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Circulation on the Run


Sep 26, 2022

This week, please join authors Hanna-Kaisa Nordenswan and Jukka Lehtonen, as well as Associate Editor Mark Link as they discuss the article "Incidence of Sudden Cardiac Death and Life-Threatening Arrhythmias in Clinically Manifest Cardiac Sarcoidosis With and Without Current Indications for an Implantable Cardioverter Defibrillator."

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, VCU Health in Richmond, Virginia.

Dr. Peder Myhre:

And I'm Dr. Peder Myhre, Social Media Editor in Circulation from Akershus University Hospital, and University of Oslo, Norway.

Dr. Carolyn Lam:

Oh, I am so excited about our feature paper today. It is about a condition that may not be as commonly encountered, but this paper can change clinical practice. It's about cardiac sarcoidosis and the indications for an ICD. Listen up. Very important stuff and discussion coming right up. But first, let's grab coffees and discuss the other papers in today's issues. Shall we?

Dr. Greg Hundley:

Right. So Carolyn, Peder, how about I go first? And so, both of you... we start with a really interesting, very practical study. It's somewhat unclear whether replacing an oral glucose tolerance test with just a hemoglobin A1C measurement for diagnosing diabetes is justified. And so these authors led by Adam Tabák, from University College of London in the United Kingdom, aimed to assess proportion of oral glucose tolerance tests, diagnosed diabetes cases that can be confirmed with hemoglobin A1C measures. And to examine whether individuals with oral glucose tolerance test diagnoses, but non-diagnostic hemoglobin and A1C are at higher risk of macro and microvascular disease. So the study included 5,773 men and women from the population based Whitehall II prospective of cohort study in the United Kingdom.

New oral glucose tolerance tests, diabetes cases diagnosed in clinical examinations between the years of 2002 and 2004. And again, in 2007 and 2009 were assessed for hemoglobin A1C confirmation of a value greater than 6.5% in these. And then again, so in those years, and then again, in subsequent clinical examinations in the periods of 2012 to 2013 and 2015 to 2016, now all participants were followed for major cardiovascular events via linkage to electronic health records until the year of 2017. And for incident chronic kidney disease by an estimated glomerular filtration blade of less than 60 mLs per minute per meter squared, until the last clinical examination.

Dr. Peder Myhre:

Thank you, Greg. That is such an important study with direct clinical implications. And I'm so curious to know what did they find?

Dr. Greg Hundley:

Right, Peder. Right, Carolyn. Carolyn's in the background, it's like a mind meld with Peder. She's going to keep pounding me with these same questions. Okay. So in this population based cohort study, with five yearly repeated oral glucose tolerance tests and hemoglobin A1C measurements, only 59.3% of the oral glucose tolerance tests diagnosed diabetes cases were confirmed by hemoglobin A1C at the same or a subsequent examination during 4.1 years of follow up. Incident oral glucose tolerance test diagnosed diabetes cases with hemoglobin A1C confirmation, and preexisting diabetes cases had similarly increased risks of cardiovascular disease and chronic kidney disease. While notably unconfirmed oral glucose tolerance test cases had a similar risk as the diabetes free population.

Dr. Peder Myhre:

Wow. That is really remarkable, Greg. Thank you for that summary. But can you please just give us, from this complicated paper, can you just give us some take-home points for the listeners.

Dr. Greg Hundley:

Right, Peder. So first, in this study, people with oral glucose tolerance tests diagnosed diabetes without diagnostic hemoglobin A1C have a risk of cardiovascular disease and chronic kidney disease, similar to the diabetes free population. And therefore, replacement of oral glucose tolerance tests with hemoglobin A1C based diagnoses appears justified. Second, there seems to be no need to consider oral glucose tolerance testing when hemoglobin A1C and fasting glucose levels are apparently inconclusive. Fasting glucose tests are needed only in exceptional circumstances where hemoglobin A1C results are felt to be unreliable. And then, finally, these findings lend confidence to widespread use of hemoglobin A1C for diagnosing diabetes in the vast majority of clinical settings.

Dr. Peder Myhre:

Wow. Greg, thank you so much. This was so helpful. Well, I'm going to move on to the second original research article. And that is from the DAPA-HF trial, that I know Carolyn has been quizzing you throughout the years about. So I'm not going to quiz you, but I'm just going to ask you. Did you know that SGLT-2 inhibitors increase hematocrit and that it has been identified as one of the key mediators of the clinical benefits on this class of drugs.

Dr. Greg Hundley:

So Peder, they're really interesting. And the second week of this you're popping out with these quizzes. I didn't do this to Carolyn. It was like a couple months. So anyway, but-

Dr. Carolyn Lam:

Way to go, Peder. Way to go.

