Aug 12, 2019
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 cohosts. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
Dr Greg Hundley: And I'm Greg Hundley, associate editor from the Poly Heart Center at VCU health in Richmond, Virginia. Carolyn, oh, this is going to be an exciting featured article today, and we're going to discuss the combination of agents or their administration et al that are best suited for managing both anticoagulation and antiplatelet therapy and those with coronary disease, peripheral arterial disease and heart failure. And, we'll speak with Dr Kelley Branch from the University of Washington.
Dr Carolyn Lam: And me!
Dr Greg Hundley: Yes. How am I going to interview you? And, we'll discuss the utility of Rivaroxaban with or without aspirin in patients with heart failure or peripheral arterial disease from the compass trial.
Dr Carolyn Lam: Well, I'm not going to let you get there until I tell you about this first basic paper I've chosen because it focuses on the unfolded protein response.
Dr Greg Hundley: What's that?
Dr Carolyn Lam: Well, Greg, I was really hoping you'd ask. The unfolded protein response is a cellular adaptive process to cope with protein folding stress. Now, approximately 40% of human proteins are predicted to be either transmembrane or secretory. The synthesis, the folding, the cellular transportation and location of these proteins rely on proper functioning of this secretory pathway. Numerous studies have established that the unfolded protein response plays versatile roles during development and under physiologic and pathophysiologic conditions. However, the role of this unfolded protein response in the regulation of cardiomyocyte growth is unclear.
Dr Greg Hundley: That's fantastic, Carolyn. I've already learned something here. So, what did this paper show?
Dr Carolyn Lam: This is from Dr Wang and colleagues from UT Southwestern, and basically, they use both gain and loss of function approaches to genetically manipulate spliced X-box binding protein one or XBP1, which is the most conserved signaling branch of the unfolded protein response in the heart. In addition, primary cardiomyocyte cultures were employed to address the role of XBP1S in cell growth in a cell autonomous manner. They found that XBP1S expression was reduced in both human and Rhode and cardiac tissues with heart failure deficiency of XBP1S lead to decompensation and exacerbation of heart failure progression under pressure overload. On the other hand, cardiac restricted over expression of XBP1S prevented the development of cardiac dysfunction. Mechanistically, they found that XBP1S stimulated adaptive cardiac growth, your activation of mechanistic target of rapamycin or MTOR signaling which is mediated via the FK-506 binding protein 11, which is a novel transcriptional target of XBP1S. So in conclusion, this study really showed a critical role of the XBP1S FKB or FK-506 binding protein 11 and MTOR axis in coupling the unfolded protein response and cardiac cell growth regulation.
Dr Greg Hundley: Boy Carolyn, you explained that so well, and I learned a lot from that. I hope I can do as well with this next article from Professor Johann Backs from the University of Heidelberg. Now paradoxically, some glucose lowering drugs have been shown to worsen heart failure, raising the question of how glucose mediates protective versus detrimental cardiac signaling, and this study from his group focused on one of the class two histone deacetylases or HDAC's namely HDAC-4, which functions as an important epigenetic regulator by responding to upstream stress signals, and linking them to downstream gene regulatory programs involved in among other things, metabolic regulation.
Dr Carolyn Lam: Very interesting. So what did they find?
Dr Greg Hundley: What they found is that HDAC4 acts as an important maintenance factor of cardiac function in diabetes and O-glycine-N0acetylglucosamine of HDAC4 at searing 642 induces the production of cardio-protective HDAC F-end terminal fragment and attenuates cardio detrimental Cam kinase two mediated phosphorylation of HDAC4 at searing 632. Vice versa, Cam kinase two mediated phosphorylation of HDAC4 at searing 632 attenuates HDAC-4 n terminal production. Thus, these findings lay the ground for the development of novel therapeutic strategies for diabetic patients with heart failure by inhibiting Cam kinase phosphorylation at CIHR 632 or enhancing o-glycine and escalation at searing 642.
Dr Carolyn Lam: Fascinating, Greg. Well, my next paper is a subgroup analysis of EUCLID and is the first to assess acute limb ischemia in the context of a large-scale clinical trial studying a primary peripheral artery disease population.
Dr Greg Hundley: So Carolyn, reminded us what was the EUCLID trial.
