Show notes
Please join author Ole Fröbert and Associate Editor Dharam Kumbhani as they discuss the article "Influenza Vaccination After Myocardial Infarction: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial." Dr. Carolyn Lam: Welcome to Circulation on 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 in Duke National University of Singapore. Dr. Greg Hundley: I'm Dr. Greg Hundley, associate editor, director of the Poly Heart Center at VCU health in Richmond, Virginia. Well, listeners, this week we've got a really hot feature topic pertaining to flu vaccines, which are coming in the US, North America, South America, coming up soon, and their relationship to myocardial infarction. But before we get to that feature discussion, let's grab a cup of coffee and jump in to some of the other articles in this issue. Oh, wait a minute. Our first article, we've got a co-author here. Carolyn, something about the VICTORIA trial, which you were a part of. Can you tell us a little bit about this? Dr. Carolyn Lam: I would love to, and first of all, I'm doing this on behalf of a big team, and I want to really, really call up first Dr. Paul Armstrong who's the senior author from University of Alberta. But let me tell you first about the VICTORIA study. VICTORIA evaluated vericiguat, a soluble guanylate cyclase stimulator, compared to placebo, in patients with heart failure with reduced ejection fraction with a recent worsening heart failure event and the primary result was actually a significant reduction in the primary composite outcome of cardiovascular death or heart failure hospitalization with vericiguat compared to placebo. Dr. Carolyn Lam: Now, interestingly though, in VICTORIA, we found that anemia occurred more often in patients treated with vericiguat at a rate of about 7.6% compared to placebo, which was 5.7%. Now, although earlier studies of another soluble guanylate cyclase stimulator like riociguat was found to be associated with anemia. The etiology really remains unknown. In the current paper, we explored the relationship between markers of anemia and vericiguat versus placebo in VICTORIA. We further explored the changes in hemoglobin and hematocrit over the course of the trial and their relationships with the primary composite outcome. Dr. Greg Hundley: Carolyn, this is such an important new study heart failure therapy for those with reduced ejection fraction, and again, an important topic related to anemia. What did they find? Dr. Carolyn Lam: Thanks, Greg. First, approximately a third of patients in VICTORIA had anemia at randomization, and this is using the standard sex-based definitions. With a lower hemoglobin indeed predicting a higher risk for cardiovascular death, heart failure hospitalization, all-cause mortality. As I had already mentioned, we found more anemia with vericiguat than with placebo. The interesting thing though is after 16 weeks, no further decline in hemoglobin occurred over the remaining and over 96 weeks of follow up, and the ratio of hemoglobin to hematocrit remained constant. Now, overall, the adverse event of anemia occurred in 7.1% of the patients. Dr. Carolyn Lam: Importantly, the lower hemoglobin was not related to the beneficial effect of vericiguat over placebo on the primary outcome. Now, I know all of that may be more descriptive and reassuring than really understanding the mechanism by which it occurred. Further mechanistic studies are certainly warranted to better understand the basis of the anemia development, and it's of principle importance because as you said, vericiguat I think it's going to be an important new medication that we can consider in high-risk patients with recent worsening heart failure with reduced ejection fraction. Dr. Greg Hundley: Thanks so much, Carolyn, especially the perspective of being an author on this particular study. Well, Carolyn, my next study is going to come to us from Dr. Zhao Wang from University of Texas Southwestern Medical Center, and it's really about the integrated stress response, and that's an evolutionary conserved process to cope with intracellular and extracellular disturbances. Myocardial infarction is a leading cause of death worldwide. Coronary artery perfusion is the most effective means to mitigate cardiac damage resulting from myocardial infarction. However, that can cause, as we know, additional reperfusion injury. This study aim to investigate the role of the integrated stress response in myocardial ischemia reperfusion injury. Dr. Carolyn Lam: Oh, very interesting. What were the results? Dr. Greg Hundley: Right, Carolyn. The authors found that the integrated stress response is activated by ischemia reperfusion injury in the heart, and the perk branch of the integrated stress response protects the heart from ischemia reperfusion injury through inhibition of protein synthesis. Also, Carolyn, mitochondrial complex proteins are selectively suppressed and oxidative stress is reduced by the integrated stress response. Carolyn, the takeaway is that this integrated stress response is cardioprotective against cardiac ischemia reperfusion injury. Perhaps pharmacological stimulation of the integrated stress response at