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Circulation on the Run

Dec 3, 2018

Dr Carolyn Lam:                Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore.

                                                Our featured paper this week reports the five-year clinical outcomes and valve durability in the largest available cohort to date of consecutive high-risk patients undergoing transcatheter aortic valve replacement. You must listen up for this discussion, coming right up after these summaries.

                                                The first original paper describes a personalized risk assessment platform that promotes the implementation of precision medicine by helping us with the evaluation of a genomic variant of uncertain significance. A genomic variant of uncertain significance is a rare or novel variant for which disease pathogenicity has not been conclusively demonstrated or excluded and thus cannot be definitively annotated. These variants therefore pose critical challenges to the clinical interpretation and risk assessment. New methods are therefore urgently needed to better characterize their pathogenicity.

                                                Co-first authors, Dr Ma, Zhang, and Itzhaki, corresponding author Dr Wu from Stanford University School of Medicine and colleagues recruited a healthy, asymptomatic individual lacking cardiac disease clinical history and carrying hypertrophic cardiomyopathy associated genetic variant in the sarcomeric gene, MYL3, which has been reported by ClinVar database to be likely pathogenic.

                                                Human-induced pluripotent stem cells or IPSCs were derived from the heterozygous carrier, and their genome was edited using CRISPR/Cas9 genome editing to generate karyo-specific IPSCs. Extensive essays, including measurements of gene expression, sarcomere structure, cell size, contractility, action potentials, and calcium handling were performed on the isogenic IPSC-derived cardiomyocytes, and together, the platform was shown to elucidate both benign and pathogenic hypertrophic cardiomyopathy-functional phenotypes.

                                                Thus, this paper demonstrates for the first time the unique potential of combining IPSC-based disease modeling and CRISPR/Cas9 genome editing technology as a personalized risk assessment platform for determining the pathogenicity of a variant of unknown significance for hypertrophic cardiomyopathy in a patient-specific manner.

                                                Transcatheter aortic valve replacement is increasingly being used for the treatment of severe aortic valve stenosis in patients at intermediate risk for surgical aortic valve replacement. The next paper provides real world data comparing indications and clinical outcomes of patients at intermediate surgical risk undergoing isolated transcatheter vs. surgical aortic valve replacement.

                                                Co-first and corresponding others, Dr Werner and Zahn from Clinical Ludwigshafen in Germany compared clinical characteristics and outcomes of more than 7,600 patients with intermediate surgical risk who underwent isolated transcatheter or conventional surgical aortic valve replacement within the prospective all-comers, German aortic valve registry between 2012 and 2014.

                                                Multi-variable analyses reveal that factors that were associated with performing transcatheter instead of surgical aortic valve replacement included advanced age, coronary artery disease, New York Heart Association class three or four, pulmonary hypertension, prior cardiac decompensation, and elective procedure, arterial occlusive disease, no diabetes mellitus, and a smaller aortic valve area.

                                                Unadjusted in-hospital mortality rates were equal for transcatheter and surgical aortic valve replacement, whereas unadjusted one-year mortality was significantly higher in patients with transcatheter aortic valve replacement. After propensity score matching, the difference in one-year mortality was no longer significant. Thus, this large registry analysis suggests that both transcatheter and surgical aortic valve replacement are reasonable treatment options in a real world population with aortic stenosis and intermediate surgical risk.

                                                The next paper demonstrates a key role of vascular endothelial growth factor receptor 1 in hemorrhagic telangiectasia type 2. Now, this is an inherited genetic disorder where haplo-insufficiency of the activin receptor-like kinase 1 gene, ACVRL1, results in blood vessels that are prone to respond to angiogenic stimuli, leading to the development of telangiectatic lesions that can bleed.

                                                First author, Dr Thalgott, corresponding author, Dr Lebrin from Leiden University Medical Center and colleagues used ACVRL mutant mice and found that vascular endothelial growth factor, or VEGF receptor 1 levels were reduced, causing increased VEGF receptor 2 signaling that promoted sprouting angiogenesis, correcting the abnormal VEGF gradient, by expressing membranal-soluble VEGF receptor 1 in embryonic stem cells or blocking VEGF receptor 2 with antibodies in mutant mice, normalized the phenotype both in vitro and in vivo.

                                                Importantly, VEGF receptor 1 was reduced in the blood and skin blood vessels of patients with hemorrhagic telangiectasia type 2 compared with H match controls, demonstrating an important role of VEGF receptor 1 in these patients and explaining why their blood vessels might respond abnormally to angiogenic signals. These findings support the use of anti-VEGF therapy in hemorrhagic telangiectasia type 2.

