Mar 2, 2020
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, director of the Pauley Heart Center at VCU Health in Richmond, Virginia. You know that problem we have with the development of calcification of the aortic valve, the aorta, etcetera with hemodialysis? Well, our feature is going to talk about the results of a randomized phase 2B study to address this. But first, how about if you get us started with a couple of your papers?
Dr Carolyn Lam: In fact, it is a couple of papers and they're both related to hypertension. So in the first one, we know that exercise is associated with a lower incidence of hypertension, but what's the association of excessive levels of exercise in the incidence of hypertension? This question was examined by Dr Andersen from Uppsala University Hospital and colleagues, who compared the incidence of hypertension among almost 207,000 participants in a long-distance cross-country skiing event and more than 505,500 persons randomly sampled from the general population who are matched to the skiers on age, sex, and place of residence.
Dr Greg Hundley: I love skiing! I want to be in the match group. Tell me, now, how long was this distance that they had to cover?
Dr Carolyn Lam: Ah ha. Now the long distance event was really long. It was the Vasaloppet. I hope I pronounced that right, but it's a 45 to 90 kilometer skiing race. So participation, I'm sure you want to hear this, participation was associated with a 41% lower incidence of hypertension over the next eight years, compared to non-participation. And the better the performance in terms of percent of winning time, the lower the incidence of hypertension. If the observed associations are causal, it really adds to the list of beneficial effects of high, or even very high physical fitness. I can see you smiling, Greg.
Dr Greg Hundley: This is your confirmation that the AHA wants to send us to Norway to do one of these recordings.
Dr Carolyn Lam: Well, this next paper asked the question, what is the association of cumulated blood pressure exposure from young adulthood to midlife with gait and cognitive function in midlife. This is from Dr Mahinrad from Northwestern University Feinberg School of Medicine and colleagues who included 191 participants from the coronary artery risk development in young adults’ study, which is a community-based cohort of young individuals followed over 30 years. Cumulated blood pressure was calculated as the area under the curve for baseline up to year 30 exam and gait and cognition were assessed at the year 30 exam. Cerebral white matter hyperintensity was available at year 30 in a subset of participants who underwent MRI.
Dr Greg Hundley: I heard that MRI word. So what did they find Carolyn?
Dr Carolyn Lam: They found cumulative exposure to higher blood pressures from young adulthood to midlife, even at levels below the clinical definition of hypertension, was associated with worse gait and worse cognitive function in midlife. The impact of cumulative levels of blood pressure exposure was independent of other vascular risk factors during a follow-up period of over 30 years, and the higher burden of midlife cerebral white matter hyperintensity on MRI, Greg, moderated the association of cumulated blood pressure exposure with gait but not with cognitive function.
Dr Greg Hundley: You've got me convinced we now have to go to Norway. But what did the authors think were the clinical implications of their study?
Dr Carolyn Lam: Well, here it is. The deleterious effect of elevated blood pressure on brain structure and function may begin during early adulthood and this really emphasizes the need for all primordial, if you may, prevention of high blood pressure. But also reconsidering individual levels of blood pressure for the diagnosis of hypertension. Furthermore, gait may be an earlier measure of hypertensive brain injury than cognition. Now these issues are discussed an editorial by Angela Jefferson from Vanderbilt University Medical Center.
Dr Greg Hundley: Very nice, Carolyn. Well, I'm going to take another sort of twist on hypertension. My paper is from Dr Thomas Thum from the Hanover Medical School and is really looking at the relationship between cardiac fibrosis and diastolic dysfunction. So the study sought to identify anti-fibrotic drug candidates by functional screening of 480 chemically diverse natural compounds found in human cardiac fibroblasts.
Dr Carolyn Lam: Ooh, interesting. And what did they find?
Dr Greg Hundley: What they found is using multiple in vitro fibrosis assays and stringent selection algorithms, the authors identified the steroid bufalin, also seen in Chinese toad venom, and the alkaloid lycorine, from the Amaryllidaceae species, to be effective anti-fibrotic molecules, both in vitro and in vivo, leading to improvement in diastolic function in two hypertension dependent rodent models of cardiac fibrosis. In addition, administration of these agents at effective doses did not change plasma damage markers, nor the morphology of the kidney and liver. And therefore, it's kind of an early first toxicological safety study.