reperfusion, well, that may reduce heart damage and improve cardiac outcomes after ischemia reperfusion injury. Dr. Carolyn Lam: Cool. Thanks, Greg. Well, I've got one more paper, and this deals with coronary microcircuitry dysfunction and acute rejection after heart transplantation. Co-corresponding authors, Doctors Lee and Choi from Heart Vascular Stroke Institute in Samsung Medical Center sought to evaluate the prognostic implications of coronary microcircuitry dysfunction assessed by the index of microcircuitry resistance or IMR for the risk of acute cellular rejection after heart transplantation. They did this by prospectively enrolling 154 heart transplant recipients who underwent scheduled coronary angiography and invasive coronary physiological assessment one month after transplantation. Dr. Greg Hundley: Very interesting, Carolyn. What did they find here? Dr. Carolyn Lam: IMR measured early after heart transplantation was significantly associated with the risk of acute cellular rejection, and an IMR above or at 15 was highly predictive for the recurrence of acute cellular rejection during two years of follow up following heart transplantation. Adding IMR to the prediction model with clinical variables significantly increase discriminant and reclassification ability for the risk of acute cellular rejection. In addition to surveillance endomyocardial biopsy, the implications are that early stratification using IMR could be a clinically useful tool to identify patients at higher risk of future acute cellular rejection after heart transplantation, and this is discussed in an editorial by Doctors Fearon and Valentine from Stanford University. Dr. Greg Hundley: Very nice, Carolyn. Dr. Carolyn Lam: Great. Greg, before we go to the exciting feature discussion, let's round it up by just a quick tour of what else there is in today's issue. There is an exchange of letters between Doctors Pappone Leor on atrial fibrillation as a cardiomyopathy, global rounds on United Kingdom by Dr. Cowie, an ECG challenge by Dr. Tsai on grouped beating following acute inferior myocardial infarction, and a research letter by Dr. Salem on electrocardiographic manifestations of immune checkpoint inhibitor myocarditis. Dr. Greg Hundley: Great, Carolyn. Well, I can't wait to get to this next feature discussion and learn a little bit more about the relationship between flu vaccines and future myocardial infarction. Dr. Carolyn Lam: Today's feature discussion was a really hot topic at the ESC 2021, and in fact, a simultaneous publication. It is about influenza vaccination after myocardial infarction, a very important topic and a very novel paper. We are so pleased to have the first and corresponding author, Dr. Ole Fröbert from Orebro University in Sweden to discuss this paper, as well as our associate editor, Dr. Dharam Kumbhani, from UT Southwestern. Welcome, gentlemen. Only if I could start with asking you to describe the rationale for why you did this study, and then perhaps quickly summarize the results. Dr. Ole Fröbert: Yeah, thank you so much, Carolyn. The background of the study was that during influenza epidemics, more people die from cardiovascular causes, and out in the literature, there are numerous observational studies suggesting a protective effect from influenza vaccination on cardiovascular events. There are also three smaller single-center randomized trials supporting these registered findings. Currently influenza vaccination carries a Class I, Level of Evidence B recommendation in both American and European secondary prevention guidelines, but uptake is low and vaccination timing is unclarified. Our aim was to determine whether influenza vaccination improves clinical outcomes in patients with a recent myocardial infarction or with high risk corona artery disease. Dr. Ole Fröbert: The study was international, multi-centers investigator initiated, double-blind randomized control trial, and we enrolled patients at 30 centers across eight countries in both the Northern and the Southern Hemisphere, Sweden, Denmark, Norway, Latvia, Scotland, Czech Republic, Bangladesh and Australia. We enrolled patients between October 2016 and March 2020. We had quite broad inclusion criteria. We included hospitalized patients with STEMI or non-STEMI, or high-risk stable patients over 75 years of age undergoing an angio or PCI. We excluded patients already vaccinated or intending to be vaccinated during the current season. We also included, of course, patients if they had allergy to X or influenza vaccine, if they had infection or if they were immunosuppressed or previously randomized in the trial. Dr. Ole Fröbert: Over these four years of inclusion, we enrolled a total of 2,571 participants. The primary outcome was a composite of all-cause death, MI and stent thrombosis. This outcome occurred in 67 participants assigned influenza vaccine and 91 assigned placebo corresponding to a reduction of the primary endpoint of 28% with a P value of 0.04. Also, rates of all-cause death and of cardiovascular death were reduced and both with a hazard ratio of 0.59 corresponding to a reduction of 41% in all-cause death and cardiovascular death. Based on these results, we