                                                The next study suggests that hydroxychloroquine could be repurposed to reduce the risk of rheumatic heart disease following acute rheumatic fever. First author, Dr Kim, corresponding author, Dr Wicks from Walter and Eliza Hall Institute of Medical Research and University of Melbourne and their colleagues analyzed the immune response to group A streptococcus in peripheral blood mononuclear cells from an Australian Aboriginal acute rheumatic fever cohort by a combination of multiplex cytokine array, flow cytometric analysis, and global gene expression analysis by RNA sequencing.

                                                They then tested the widely used immunomodulatory drug, hydroxychloroquine for its effects on this response. They found that group A streptococcus activated persistent IL-1 beta production and selective expansion of a specific group of T helper 1 cells that produce GMCSF. Furthermore, hydroxychloroquine limited the expansion of these group A streptococcus-activated, GMCSF-producing T helper cells in vitro.

                                                Gene transcriptional profiling of peripheral blood mononuclear cells from patients with acute rheumatic fever showed dynamic changes at different stages of disease. Given the safety profile of hydroxychloroquine and its clinical pedigree in treating autoimmune diseases such as rheumatoid arthritis where GMCSF plays a pivotal role, the authors therefore proposed that hydroxychloroquine could be repurposed to reduce the risk of rheumatic heart fever following acute rheumatic fever.

                                                The next paper identifies a new anchoring B genetic variant in unrelated Han Chinese probands with ventricular tachycardia. In this paper from co-first authors, Dr Zhu, Wang and Hu, co-corresponding authors, Dr Hong from Second Affiliated Hospital of Nanjing University, Dr Mohler from Ohio State University Wexner Medical Center and colleagues, the authors identified the first anchoring B variant, Q1283H, localized to the ZU5C region in a proband with recurrent ventricular tachycardia.

                                                Knocking mice with this variant showed an increased susceptibility to arrhythmias associated with abnormal calcium dynamics. The variant was associated with loss of protein phosphatase 2A activity, increased phosphorylation of ryanodine receptor, exaggerated delayed after depolarization-mediated trigger activity, and arrhythmogenesis. Furthermore, the administration of metoprolol or flecainide decreased the incidence of stress-induced ventricular arrhythmias, representing potential therapies for anchoring B variant-associated arrhythmias.

                                                Does variability in metabolic parameters affect health outcomes? First author, Dr Kim, corresponding author, Dr Lee from Seoul Saint Mary's Hospital College of Medicine and Catholic University of Korea and their colleagues used nationally representative data from the Korean National Health Insurance system, consisting of more than 6.7 million people who are free of diabetes, hypertension, or dyslipidemia and who underwent three or more health examinations from 2005 to 2012 and were followed to the end of 2015.

                                                Variability and fasting blood glucose and total cholesterol, systolic blood pressure and body mass index was measured using the coefficient of variation, standard of deviation, variability independent of the mean, and average real variability. They found that a high variability in fasting glucose and cholesterol, systolic blood pressure and body mass index was associated with a higher risk for all-cause mortality, myocardial infarction, and stroke. Variabilities in several metabolic parameters had additive associations with the risk of mortality and cardiovascular outcomes in the general population.

                                                These findings suggest that treatment strategies to reduce fluctuations in metabolic parameters may be considered another goal to prevent adverse health outcomes.

                                                How much exercise over a lifetime is necessary to preserve efficient ventricular arterial coupling? First author Dr Hieda, corresponding author Dr Levine from Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center and colleagues studied 102 seniors and grouped them based on their 25 years of exercise training history. The dynamic Starling mechanism was estimated by transfer function gain between beat-by-beat changes in diastolic pulmonary artery pressure and stroke volume index.

                                                They found that there was a graded dose-dependent improvement in ventricular arterial coupling with increasing amounts of lifelong regular exercise in healthy older individuals. Their data suggested that the optimal does of lifelong endurance exercise to preserve ventricular arterial coupling with age appeared to be at least four to five sessions per week. The sufficient lifelong endurance exercise was effective for maintaining the normal dynamic Starling mechanism, left ventricular compliance, and arterial compliance with aging, all of which may lead to favorable effect on cardiovascular stiffness or function.

                                                And that brings us to the end of our summaries this week. Now, for our feature discussion.

                                                Transcatheter aortic valve replacement is taking over the interventional world. It's really rapidly growing, and we're increasingly using it for the treatment of aortic stenosis. It was initially used for inoperable and high-risk patients but now is indicated even in the treatment of intermediate-risk patient, and even low-risk patients are being enrolled into current trials.