Dr Carolyn Lam: Fascinating. Not just in the findings and the methods, and who knew we'd be talking about Chinese toad venom on this podcast, Greg? Okay. But let me tell you about what's more in this issue. So, there is a research letter by Dr Djoussé, and it is entitled Supplementation with Vitamin D and/or Omega-3 Fatty Acids and the Incidence of Heart Failure Hospitalization. And this one is a letter from the VITAL-Heart Failure ancillary study of the parent VITAL trial. I'm sure I've got everyone's attention. (You) Got to read that letter.
The next is an On My Mind, by Dr Joe Hill, and is entitled, very intriguingly, Can HFpEF and HFrEF Co-exist? Basically accumulating evidence has revealed that the pathophysiologic mechanisms driving HFrEF and HFpEF are distinct, but this On My Mind paper asks can they coexist? Is it possible to identify subjects who harbor pathophysiological elements of both syndromes simultaneously, and if so, we may find that targeting specific pathways is beneficial and in depth characterization of specific subsets of patients might help overcome the limitations of an ejection fraction driven approach.
Dr Greg Hundley: Very interesting, Carolyn. I've got some letters from the mailbox, and the first letter is regarding SGLT2 inhibitors in cardiac hypertrophy and the corresponding author is Professor Kazushi Tsuda from Kansai University of Health Sciences. Another letter, from the corresponding author Dr Renato Lopes from Duke University Medical Center in Durham, evaluates stent thrombosis in patients with atrial fibrillation undergoing coronary stenting from the AUGUSTUS trial. And our own Tracy Hampton provides an update on cardiology news features. And John Warner, from UT Southwestern, the prior American Heart Association president, discusses his journey through healthcare reform. And then finally, our own Sarah O'Brian provides highlights from other journals in the Circulation family related to high points in cardiovascular disease. Well, Carolyn, how about on to dialysis and calcification?
Dr Carolyn Lam: Can't wait. Let's go.
Our feature discussion today, we will be focusing on patients with end-stage kidney disease. And we know that in these patients, the high cardiovascular morbidity and mortality could partially be due to extensive cardiovascular calcification. Well, our feature paper today is the first double blind placebo-controlled phase 2B trial that tests intravenous myo-inositol hexaphosphate, a novel strategy to inhibit the formation and growth of hydroxyapatite and therefore reduce calcification in these patients. I won't tell you more. I'll leave that to the corresponding author, Professor Paolo Raggi, from University of Alberta, and I'm also so pleased to have with us our editor for digital strategies and associate editor Dr Amit Khera from UT Southwestern. So Paolo, please tell us about SNF472 and your very novel trial.
Prof Paolo Raggi: As you correctly stated, patients with end stage renal disease have phenomenally high morbidity and mortality, particularly cardiovascular, and they also manifest extreme calcification on the cardiovascular system. Both the valves and the vessels are very heavily calcified. There's a very clear impression throughout the literature that calcification contributes, no doubt, to the high morbidity mortality with these patients. SNF472 is a derivative of a natural product that is only present in nature in sub molecular quantities and essentially is administered intravenously and the mechanism of action is quite simple. It keeps calcium and phosphorous molecules separate. In other words, it doesn't allow crystallization of calcium and phosphate into what we call hydroxyapatite, or amorphous calcium crystals. This, hopefully, was developed, this product was developed, to inhibit the final step of calcification. Everything comes down, no matter what the promoting event is, to crystallization of calcium and phosphorus. Therefore, if we were able to stop the final event, hopefully you will be able to inhibit further calcification, and that's what we tested in this particular article, in this particular study.
Dr Carolyn Lam: Oh Paolo, I just love the way you described that. Very, very crystal clear, if you don't mind the pun. But could you please let us know, so a phase 2B trial, does that mean a surrogate outcome, duration of treatment, number of patients? How about telling us a little bit about the trial?
Prof Paolo Raggi: So, the trial involved recruiting three different groups of patients. One would be treated with placebo and two other cohorts would be treated with either 300 milligrams of SNF472 three times a week or 600 milligrams of SNF472 three times a week. The product is injected intravenously into the dialysis line. Therefore, the patients do not have to remember to take a pill or inject themselves. Actually, it's perfect, if you will, compliance because all they have to do is come to their dialysis session and they receive it during dialysis.