Dr Carolyn Lam: Okay, so EUCLID stands for Examining Use of Ticagrelor in Peripheral Artery Disease, and this was a randomized clinical trial that included acute limb ischemia as an adjudicated outcome in a primary peripheral artery disease population randomized to ticagrelor versus clopidogrel. Now in EUCLID ticagrelor was not superior to Clopidogrel for the prevention of cardiovascular events in patients with stable peripheral artery disease. However, a EUCLID subgroup analysis of patients with and without prior limb revascularization demonstrated significantly higher risk for acute limb ischemia hospitalization in patients with prior low extremity revascularization.
Dr Greg Hundley: So Carolyn, that's interesting. So, what did they find related in this study that focused on the acute limb ischemia?
Dr Carolyn Lam: Right. So, today's paper is from Dr Hess and colleagues at University of Colorado School of Medicine and CPC, clinical research in Aurora, Colorado. And, they found that acute limb ischemia occurred in 1.7% of almost 13,900 randomized patients with a median time to hospitalization for acute limb Ischemia of 320 days after randomization. In this population, prior lower extremity revascularization, atrial fibrillation and lower ankle brachial index identified patients at higher risk for acute limb ischemia. Hospitalization for acute limb ischemia was associated with subsequent cardiovascular and limb ischemic events. So, the take home message is providers should monitor for signs and symptoms of acute limb ischemia in patients with stable symptomatic peripheral artery disease, particularly those with prior lower extremity revascularization, atrial fibrillation, and lower ankle brachial index.
Dr Greg Hundley: That's very instructive, Carolyn. Fantastic message. So, I'm going to ask you if you could select one lipid biomarker to forecast future adverse cardiovascular events, which would you select? Total cholesterol, HTLC, non-HTLC, direct and calculated LDLC, APO-A1, or APO-B?
Dr Carolyn Lam: Well, I'm traditional. I would have chosen LDL.
Dr Greg Hundley: Okay. Well, the authors of this study led by Dr Paul Welsh at the University of Glasgow attempted to answer this question by studying participants from the UK Biobank without baseline cardiovascular disease and not taking statins with relevant lipid measurements. They had 346,686 participants. An incident fatal or nonfatal cardiovascular event occurred in 6,200 participants of which 1,656 were fatal, and they occurred over a median time of 8.9 years. So, the associations of non-fasting lipid measurements, total cholesterol, HDLC, non HDLC, direct and calculated LDLC, APO-a1, and APO-B with cardiovascular disease were compared using Cox models, adjusting for classical risk factors and predictive utility was determined by the C-index and net reclassification index. Also, prediction was tested in 68,649 participants taking a statin with or without baseline cardiovascular disease, and that group experienced 3,515 cardiovascular events.
Dr Carolyn Lam: Okay, so drum roll. What did they find?
Dr Greg Hundley: So, measurement of total cholesterol and HDLC in the non-fasted state is sufficient or was sufficient to capture the lipid associated risk in the cardiovascular disease prediction with no meaningful improvement from addition of APO lipoproteins, direct or calculated LDLC. And, similar findings were reproduced in those taking a statin at baseline.
As such, the authors feel like calls for widespread use of APO lipoproteins are not warranted given the negligible difference in risk prediction beyond total cholesterol in HDLC. And, direct LDLC is also not required for risk prediction. Non HDLC is a cheaper or equivalent predictor of risk on and off statins without the requirement of one of us being fasting. This is an excellent article for our listeners to review or download.
Dr Carolyn Lam: Wow, that is so cool. So, from one excellent paper to another excellent paper in our feature discussion. Let's go, shall we?
Dr Greg Hundley: Welcome everyone to discussion of our featured article. We have Dr Kelley Branch from the University of Washington and our own Carolyn Lam, and they're going to be discussing the compass trial. So Kelley, could you tell us a little bit about the rationale for compass as opposed to the previously published commander study?