Dr. Greg Hundley:

Yeah. Well, the good news is, I can just say yes. I did know that.

Dr. Peder Myhre:

That's nice. And in this paper, we're going to learn even more. Because the authors are taking this further by looking into the iron metabolism and assessing iron deficiency in the DAPA-HF trial. So just to remind you, although, you are familiar with it at this point, Greg, and of course, Carolyn, the DAPA-HF trial was large RCT testing efficacy and safety of the SGLT-2 inhibitor compared to placebo in patients with heart failure and a reduced ejection fraction. And in this post talk analysis, the authors examine the prevalence and consequences of iron deficiency and the effect of dapagliflozin on markers of iron metabolism. They also analyze the effect dapagliflozin on outcomes according to iron status at baseline.

Dr. Greg Hundley:

Oh, wow, Peder. So what did they find?

Dr. Peder Myhre:

So in total, 44% of patients in DAPA-HF were defined as iron deficient. And that was defined as having less than 100 nanogram per milliliter of ferritin or a key set of less than 20% and a ferritin level between 100 and 299 nanogram per milliliter. So the rate of the primary outcome was higher in patients with iron deficiency compared to those without. That was 16 versus 10 per 100% years. And the effect of dapagliflozin on the primary outcome was consistent in iron deficient compared to iron replace patients with a fever interaction of 4.59.

And similar findings were observed for cardiovascular death, heart failure hospitalizations and all-cause mortality. And finally, and very importantly, ferritin, T cell, and hepcidin were reduced with dapagliflozin versus placebo. So the authors conclude that iron deficiency was common in DAPA-HF. And associated with worse outcomes. Dapagliflozin, appeared to increase iron utilization, but improved outcomes, irrespective of iron status at baseline.

Dr. Greg Hundley:

Very nice, Peder. Wow. Just another important piece of information that we're learning about SGLT-2 inhibition. Well, Peder, my next paper comes from the world of preclinical science and it's from a group of authors led by Dr. Osamu Takeuchi from Kyoto University. Primary pulmonary arterial hypertension, Peder, is often characterized by obliterative pulmonary vascular remodeling, resulting in right heart failure. And although, the pathogenesis of pulmonary arterial hypertension is not fully understood. Inflammatory responses and cytokines have been shown to be associated with pulmonary arterial hypertension, particularly with connective tissue disease. So in this sense, Regnase-1 and RNAs, which regulates mRNAs in coding genes related to immune reactions was investigated in relationship to the pathogenesis of pulmonary hypertension.

Dr. Peder Myhre:

Wow, Greg. Pulmonary arterial, a hypertension and mRNA degradation of IL-6. So what did they find, Greg?

Dr. Greg Hundley:

Right, Peder. So these investigators examined the expression levels of Z3H12A in coding Regnase-1, in peripheral blood mononuclear cells from pulmonary hypertension patients classified under various types of pulmonary hypertension, searching for an association between the ZC3H12A expression and the clinical features associated with pulmonary hypertension. They then generated mice lacking Regnase-1 and myeloid cells, including alveolar macrophages and examined right ventricular systolic pressures, and histologic changes in the lung.

They found that Regnase-1 maintains lung innate immune homeostasis via the control of IL-6 and PDGF in alveolar macrophages, thereby, suppressing the development of pulmonary arterial hypertension in mice. And furthermore, the decreased expression of Regnase-1 in various types of pulmonary hypertension implied its involvement in pulmonary hypertension pathogenesis. And then, therefore, may serve as a disease biomarker as well as a therapeutic target for pulmonary hypertension. Very, very interesting work from the world of preclinical science. So how about we jump and see what else is in the mail bag?

Dr. Peder Myhre:

So we have From the Literature by Dr. Tracy Hampton, and this time we get three summaries from preclinical science papers published on their journals. First, there is a summary of a paper suggesting that circadian and pluripotency networks control longevity related genes, and that was published in cell metabolism. There is also a summary from a paper on the varied responses to a high fat diet using mouse models published in high science. And finally, there is a summary related to Brugada syndrome and how gene therapy is a potential future therapy. And that was published in scientific translational medicine. So Greg, what did you have in the mail bag?

Dr. Greg Hundley:

Sure. Well, Peder, I've got a research letter from Professor Fang entitled “Mitochondrial Stress Induces HRIEIF2A Pathway that's Protective for Cardiomyopathy.”

Dr. Peder Myhre:

And finally, we have clinical implications of basic research from Dr. Garry and colleagues entitled “Cardiac Xenotransplantation, the Clinical Impact of Science and Discovery.” So let's move on the future discussion, Carolyn.

Dr. Carolyn Lam:

Absolutely. Thank you for excellent summary, Greg and Peder. Now, let's go the feature discussion on cardiac sarcoidosis.

