This week's episode features author Philippe Gabriel Steg and editorialist Gregg Stone as they discuss the article "International Observational Analysis of Evolution and Outcomes of Chronic Stable Angina: The Multinational Observational CLARIFY Study."

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Dr. Carolyn Lam:

Welcome to Circulation the Run, your weekly podcast summary and backstage pass to the journal and its editors. We're your co-hosts, I'm Dr. Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore here with my other co-host, a little bird that you can hear I think in the background and then my real co-host, Greg.

Dr. Greg Hundley:

Thanks so much, Carolyn. Yes, I'm Dr. Greg Hundley. I'm not the bird this week. Associate editor, director of the Pauley Heart Center in Richmond, Virginia. Carolyn, so this week, our feature discussion is really going to be on the importance of stable angina and what that means prognostically. But before we get to that, how about we grab a cup of coffee, talk to our other bird friends and then we jump in and talk about the other papers in the issue. Would you like to go first?

Dr. Carolyn Lam:

Love it, Greg. Thank you so much. This first paper, very important question. We know that while the 99th percentile is the recommended diagnostic threshold for myocardial infarction, some guidelines also advocate the use of higher troponin thresholds to rule in myocardial infarction at presentation. It's still unclear whether the magnitude or change in troponin concentration can differentiate causes of myocardial injury and infarction in practice. And so today's paper is really important from Dr. Mills from the University Center for Cardiovascular Science Royal Infirmary of Edinburgh in the University of Edinburgh and colleagues.

Dr. Carolyn Lam:

What they did was a secondary analysis of the high stakes trial of more than 46,000 consecutive patients with suspected acute coronary syndrome. They evaluated the performance of the 99th percentile rule in threshold and thresholds of 64 ng/L and five times the upper reference limit for the diagnosis of type 1 myocardial infarction. They found that troponin concentrations at presentation have a low, positive predictive value for type 1 myocardial infarction and a threshold of 50 times the upper reference limit is required to achieve a positive predictive value of more than 70%. A change in troponin on serial testing only marginally improved positive predictive value for type 1 myocardial infarction over the presenting troponin alone.

Dr. Greg Hundley:

Interesting, Carolyn. Very important data. What's our take home message here.

Dr. Carolyn Lam:

Well, troponin concentrations at presentation are insufficient to distinguish type 1 myocardial infarction from other causes of myocardial injury or infarction and should not be used in isolation to guide management decisions in patients with suspected ACS. Consideration of other important clinical factors may be more helpful than any particular rule in threshold to guide initial triage and management.

Dr. Greg Hundley:

Wow, Carolyn, so really great new data and more data on the utility of these troponin concentrations.

Dr. Greg Hundley:

Well, my next paper comes from the world of preclinical science and it's from Professor Vladimir Kalinichenko from Cincinnati Children's Hospital Medical Center. Carolyn, as we know, pulmonary hypertension is a common complication in patients with alveolar capillary dysplasia with misalignment of pulmonary veins, a severe congenital disorder associated with mutations in the Foxf1 gene. Now, while the loss of alveolar microvasculature causes pulmonary hypertension in, and we're going to abbreviate this ACDMPV patients, it is unknown whether increasing neonatal lung angiogenesis could prevent pulmonary hypertension and right ventricular hypertrophy in these subjects.

Dr. Carolyn Lam:

Wow. Wow. Okay. Let's repeat that. ACDMPV stands for alveolar capillary dysplasia and misalignment of pulmonary veins. Really cool stuff. What did they find, Greg? This sounds like a first of its kind study.

Dr. Greg Hundley:

Right, Carolyn. Thanks. The Foxf1 wild type, S52 mice developed pulmonary hypertension and RV hypertrophy after birth. The severity of pulmonary hypertension in these mice directly correlated with mortality, low body weight, pulmonary artery muscularization and increased collagen deposition in the lung tissue. Second, increased fibrotic remodeling was found in the human ACDMPV lungs. Third, the mouse endothelial cells carrying the S52F Fox1 mutation were used to produce chimeras via blastocyst complementation and to demonstrate that the Foxf1 wild type S52F endothelial cells have a propensity to differentiate into pulmonary myofibroblasts. And then finally, intravascular delivery of nanoparticles carrying Stat3 copy DNA protected the Foxf1 wild type S52F mice from RV hypertrophy and pulmonary hypertension, improved their survival and decreased that fibrotic lung remodeling. Carolyn, nanoparticle therapies increasing neonatal pulmonary angiogenesis may be considered to prevent pulmonary hypertension in alveolar capillary dysplasia with misalignment of pulmonary veins.