Dr Kelley Branch: So, in order to understand compass and compare it to commanders, we're going to have to go back a little bit in time here. And recall, you know well over 20 years ago that when we used anticoagulants in coronary artery disease, that was actually shown to be more beneficial than aspirin alone, but because of the excess bleeding risk, warfarin or vitamin K antagonists not used, and aspirin won. Fast forward a number of years, and now we have the non-vitamin K anticoagulants, and the was potentially that we could find the goldilocks, if you will, the good balance of benefit as well as less bleeding maybe used to these new agents. So, the compass trial was really born from an atlas ACS one and Atlas ACS two, which found that a low dose of, in this case, Rivaroxaban 2.5 milligrams VAB as well as five milligrams VAB were shown to be beneficial in patients after acute coronary syndrome.
And then, it was thought what happens if we treat these patients with now chronic coronary disease as well as arterial disease? And from this 27,000 patients, 47,395 patients were tested, and our study very specifically looked at patients with a baseline or a history of heart failure when they answered compass. Compass were shown to be beneficial with specifically the use of aspirin plus Rivaroxaban, 2.5 milligrams BAD. And, our idea was to test this in patients with this baseline or history of heart failure. Now, this is in real contradistinction to what the commander tried to do. And the reason why encompass, we actually excluded patients with severe heart failure. This was defined as a New York Heart Association class three or four or an ejection fraction less than 30%. Now if you looked at patients with commander, these patients had ejection fraction less than 40%. That was a criteria to get in. And of course, these patients had to have a recent hospitalization for heart failure. So, these are very different patient populations. Well, both of them, yes, they did have coronary artery disease, but really very different patient populations.
Dr Greg Hundley: Very good. So Kelley, tell us specifically, what were your treatment group assignments and the doses and the outcomes that you were going to follow, and then lead us into what did you find? What were the outcomes of your study?
Dr Kelley Branch: Sure, so compass was actually developed as a partial three by two factorial. The arm that we're going to be talking about is the rivaroxaban arm. There was also another arm that tested the use of Proton pump inhibitors, and that actually was shown to not be as beneficial as we thought to decreased bleeding. But specifically for rivaroxaban, the baseline was aspirin, and this was on top of guideline based medical therapy. And then patients were randomized to either aspirin alone plus placebo or Rivaroxaban, five milligrams BAD, plus placebo. So, no aspirin at all or aspirin, a hundred milligrams daily, plus Rivaroxaban, 2.5 milligrams BAD. Those were really the three treatments. Patients were going to be followed for about three to four years. That's what we expected to get our 2200 events , an event-driven trial. But, because of the overwhelming benefits at 23 months median follow up, this trial was actually stopped early, so we only had a little over 1300 events at that time.
And with that we saw substantial reduction in major adverse cardiovascular events, about 24% mortality was reduced 18%, and there was a bleeding risk along with this, major bleeding, little different way of actually measuring major bleeding, but that was increased by about 70%, and that was the overall trial results. So, looking at the patients with heart failure, though, there was actually a relatively large proportion of patients, so 5,902 patients, about 22% of patients, actually had either baseline heart failure or had a history of heart failure coming in. Now, this was defined specifically by the PI's. These were not rigorously defined as compared to say commander, but these were patients where the PI said this patient has history or has chronic heart failure. So, with these 5,902 patients, we looked specifically at the outcomes of major adverse cardiovascular events similar to what we saw with compass and that is cardiovascular death, myocardial infarction, or any stroke, that combination. And then, looked at some others exploratory analysis like mortality.
And, what we found is that in patients with heart failure, the baseline rate was substantially higher for a mate's. Not too surprising because this tends to be a higher risk patient population. But, what we found is that the hazard ratio was about 0.68, so pretty similar to what we've seen the 24% relative risk. In this case, this was a 32% relative risk reduction in those patients with heart failure. Now, if we looked at a patients without heart failure, the hazard ratio is 0.79, so fairly similar and the [conference intervals 00:16:33] overlap. No statistical heterogeneity or no difference between those, but what we did see if we looked at the absolute risk reduction, was an absolute risk reduction in heart failure of 2.4% reduction. That means a number needed to treat of about 42. If you look at the absolute risk reduction for those patients without heart failure, that was 0.9 to 1.0 depending on what the rounding was. We took 1.0 so that means the number needed to treat of 103. So, these were slightly different relative risks, but overall, what we saw is that the hazard ratio is very consistent with the overall effect of compass in the same direction.
