in this paper?
Dr Scott Solomon: This was a really fantastic opportunity because, as you know, we did these two trials, PARADIGM and PARAGON, not at the same time but essentially in series. PARADIGM was a trial of patients with heart failure reduced ejection fraction, so ejection fraction of 40%, and PARAGON was a study of patients with heart failure with preserved ejection fraction. And the interesting thing is that, with the exception of ejection fraction, the criteria for enrolling patients in these trial was virtually the same.
In other words, we enrolled patients with signs and symptoms of heart failure, some elevation in natriuretic peptides, and we followed them. So it's really an extraordinary dataset of 13,195 patients in whom we can look at heart failure across that full spectrum of ejection fraction. We haven't been able to do this really since the CHARM study, which enrolled about 8,000 patients across the spectrum of ejection fraction. And it gave us an opportunity to look at a number of things including the effect of sacubitril/valsartan across that full spectrum of ejection fraction.
Dr Carolyn Lam: Great. And, Scott, you want to tell us what you found?
Dr Scott Solomon: When we pooled 13,195 patients, and by the way, this was a pre-specified analysis that we had decided to do prior to unblinding PARAGON. We see that if we put them all together, all these patients together, and just treat them as one group, we see that for every endpoint that we looked at, whether heart failure, hospitalization and cardiovascular death, cardiovascular death, all-cause mortality, whether we look at the time to first event endpoints or the total number of heart failure hospitalizations, we see a significant benefit in patients receiving sacubitril/valsartan compared to patients receiving either enalapril in the PARADIGM study or valsartan in the PARAGON study.
Now, what we also saw though, and this is probably most important, is that there appears to be an attenuation of the treatment effect as ejection fraction rises. Now we know that patients with higher ejection fractions tend to have a lower frequency of these events such as heart failure, hospitalization and cardiovascular death. But we also see here that as ejection fraction goes up that the benefit of sacubitril/valsartan appears to wane, especially when you get over about 60, an ejection fraction of about 60%. We've looked at this in categorical ways and also looking at a continuous spline analysis throughout the entire spectrum.
Dr Carolyn Lam: Yeah, I love that, and I just need to point every listener right now to figures 3 and 4 of your paper. I have a feeling we're going to be seeing these figures in a lot of talks and cited everywhere. Biykem, could I bring you in on this? What are the implications of something like this?
Dr Biykem Bozkurt: The interesting findings from the pooled data are, first, support of what we had seen in PARADIGM, meaning the lower the EF, the more the benefit or the higher the benefits. And as we had seen in PARAGON, which did not show an improvement in the combined endpoint with treatment with sacubitril/valsartan in patients with heart failure with preserved ejection fraction. In the pooled analysis as the EF got higher, there didn't seem to be any benefit, but the interesting, perhaps group of patients that the pooled analysis allowed us to have a deeper dive into was heart failure with mid-range EF. And we can crudely perhaps define this as ejection fraction between 40 and 50%. And by certain analyses, which again this is in the post-hoc and also in a continuous analysis and a specific analysis and a cubic spline analysis, it appeared that the benefit extended into those individuals with mid-range ejection fraction.
Again, we need to keep several points in consideration. One is ejection fraction can vary over time and is not a very precise measurement. There's definitely inter-reader as well as intra-reader variability and is not a good mayor of contractile performance. And we tend to actually have a significant amount of a specific infiltrative cardiomyopathies in that EF range, which tend to be excluded from usual clinical trials. And with that caveat, having kept this in mind, it's also important to recognize from cohorts and population-based studies, about 10 to 20% of our patients currently reside in that have HeFmrEF or heart failure with mid-range EF status. And thus the findings are intriguing, hypothesis generating and also encouraging that we may see perhaps benefits with RAS antagonism in individuals that do have LV systolic dysfunction.
And probably, if this is persistent and a clear reflection of a phenotype that reflects itself as reduced ejection fraction, probably the patient may benefit. Again, these results may need to be supported by future studies, and also we need to keep in mind that infiltrative cardiomyopathies, such as amyloidosis or sarcoidosis or others, were not included in these studies.
Dr Carolyn Lam: Thank you, Biykem. Go ahead, Scott.
Dr Scott Solomon: Carolyn, I agree with many of Biykem's points. I think that this middle range, and you and I kind of coined that term, heart failure with mid-range injection fraction, a number of years ago. The problem, of course, is knowing where that range exactly is, and I think that some people believe it's 40 to 50%, but we know that these are very arbitrary cutoffs. The data from the pooled analysis in PARAGON, in particular, do suggest that the patients who have evidence of some degree of left ventricular dysfunction seem to benefit from sacubitril/valsartan. Now, this is not a completely novel finding because we saw that in patients who received candesartan in the CHARM study and in patients who received spironolactone in the TOPCAT trial that the greatest benefit was observed in the patients in that middle range of ejection fraction, again, below what we would normally consider the normal range. Normal might be 55% or 55% in men and women.