Dr. Carolyn Lam:

Wow, thank you, Greg. Such incredibly hopeful papers here. The next paper identified a key role of a particular amino acid in cardiac aging.

Dr. Greg Hundley:

Ah, Carolyn, so you didn't ask me the quiz but I guess it's implied here. Okay, I give up. Which amino acid is it?

Dr. Carolyn Lam:

Spot on, Greg. Well, the answer is phenylalanine. This is an essential amino acid whose levels are regulated by the tetrahydrobiopterin or BH4 dependent rate limiting enzyme, phenylalanine hydroxylase and whose expression is physiologically restricted to the liver and the kidney. Well, co-corresponding authors Dr. Czibik and Derumeaux from Paris, France, hypothesized that phenylalanine plays a causal role in promoting cardiac senescence and dysfunction based on prior evidence from human metabolomics that shed light on a link between amino acids, aging and heart failure, as well as data showing that plasma levels of phenylalanine increase with age and inversely correlate with leukocyte telomere length. In addition, increased serum phenylalanine levels are associated with heart failure. Here, the authors tested their hypothesis in a series of elegant mouse experiments and showed for the first time that a decline in hepatic phenylalanine catabolism was a causal contributor to a rise in systemic levels, leading to cardiac ectopic phenylalanine hydroxylase activity and resultant cardiac aging.

Dr. Carolyn Lam:

They demonstrated that phenylalanine administration induced a remarkable premature cardiac deterioration in young mice, closely mimicking that of aged mice and leading to cellular senescence in vitro. They identified hepatic phenylalanine catabolism to decline with age in a p21 dependent manner, while demonstrating that p21 deficiency prevented age related cardiac dysfunction. Administration of phenylalanine hydroxylase cofactor BH4 or dietary phenylalanine restriction, both abrogated the age related rise in the plasma levels and reversed age associated cardiac alterations. This study really identifies phenylalanine and its hydroxylase modulation as a potential therapeutic strategy to promote cardiac health and prevent age related cardiac impairment. Amazing, isn't it?

Dr. Greg Hundley:

Yeah, Carolyn. Really interesting about phenylalanine and while it may impact cardiovascular health and the aging process.

Dr. Greg Hundley:

Well, I know we've got some other articles in this issue, so how about I'll go and dip into the mailbag first? The first is from Professors Wong and Finn and they're exchanging letters regarding the prior publication entitled, Microthrombi as a Major Cause of Cardiac Injury in COVID-19 and it's a pathologic study. There's a nice Research Letter from Dr. Zhu entitled, "Catheter Based Adrenal Ablation Remits Primary Aldosteronism: A Randomized Medication Control Trial." There's a Perspective piece from Dr. Stehlik entitled, "The Long and Winding Road to an Effective Left Ventricular Assist Device: The Demise of Medtronic's HVAD." And then finally a report from Dr. Mehta and colleagues, really Carolyn, thinking about clinicians' wellbeing and addressing global needs for improvements in the healthcare field. And it's a Joint Opinion representing the American College of Cardiology, the American Heart Association, the European Society of Cardiology and the World Heart Federation. Really a nice report on really addressing physician stress in the workplace.

Dr. Carolyn Lam:

Nice. Well, there's also an ECG Challenge by Dr. Shi entitled, "An Acutely Breathless Patient with Inferior St-Segment Elevation: A Diagnostic Trap." In Cardiology News, Bridget Kuehn describe studies detailing heart risks for firefighters. Wow, what an interesting issue, but let's go on now to the feature discussion shall we, Greg?

Dr. Greg Hundley:

You bet.