think that this trial and what we know from previous smaller trials should be sufficient to establish influenza vaccination as a new standard of care as part of in-hospital treatment after an MI. Dr. Carolyn Lam: Heartfelt congratulations, Ole. What an elegant intervention in a very frankly challenging situation that the trial obviously carried on through COVID as well, multinational. May I just double check? Was it investigator-led? Because- Dr. Ole Fröbert: Yes, this was- Dr. Carolyn Lam: That's amazing. Dr. Ole Fröbert: ... an idea that just popped up, and then yeah, we did it, but it was seven years of work. Dr. Carolyn Lam: Wow. Hard work as I can just imagine. First, heartfelt congratulations. Very impactful results. Dharam, could I invite you to put those results in context and why we single this out? Dr. Dharam Kumbhani: Yeah. No, thank you, Carolyn. Ole, I want to amplify or recapitulate the amazement and wonder that Carolyn just articulated. I think this is a huge endeavor. It's a very important topic. It's "a fairly simple intervention." It's vaccination, and you've just really shown that even in the acute setting, that A, this is as feasible, B, it is safe, and three, it is effective. I think it's potentially ... Given the magnitude of influenza in the world, I think this has tremendous public health ramifications. I really want to congratulate you and your investigators for pursuing this important question and then just executing this, I'm sure despite multiple challenges over a long period of time. Dr. Ole Fröbert: Thank you very much. Dr. Dharam Kumbhani: Yeah, no. I guess you already alluded to the fact that this may influence guidelines. As you mentioned, it's a 1B. Maybe get your thoughts, I suppose this may move the needle towards becoming perhaps a little stronger on the recommendation front, both in the US and the European guidelines? Dr. Ole Fröbert: Yeah. I think what has been the challenge until now is that many places, of course, you commend patients to take a flu jab when treatment is over in the hospital. But then the responsibility is diffused. Who should take care of that? Is that up to the patient or the primary care physician? Who is in charge? One important finding of this study is, as you said, it's safe. There were no differences, adverse events between the two groups. It's safe and it could be given early. I think a take-home factor from the study is that it should be given at the hospital and it's a responsibility of the cardiologist. Dr. Dharam Kumbhani: Yeah, I really like that. Actually, I'm sure this would resonate across the board in the cardiology community. We've taken ownership for starting from statin and now SGLT-2 inhibitors, which kind of ... All of these medications have come from non-cardiology realms, so to say. But now we prescribe those medications. We know they have clear cardiovascular benefits. I suppose you could make a case to say we, the cardiology community, has to adopt this. The implementation gap that exists for a lot of these therapies, that also comes to us and for us to move that forward. It's thought provoking. I certainly felt very strongly after your study. I don't know how you feel about that. We should really be the ones driving this and help with more widespread immunization in these patients. Dr. Ole Fröbert: I think because not just this study, but also the previous studies and what we know from observational findings is that this is safe and it works. What we also saw in our study, and it has been indicated in previous meta analysis, is that the maximum effect is seen in the acute setting. It's the acute coronary syndrome patients, the patients we had in our study, that benefit the most. That's also a case for actually doing this in the hospital and not postponing it. Dr. Carolyn Lam: Wow. That's amazing. Ole, I do have one question. Just for clarification. You were careful to say that you did this during influenza seasons, right? Coming from my part of the world in Singapore where we don't really have influenza seasons, don't have any seasons, frankly, what would you think? What would you advise? Dr. Ole Fröbert: There is influenza seasons in all parts of the world, I'm sorry. Dr. Carolyn Lam: True. Dr. Ole Fröbert: For example, we had Bangladesh on board in our study. It's in the Northern Hemisphere, but influenza-wise, it's in the Southern, and their season is between May and September. But it's not as clearly defined as the Northern Hemisphere season. It's almost always in two waves during that season. One practical challenge with influenza vaccine is that it's produced for the seasons. It's difficult to say, "Yeah, we can just do it all year round," and also we didn't test that. I, of course, feel we should give it all year round, but it's not available, the vaccine. Perhaps it should be tested, but it is probably difficult to find funding for such a study. Dr. Carolyn Lam: Very fair, and thanks for the correction. It's true though. Singapore's on the Equator, so we don't have maybe weather seasons. But yeah, we do get vaccinated for both North and South. It's quite fascinating. But no…
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