And that gets me to the other thing that I think is really worth mentioning here, which is that we found that the range of benefits does vary by sex, so that women seem to derive greater benefit to a higher ejection fraction than men. We can see that here in figure 4, looking at these two curves that there really does appear to be a difference between men and women. Women overall derive greater benefit in the PARAGON study, it appeared than in men. So I think that the fact that there's biologic plausibility here that patients with cardiac function that is not normal seem to benefit from therapies that we know benefit patients with heart failure with reduced ejection fraction, that patients with ejection fraction that was in this middle range also do appear to benefit from sacubitril/valsartan as we think they did in other studies of other agents that we know work in patients with lower ejection fraction.
Dr Carolyn Lam: Indeed, Scott. You've just pointed out my favorite figure of all, that figure 4. You know how I feel about sex differences and pointing them out. I would love to ask for Biykem's thoughts on it.
But in the meantime, just to emphasize how important findings like these are because it makes us question the cutoffs that we use to define heart failure groups, makes us question is midrange more mildly reduced ejection fraction like we're also writing about. And I think really makes us question, for example, the 2016 ESC Guidelines that say that mid-range ejection fraction should be treated like preserved ejection fraction. Well, maybe this could be really game changing here in that we actually think now this group should be treated more like reduced ejection fraction. So, really, congrats on this incredible paper.
Biykem, what do you think of those sex differences? I have to point out, I love your editorial, which everyone should read.
Dr Biykem Bozkurt: It's very intriguing, very interesting point. The benefits from sacubitril/valsartan was interestingly similar for both sexes at lower EF levels. Women's benefit compared to men's benefit for low EF was comparable; they were not different. But women seem to confer a benefit at higher EF ranges and by this continuous analysis all the way up to the 50 to 60% range, which is very, very interesting. And as to what were the phenotypes of the women compared to men at that range, women were older, had more obesity, less CAD, and of course, at all ranges they usually tend to have a higher baseline EF.
And, interestingly, even though we may state that maybe women may have more systolic dysfunction at higher EF quantification ranges or may have a different phenotype than men for HFpEF, maybe a more clear or pure heart failure phenotype, heart failure with preserved EF phenotype than men. The interesting things were the NT-proBNP levels were lower for women, though the symptoms were a little bit higher, and the benefit seemed to be higher even though the KCCQ scores were not different. So, even though we did have lesser sort of filling pressures for women and perhaps other surrogates for improvement did not seem to differ, and also biological metabolites, such as urinary cyclic GMP to creatine ratios, were not different in women.
So, if we were to think of whether there were biological differences, whether there were differences in NT-proBNP levels or delta changes over time or the urinary cyclic GMP levels, they were not different in women versus men. So, we still have many other substrates for neprilysin. I mean there could be other substrates, such as adrenomedullin or bradykinin or substance P that may be differentially metabolized for women compared to men, and we don't have the data on those. But again, it's very interesting to see this upper scale of EF benefit being higher in women compared to men. So, we don't have any other either biological or other surrogate markers for benefit for women, either for the HFpEF or HFrEF being than different than men.
Dr Carolyn Lam: Biykem, I just love the way you so carefully dissected that, and it's so reflected in that editorial that you and Justin Ezekowitz wrote entitled Substance and Substrate. So I'm going to make sure all readers look for it. We could go on forever. I mean I just was struck, that figure 4, also is really similar if we look at what normally ejection fraction is for women versus men with increasing age. We also see that women are supposed to have higher ejection fractions as they age compared to men at any age. So it's just intriguing to me, but you're right. I think hypothesis generating.
Scott, I'm going to give you the last word.
Dr Scott Solomon: I'm pretty confident that there are biologic differences between men and women. I just don't necessarily know what they are with respect to heart failure, preserved ejection fraction, but I think we're going to be spending a lot of time and effort trying to sort this out. We're pretty confident that the finding of a weighing of benefit with ejection fraction is a real one and that the benefit in this middle range is an important one to pay attention to because I agree with what you said, Carolyn. If we had been thinking about heart failure with reduced ejection fraction as something that went up to a higher level 25 years ago, we would probably have treated a lot more patients with therapies that we now know to benefit patients with heart failure with reduced ejection fraction. So, I think this data helps us rethink how we parse up heart failure and hopefully, ultimately will lead to changes how we treat patients.
Dr Carolyn Lam: Well, listeners, you heard it right here on Circulation on the Run. Thank you so much, Scott and Biykem, for joining us, and don't forget to tune in again next week.
Dr Greg Hundley: This program is copyright The American Heart Association 2020.