Interestingly, and actually I think even for me it was surprisingly, we actually looked at the hazard ratios for bleeding, and when we looked at the hazard ratios for bleeding, we fully expected that because it's the higher risk patient population, we actually expected that to go up. What we saw is that the bleeding actually was no difference at all, and if anything in the heart failure population was slightly lower. And, this was fairly surprising to us because we thought that the patients with heart failure, the bleeding would actually trend up because this was a higher risk patient population. So it looks like it's something can be used and really no substantial increase in bleeding.
Dr Greg Hundley: Very good. Well Carolyn, as someone that's managing patients with heart failure, what do you see are the clinical implications of this study?
Dr Carolyn Lam: That is a beautifully simple, direct question but is not as easy to answer as I may have thought. And, that's because the commander trial that Kelley did describe a bit earlier was neutral on its primary outcome. And, the commander trial is what we would traditionally think of as a heart failure trial. And why? Because those were patients that we rigorously define heart failure, including a naturally acid peptide inclusion criteria. And, because we really wanted these to be severe heart failure patients, we recruited them very close to their hospitalization or decompensation event. So, I just want to reiterate what Kelley has already so beautifully described that commander was neutral, whereas this heart failure subset of compass showed very impressive results that were consistent with the very impressive positive results of the overall compass trial.
So, how do we reconcile all of it? Well, first of all, I have to humbly remind myself that this heart failure subset of compass, the entire subset was actually bigger in numbers than the entire of the commander trials. So, this is not a small little subgroup analysis. This is a huge subgroup analysis. And that's why a paper like this, we're so proud to be publishing in circulation.
So, how do I apply it? Well, when I have a compass like patient, which means it's a stable coronary artery disease or peripheral artery disease patient who happens to have some mild heart failure. I think of this patient as a compass patient and I think that the combination of aspirin and low dose Rivaroxaban has been shown to be effective in these patients. So, in such a patient, I continue the aspirin rivaroxaban combination. However, if I have a new patient coming in with decompensated heart failure, a very low ejection fraction and has some coronary artery disease, by the way, I see that as a commander patient, and I just want to make sure that in such a patient I'm not trying to reduce their overall mortality by treating them with a combination of aspirin Rivaroxaban because commander has shown that I don't impact their overall survival with this combination, even though we may still have beneficial effects on their thromboembolic thrombotic events.
Kelley, would you agree?
Dr Kelley Branch: I would completely agree. That was actually born out very, very well by Barry Greenberg who had a really a wonderful sub analysis which he looked at the thrombotic events published in Jama cardiology and really showing that yes, you can affect the thrombotic events, but I mean really what it comes down to is we want to save lives. We want people to be better. There's just an overwhelming risk for these patients with heart failure that is really non thrombotic, primarily. And so, you're really not going to move the needle very much. You may prevent a stroke here, you may prevent some cardiovascular death from a thrombotic problem, but overwhelmingly pump failure, arrhythmia, et cetera. Those are really going to be the drivers for the commander like population.
Dr Carolyn Lam: But Kelley, this comes up a lot when we've chatted, but if you have a compass patient who has heart failure and then gets admitted with heart failure, what would you do then?
Dr Kelley Branch: That's a really interesting question, right? It depends on what the overall goal is. So, if the patient gets admitted for heart failure, now has it decreased ejection fraction sick. So has an MI, now decreased the ejection fraction. What's the end game? Right? Well you know, you may not be affecting mortality in this case because there's now competing events. However, if the goal was to decrease stroke, we've seen that. Still this goal is to decrease MI to some extent than we see that also. So, it would be reasonable to continue in order to prevent those events. But, just knowing full well that there's many other medications which actually do much better for the patients with decreased ejection fraction. And, those would probably be considered first line, but it's reasonable to continue. But, I would never start it.
Dr Carolyn Lam: Kelley, I couldn't agree more. And here I think the, your data showing that the bleeding risk is not significantly increased in this patient matters a lot. So, if I had a patient, a compass patient who was already on the combination and then gets admitted with heart failure, I too, if there's no additional bleeding risk, I would continue the combination as well.
Dr Kelley Branch: Couldn't agree more.
Dr Greg Hundley: Well listeners, this was a fantastic discussion, and we look forward to seeing you next week. Have a great week.
Dr Carolyn Lam: This program is copyright American Heart Association 2019.