Dr. Greg Hundley:

Welcome listeners to our feature discussion. And today we have with us Dr. Gabriel Steg from Paris, France, Universite de Paris. And also Dr. Gregg Stone, an editorialist from Mount Sinai in New York. Welcome gentlemen. And Gabriel, we'll start with you first. Could you describe for us some of the background related to your study and what was the hypothesis that you wanted to test?

Dr. Gabriel Steg:

Thank you, Greg. As you know, there have been tremendous changes in cardiology over the past 25 years with the advent of effective anti-anginal therapy, with the advent of myocardial revascularization and the dramatic changes produced by widespread availability of percutaneous coronary intervention and finally the availability of evidence based secondary prevention therapies. And there has been really a sea change in the presentation and treatment, management and outcomes of patients with coronary artery disease. And when we started off, we asked ourselves, is angina pectoris really prognostic in patients with stable coronary artery disease? Is the symptom of angina really prognostic? That was the question we tried to address.

Dr. Greg Hundley:

And Gabriel, what was your study population and your study design?

Dr. Gabriel Steg:

It was a very simple descriptive design. We use a large international registry of patients with stable coronary artery disease called the CLARIFY registry, which enrolled almost 35,000 patients with stable coronary artery disease and followed them up for five years. Now, how was stable coronary artery disease defined? It was defined as any of the following conditions, a prior MI, more than three months before enrollment, a prior PCI or a CBG, angina pectoris was a demonstration of myocardial ischemia on noninvasive stress testing or finally the presence of a fixed stenosis of the coronary arteries on an angiogram. And you could get any of these criteria. Of course you could have more than one at the same time. And the design was to describe the anginal status at baseline and every year based on investigator reports, not a formal angina questionnaire, as there are several, including the Seattle angina questionnaire. We had a very simple assessment of angina and angina severity based on presence or absence and then Canadian class of angina.

Dr. Greg Hundley:

Did you follow these individuals too? Did they experience specific events?

Dr. Gabriel Steg:

Yes. We collected all the cardiovascular hospitalizations events, revascularizations. We followed the medications and we collected the biological results, although there was no core lab but we collected the results of the tests that were done. We essentially aimed was that registry to describe the population, their management and their outcomes over five years. And this is over 40 plus countries. And fortunately does not include any patient from the United States but has a substantial contribution from Canada and Mexico.

Dr. Greg Hundley:

Very nice. And so what did you find, Gabriel?

Dr. Gabriel Steg:

Well, the first observation is the prevalence of angina at baseline and it's 22%. We found that in a patient population selected for having stable coronary artery disease, approximately a fifth to a quarter will have anginal symptoms. I don't think that's a major surprise but what was a big surprise to us is that angina resolved very, very substantially, 40% of the patients who had angina at baseline had no longer angina by one year. And what was even more surprising is what caused the resolution of angina. And it was rarely changes in anginal medications, rarely revascularization. It was largely spontaneous. Almost 80% of the patients had spontaneous resolution of angina. And so, yes, it's been known that angina can regress but we did not expect that it would regress that often and that much spontaneously without intervention or need for increasing medications.

Dr. Gabriel Steg:

And the other aspect is then we looked at what happened for those patients who had angina resolution at one year and what were the subsequent outcomes? And we found they were indistinguishable from those who had no angina at baseline. And then we looked at those patients who had persistent angina at one year or occurrence of angina at one year, despite not having angina at baseline. And again, we found that having angina at one year was detrimental to the longterm prognosis. It's really good that you either not have angina or that your angina resolve. That's really important.

Dr. Greg Hundley:

Did you find any differences, Gabriel, between men and women?

Dr. Gabriel Steg:

No. We looked at a variety of subgroups. We looked by criteria for enrollment. We looked across geographic locales. We looked according to the presence or absence of diabetes and sex and other variables and there were really no major differences. The results were remarkably consistent.

Dr. Greg Hundley:

Very nice. Well listeners, one of the advantages of some of the publications that we pursue at Circulation is the ability to bring in an editorialist. And with us today, we have Dr. Gregg Stone from Mount Sinai in New York. And Gregg, we want to turn to you. How do we put the results of this study in perspective with other studies that have been involved in this sphere of research?