                                                So, with TAVR being used for low- and intermediate-risk patients, the longer-term results of this treatment involved your abilities becoming more and more important. Well, gratefully, we have today's feature paper, and it describes the five-year clinical outcomes and valve durability of the FRANCE-2 Registry.

                                                I'm so pleased to have with us the corresponding author, Dr Martine Gilard from University Hospital of Brest in France, we have our editorialist, Dr Anita Asgar from Montreal Heart Institute, and we have our associate editor, Dr Dharam Kumbhani from UT Southwestern.

                                                Martine, congratulations on this largest cohort of high-risk patients and long-term outcomes. Could you please tell us what you found?

Dr Martine Gilard:            Yes, and I'll just quote, actually, to have a follow-up of five years. We have 1,200 patients arrive at five years after rotation of TAVI. Each patient was a high-risk patient because it was at the beginning of each treatment, and in this time, it's only the high-risk patient was implanted with TAVI, and actually, we can follow this 1,200 patients, 50% of these patients of these patients have an echography because when we analyze these patients, we have an echography at five years, and the patients who have not echography at five years, the only difference is the age.

                                                It's very old patient. It's very difficult to make this echography on this patient to come back in our center, so it's why there is not all the patient who have an echography at five years.

                                                But our patients who have an echography, we can see that it's a very, very good result at five years. There is always the same area, just after before, of the valve. There is the same gradient. There is not a sign of deterioration.

                                                As you know, we have some guidelines published last year about how we asked to define deterioration of the valve, surgical or TAVI, and if we apply this new recommendation, we saw that in this largest cohort, at five years, there is only 13% of patient who have some sign of deterioration, and of these patients, we never need to make another valve in valve because the deterioration was not so important, and patient leave with this valve like that. There is no necessity to make a new valve in valve, so at five years of this very high-risk patient treated by TAVI, there is no necessity to implant a second valve because the valve deterioration. It's a very, very important message.

Dr Carolyn Lam:                Thank you, Martine. Indeed, an important message. And Anita, you wrote a beautiful editorial about it. First, could I ask you to frame the issue? I mean, is there any reason we would expect the durability to be any different from a surgical replacement?

Dr Anita Asgar:                  I think that's a great question, Carolyn, and I congratulate again Martine and her team for doing a fantastic job to add some very important results to the clinical literature on TAVI. Five years is relatively early to see structural valve deterioration, so in a sense, it's not surprising, and we would consider this sort of medium-term follow-up rather than really long-term durability, but very reassuring that in a high-risk population of patients, that TAVR performs very well in this population of patients and as mentioned, is very low to the dynamic structural valve deterioration.

                                                One question I have for Martine is, as you mentioned, there was only about 12% that had some evidence of structural valve deterioration hemodynamically, but this didn't result in another procedure, and I wonder if you could explain a little bit about that, whether it's the hemodynamic dynamic value, and yet there's a clinical indication for re-intervention. How do you incorporate the two?

Dr Martine Gilard:            It's actually hemodynamic deterioration, there is some form of regurgitation. However, there is no need or clinical indication to make another intervention. So, if you compare this research to the bioprostheses surgical paths, the only one who have, at five years, no need to make a re-intervention appearing rotated, which is a valve, a surgical valve we have a longer bioprostheses surgical path.

                                                So, if we compare this best bioprostheses surgical valve, we have sustained results at five years. At five years, we have no need to make a re-intervention because the deterioration was not so important or as needed for clinical evidence as a need to make a new intervention.

Dr Anita Asgar:                  So, there were some increased rates of heart failure in those patients with structural valve deterioration in your paper, and I know that in the paper you did mention that this is not an adjudicated outcome, and there wasn't a VARC definition for heart failure, but what's your interpretation of increasing heart failure events in these patients with structural valve deterioration?

Dr Martine Gilard:            We have no real definition about that. We know that there is another registry. We say that there is an increasing of heart failure, and during the follow-up, and the result of this heart failure increase in mortality. There is an increasing of heart failure, but the number of these patients, there is more. So I don't know if this due to because patient is a high-risk patient, or it's because of the TAVI, but it's very difficult actually to have a real explanation about that.

Dr Carolyn Lam:                Thanks, Anita and Martin. Dharam, could you share some of the thoughts and the discussions that were going on behind the scenes with the editors when we saw this paper?