Dr. Greg Hundley:

You bet.

Dr. Carolyn Lam:

Wow. Today's feature discussion is on a rare, but very important topic. And it's that of cardiac sarcoidosis. And you have to listen up because today's paper could actually change practice. So I'm very pleased and grateful to have the authors of this paper. The corresponding author, Dr. Hanna-Kaisa Nordenswan and coauthor, Dr. Jukka Lehtonen both from Helsinki University Hospital. As well as our associate editor, Dr. Mark Link, from UT Southwestern to discuss this very important paper. Hannah-Kaisa if you don't mind, could you start by just telling us about your paper and what you found?

Dr. Hanna-Kaisa Nordenswan:

Thank you so much for inviting us to the podcast. So cardiac sarcoidosis predisposes to sudden cardiac death. But how well the current guidelines for implantable cardioverter-defibrillators in CS issued by the Heart Rhythm Society in 2014 and the American College of Cardiology, American Heart Association and Heart Rhythm Society, consortium guidelines from 2017, discriminate high from low risk of sudden cardiac death is unknown. And this is what we wanted to examine. So our study is a nationwide study, including 398 patients with cardiac sarcoidosis. All patients had clinical cardiac manifestations and a histological diagnosis of sarcoidosis.

The histological diagnosis was myocardial in nearly one half of the population. So patients with and without class 1 to 2A indications for an implantable cardioverting-defibrillator at presentation were identified from this population. The occurrence of fatal or aborted sudden cardiac death and sustained ventricular tachycardias in follow-up were recorded. We also noted ICD indications emerging first on, follow up.

Dr. Carolyn Lam:

Great. What did you find?

Dr. Hanna-Kaisa Nordenswan:

So, first of all, we found that by the current ICD guidelines, 85 to 100% of our patients had at least one strong to modest class 1 to 2a indication for an early ICD implementation. And we also found a 10%, five-year cumulative incidence of sudden cardiac death in our population of cardiac sarcoidosis patients. Further, we found that patients without an early indication for an ICD by the Heart Rhythm Society guidelines had nearly 5% cumulative risk of sudden cardiac death at five years. These patients further had a 53% cumulative risk of either developing an indication or suffering from a life-threatening ventricular arrhythmia at five years follow up. Finally, we also found that a diagnosis of cardiac sarcoidosis based on myocardial histology, IE definite CS. So definite cardiac sarcoidosis predicted twice higher combined five-year risk of sudden cardiac death and life-threatening ventricular arrhythmia than diagnosis based on extra cardiac histology, IE probable cardiac sarcoidosis.

Dr. Carolyn Lam:

Wow. Thank you so much, Hannah-Kaisa and congratulations on such impactful findings. 398 patients and if I read correctly, a cohort spanning 30 years. Jukka, could you tell us a little bit more on how these patients were identified? And I think this is important too, because it speaks to the generalizability of your findings.

Dr. Jukka Lehtonen:

Exactly. Yeah. So we have a very proactive approach to cardiac sarcoidosis. So basically, if I give you an example, so we screen all patients less than 60 years of age with MRI. And if the MRI shows that there's any signs of myocardial damage, we do endomyocardial biopsy. And then, if we do biopsy, once take 10 samples from the right ventricular septum. If that comes out negative, as it very often comes, then we do a PET study. And if there's an extra cardiac signal, then we do biopsy that side. So usually, it's lymph nodes very often. And that gives us a probable cardiac sarcoidosis.

So probable cardiac sarcoidosis is the terminology that's used in Heart Rhythm Society, 2014 guidelines. It has the same prognosis, basically, the definite cardiac sarcoidosis that's based on endomyocardial biopsy. So if the PET shows no signal outside the heart, we usually repeat the biopsy either right or left side, depending where there's most signal. And we can do that up to three times. So we have a very proactive approach. And that explains why we have so many patients.

So because you may end up taking 30 biopsy samples and you have one sample that's positive. So that explains why 5.3 million people can have such a huge number of sarcoid patients. We don't think that we are special. We just think that we are very active in biopsy area. And I know that this is something that differs in different places, and the different centers in the US have very different policies, and in Europe as well. So why I think this explains why we have such a large population and why they're all biopsy verified cases.

Dr. Carolyn Lam:

Thank you so much, Mark. I know that as editors we spotted immediately what a precious, valuable cohort in data we were looking at. Could you frame that for us? Take us behind the scenes a little bit on what you thought when this paper first crossed your desk.