Dr. Gregg Stone:

Well, thank you, Greg. First off, I'd like to congratulate Gabriel and his colleagues for a tremendous study and thank you and Circulation for offering David Waters and I, the chance to provide our perspectives. I think this study raises a lot of important issues. Angina is kind of like the common cold to cardiologists. We're always dealing with it but it can be very difficult to diagnose. There's typical angina, atypical angina, anginal equivalent disease, non-anginal chest pain, et cetera. And we've learned in the last several years or decade that the etiology of angina can be very complex. It's not just epicardial coronary disease. There can be microvascular disease, macro or microvascular spasm and other causes. I think that we have to, when we're thinking of angina, we have to try to understand the mechanism and know whether or not it's really due to at least epicardial coronary artery disease, which is the type of disease that may respond to revascularization.

Dr. Gregg Stone:

In this regard, both David and I were struck with the fact that the CLARIFY even though a very large population, is a very mature population of patients with coronary disease, who I believe were diagnosed at least approximately seven years ago, most had undergone a prior revascularization therapy, about 50% ahead of myocardial infarct and the minority interestingly had inducible ischemia. We wondered is this real angina? Is this true angina that these patients are having? Because they've been effectively revascularized. In contrast, I was one of the co-principal investigators of the ISCHEMIA trial, which was a very different population because we took only with exercise induced moderate or severe ischemia. And while we excluded most patients with class three or four angina because we know those patients basically don't tolerate medical therapy without frequent crossovers. We found that in our trial, angina was more persistent and was substantially reduced by revascularization, by an interventional approach. Much more so than in the medical therapy arm. I think that it really does depend on the patient population and the likelihood of which the angina is due to true inducible ischemia that may respond to a revascularization approach.

Dr. Greg Hundley:

Very nice. And so Gabriel, want to turn back to you, what do you think is the next study that really needs to be performed in this space?

Dr. Gabriel Steg:

Well, I think it's really in line with Dr. Stone's comments. I think that what we need to do is to have a much more formal prospective assessment of a broader population of patients with angina using formalized questionnaire, such as the Seattle angina questionnaire, which allow a much better and thorough characterization of the presence, type and severity of symptoms and to look across the whole spectrum of patients with and without myocardial ischemia and look at the prognostic importance of the symptoms. I think that teasing out the relationship between the anginal symptoms, their severity, myocardial ischemia and outcomes is really critical to our interpretation of the series of recent trials, the last of which being ISCHEMIA, which have revolutionized our thinking regarding management of coronary artery disease. And we're still somewhat in the dark as to how to incorporate that information relative to the symptoms and outcomes of our patients. And I think we still have a lot of work to do in that respect.

Dr. Greg Hundley:

Very Good. And Gregg, do you have anything to add to that?

Dr. Gregg Stone:

Yeah. I would certainly echo Gabriel's comments. In addition, I think we have to think of angina as a collection of different diseases. And we have to do a better job at trying to understand the mechanisms underlying angina. First, we have to be able to determine whether it's really cardiac in origin versus non-cardiac. And then second, we have to understand again, whether it's coming from epicardial coronary disease, microvascular disease or other mechanisms. We've just been struck in even many of our simple stent studies, how often patients redevelop angina after treatment with no re-stenosis whatsoever, suggesting that many of them may have other etiologies of angina. I think these studies to me are very important because they really highlight, yes how much we've learned but how much more work there still is to do for us to be able to effectively diagnose and treat these patients.

Dr. Greg Hundley:

Well listeners, we want to thank both Dr. Gabriel Steg, the author of this paper and also Dr. Gregg Stone, who provided his editorial expertise, in bringing us information from these 32,000 plus individuals from the CLARIFY registry, of patients with stable coronary artery disease and helping us answer really two questions regarding the presence of angina. One, both that angina may resolve spontaneously and then second, persistent angina is associated with future cardiovascular events.

Dr. Greg Hundley:

Well, on behalf of Carolyn and myself, I want to thank our speakers and then also wish everyone a great week and we will catch you next week on the run.

Dr. Greg Hundley:

This program is copyright of the American Heart Association, 2021. The opinions expressed by speakers in this podcast are their own and not necessarily those of the editors or of the American Heart Association. For more, visit ahajournals.org.

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