Dr Dharam Kumbhani:   Professor Gilard, this was a really excellent paper. We really appreciated you sending it to us, and I think for us, the fact that this was a very large cohort, the largest published cohort that has gotten to five years in a TAVR population, in a multicenter study, and having very good follow-up up to five years, with these patients is always this competing hazard that you want to know what the valve is doing at five years from an echocardiographic and hemodynamic perspective, but there's such a high competing hazard of death, just given the population that you're enrolling, and still, you had one of the largest echo follow-ups on these patients, so we want to congratulate you on the study and really a monumental endeavor, and so really great, great work there.

                                                And I think this is, exactly some of the questions that I think we had and I'm sure that the audience would have as well, I guess the one other question I have, and it's not really a question about your paper. So the median Euro score is 21 in this study, approximately 21, so that's obviously gonna, consistent with the patients that are being enrolled at that time between 2007 and 2012, which were predominantly high-risk and inoperable patients. Can you talk to us a little bit about the landscape of, how is TAVR practice in France as a society or from the regulatory standpoint, what are the benchmarks that you have achieve as you move towards low-risk now? Because intermediate-risk, I'm assuming is a [inaudible 00:20:16], so could you talk to us a little bit about the landscape there?

Dr Martine Gilard:            Yes. In France, it's difficult because we have the authority to follow, not immediately, the ESC recommendations, so actually in France, we are allowed to implant only patients with high risk, patients with complication of surgery, and actually just since one year, patients with automatic risk, but we have no authorization to implant patient with low risk.

                                                However, the most important fact is the heart team, and if they write. Because we need to have something written, and if they write, if they explain that it's necessary to implant a patient at low risk because of some point while not including the risk score or it's very difficult to explain, for example, frailty or something, we can implant a patient with low risk.

                                                But normally actually, it is only for complication or high risk and for intermediate risk like the recommendation of the ESC.

                                                So the rate of implantation in France increased because we implant only 2,000 people per year, but actually, in 2017, we have implanted 10,200 patient, and this year, we think that we implant 12,800 patients, so as the number of patients increase, the number of patients who have a very high risk decrease because there is a futile indication, and we have a lot of futile indication, so we doesn't implant patient while too high-risk, and we select the most majority of patient implanted in France was high-risk but also intermediate-risk.

Dr Dharam Kumbhani:   So, you think you're implanting more intermediate, like that is a bigger population that is getting TAVIs right now in France?

Dr Martine Gilard:            Yes, exactly.

Dr Carolyn Lam:                How about perspectives from Montreal? What do you think the implications of this findings from today's paper in relation to the types of patients that you might perform this in now?

Dr Anita Asgar:                  For us, this is exceptionally reassuring, and as Martine has said, I mean, we have transitioned as well away from that very inoperable cohort C type of patient to more your higher-risk patient or intermediate, and to be honest, everyone over the age of 80 in Canada essentially is getting a TAVR.

Dr Carolyn Lam:                Oh, wow.

Dr Anita Asgar:                  Because regardless of their risk, and we've been very aggressive with that because trying to get patients back to an appropriate quality of life is very important, and to seeing this very reassuring data is telling us that, as she has already mentioned, we have reached the standard, at least in midterm follow-up as the gold standard of surgical valve replacement, and so structural valve deterioration is not as big a concern.

                                                I think we still however need longer-term data when we're looking at lower-risk patients, and lower-risk patients, let's remember, are not 60-year-olds. They're the 75-year-old, perhaps. But we're still gonna need some more data, but it's very reassuring, and patients are asking for it and are really advocating on their behalf to have a less invasive approach, and I think we can say now with more certainty that we know after five years, your chance of structural valve deterioration is actually quite low, and so I think that's very helpful from our point of view.

Dr Carolyn Lam:                I love that, Anita, and it's so consistent with the title of your editorial, "Closing in on the Finish Line". Love it, love it, and recommend all listeners pick it up and have a good read. Dharam, I want to leave the last words to you. What do you think are the implications of this paper?

Dr Dharam Kumbhani:   Well, I think that, as Anita said, this is very encouraging results that, in this kind of extreme and high-risk patient cohort, that there appear to be no medium- to long-term signals of structural valve degeneration, that the biggest hazard from this procedure is all upfront, and after that, it's pretty much, it's as we have seen with surgery, that after that, the actuarial rates come back to what you would expect.

                                                If they didn't have aortic stenosis and then they would die from whatever causes they had. Now obviously, that wasn't tested, but it seems like looking at the curves, that that seems like what's going on, so I think they've done a great service to our TAVR community in terms of showing us these results in very large, multicenter cohorts from France.

Dr Carolyn Lam:                Thank you so much for joining us today. Thank you, listeners. You've been listening to Circulation on the Run. Don't forget to tune in again next week.

                                                This program is copyright American Heart Association, 2018.