Dr. Mark Link:

Yeah. This was a paper that caught our interest right away for a number of reasons. One, is the large number of sarcoid patients, nearly 400, that's one of the largest series that's ever been published. And two, is the systematic way in which sarcoid was approached. And what we found fascinating is that once you had a diagnosis of cardiac sarcoid, be it either probable or actual, there was a high risk of having ventricular arrhythmias. And this is something that in the guidelines, it's not so clear, because it's clear if the EF's less than 35%, you should get an ICD. But if your EF's greater than 35% by current guidelines, that's not a class 1 indication. So we thought this paper had the possibility to move guidelines and that perhaps we should think about an ICD and any patient that has diagnosis of cardiac sarcoid.

Dr. Carolyn Lam:

Wow. That's a brave postulation though. Exactly, as I said at the beginning, I think it may be practice changing. What do you think about that? Jukka and Hannah?

Dr. Jukka Lehtonen:

I think that's exactly what we have noticed that we have, most of the cardiac sarcoid patients are less than 50 years of age. So I think, the average age is 49 or something. And they're mostly females, so 70% are females. So it's pretty unique cardiac disease, that's more common in females than in males. And I think this population is benefiting tremendously from the ICD therapy, so that's something that we can see. It's not based on randomized data, it's follow up data, but these patients have lots of ICD events, events treated by an ICD. So we think that this is a major problem. Our previous papers have shown that the mortality in sarcoidosis is 90% is ventricle arrhythmia. So this conclusion fits with that previous findings as well.

Dr. Carolyn Lam:

Wow. Hannah has this impacted your personal clinical practice? I mean, do you now therefore think any patient, especially, if they've got confirmed cardiac sarcoidosis biopsy proven. Are you going to just, no matter what, regardless, anything else be more likely to put an ICD?

Dr. Hanna-Kaisa Nordenswan:

Yeah. Based on this study, we think that all cardiac sarcoidosis patients presenting with clinical cardiac manifestations and with histologically proven cardiac sarcoidosis should be considered for an ICD implantation. But with patients, with having non-definite cardiac sarcoidosis and without class 1 to 2A indications for an ICD in these patients, probably, the pros and cons of an ICD should be carefully discussed. Well, if an ICD is not implanted, at least repeated risk appraisal is needed regularly during follow up.

Dr. Carolyn Lam:

That's great comments. Mark, what do you think is going to be needed as future steps to get it to change practice? Or do you think this is it? Because, I mean, this is... the issue is, it's not easy to say let's just do a trial in cardiac sarcoidosis, right? Where are we going to find those patients and so on. What do you think, Mark?

Dr. Mark Link:

Yeah. That's a very good question. Because this isn't randomized trial data, and the strength of evidence is best with randomized trial data. And will we get a randomized trial in sarcoid? I doubt it. I really doubt it. So we're going to be left with registry data. And so where I would see this going is other registries coming out, showing their data. I think we do need confirmatory data from another large registry or two, and that's going to change practice, but are we there yet? I don't know. I don't know. Based on the lack of randomized trial data.

Dr. Carolyn Lam:

Thanks. If I could then for the last questions, if I could give it to the authors, what are your plans for next steps, if any. Maybe, Jukka, do you want to start first?

Dr. Jukka Lehtonen:

Well, I think cardiac sarcoidosis has lots of open questions. It has only open questions. I think the direction we are going is to go to the drug trial. So whether treatment of the inflammation by different agents would provide benefit in terms of arrhythmias and heart failure. So there's an idea that take patients with, for example, that's something that we haven't finalized yet, but take patients with normal ejection fraction, randomized them to cortisone and no cortisone and see how they do. Because we don't really know whether even corticosteroids actually make a huge difference.

I think we have more than 200 cardiac sarcoid patients under follow up in our hospital. And I can see that there are patients that have very good prognosis and no events whatsoever over many years or even decade. And then we have other patients that have lots of events, arrhythmias and develop heart failure. So I think we need trials that help us to distinguish those patients and also trials that help us select right medications for each group.

Dr. Carolyn Lam:

Thank you, Hannah?

Dr. Hanna-Kaisa Nordenswan:

Based on this particular study, we think that also the next study should preferably be a larger multicenter study that would focus on the prognostic factors in cardiac sarcoidosis. Perhaps, a risk score could be developed by using more detailed information of the presenting manifestations and ventricular function and imaging findings, cardiac magnetic resonance and positron emission tomography.

Dr. Mark Link:

Yeah. And we at the editorial staff thought this was important enough paper to have an editorial, to comment on its usefulness and way forward in dealing with cardiac sarcoid patients. And this editorial is written by Rick Patton and will accompany the printed issue.

Dr. Carolyn Lam:

Thanks. And so, you heard it, everyone pick up that editorial, pick up that paper. This is an important topic, and so grateful that it was published with us. Thank you once again to the authors. Thank you once again, Mark, for managing this paper. So lovely. And thank you, audience for joining us today from Greg and I, 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 of the American Heart Association, 2022. 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, please visit ahajournals.org.