The study therefore, it was a relatively small study, but enough to prove our point. Three groups were recruited, about 90 patients each, and the two treatment arms at 300 milligrams and the 600 milligrams, were combined as a single group for the purpose of reporting the primary results. The follow up was at one year, so these patients were submitted to CT scanning of the chest without contrast for measurement of calcification only at baseline and then again at 52 weeks. In the intention to treat group, patients were included if they had a baseline scan and at least one follow-up scan at some point during the study. These are very sick patients and sometimes are referred for transplant. Sometimes they withdraw from studies. So, we asked everybody to have a second scan if they needed or wanted to withdraw before the 12 month mark was reached. That's for the intention to treat analysis. And then we need some confirmatory analysis on patients who actually did have the baseline in an actual 12 months scan and received the entire year treatment with these two drugs, with a drug or placebo.
Dr Carolyn Lam: That's great and please tell us the results.
Prof Paolo Raggi: The results were, in our minds, very exciting. And let me first say, that in all the literature that looked at what is the average progression of calcification in the general population, it's anywhere between 10 to 15% per year. For the person with calcium in the coronary arteries, there's an expected progression about 10 to 15%. All the publications in patients with renal failure and undergoing dialysis, show the progression of anywhere between 25 and 35%, so these people are not only more calcified, these patients also progressing very fast. In the particular trial that we reported in Circulation, we demonstrated on average, a progression of 20% in the group receiving placebo and about 11% in the group receiving SNF472. So, there was about a 45% slowing of progression in the treated group compared to the placebo group.
Interestingly enough, we saw a slower progression unusual in the placebo group. As of today, many more treatments are available to patients with end stage renal disease that were not available when the original studies that I mentioned earlier were conducted. So, the 25 to 35% progression that we saw 15 years ago, it's now slowed, you notice, to a 20% progression in these patients, but SNF472 was even more effective at further slowing that progression.
Dr Carolyn Lam: Well, congratulations first and foremost on a very successful and really striking and novel results. Well, Amit there's so much to discuss I don't even know where to start. But first, maybe can I bring you in by saying, so what, is Circulation now publishing renal papers?
Dr Amit Khera: The answer is absolutely yes. So first I want to congratulate Dr Raggi on a fantastic paper. This was a concomitant late breaking science at the American Heart Association Sessions; so, we always try to think of timely and exciting topics and appreciate working so closely with this group to bring this across the finish line. At Circulation, one thing we've been working on is something called Bridging Disciplines, where purposefully we appreciate the heart is not in isolation and not in a box by itself, but within a larger system, a body system. So, we really enjoy these types of papers that cross disciplines and there's an outstanding editorial by Susan Hedayati, from UT Southwestern who's a nephrologist, who weighed in here as well. So we certainly really value these types of papers in Circulation.
Prof Paolo Raggi: I have to say, working with Circulation was amazing. You know, you get a great job and so fast. It was an incredible, actually.
Dr Amit Khera: Obviously, the results speak for themselves that the study was positive, and we certainly see this diminishing the vascular classification and certainly you've been, for decades now, an expert in vascular calcification and coronary imaging. And you know, the question that always comes up is, what are the implications here? Now, on one side, especially with the coronaries, you think this would be favorable, you get less obstructive disease, perhaps less ischemic heart disease. But there's always been this debate if calcium's a good or bad thing in terms of plaque stabilization, so what are your thoughts on what ends up being the clinical ramifications of this down the road?
Prof Paolo Raggi: Well of course, as we clearly stated in the paper, this has to be followed by some sort of clinical outcome study. So, it is only speculating at this point as to what the benefit might be. But more specifically about your question, I think that there is a misinterpretation of what calcification means in general. And honestly, I would prefer not to have calcification in my cardiovascular system if I had the choice. Many believe, and it's possibly true to a degree, that calcification comes in to repair the plaque and there's some sort of repair mechanism, but we have shown very clearly that the greater the calcification burden, the higher the probability of cardiovascular morbidity mortality. And therefore, it is not benign to have cardiovascular calcification in general.
In the case of the patients with end stage renal disease, calcification is not limited to the atherosclerotic plaque. It extends to the thickness of the entire vessel wall and it's well known that patients with end stage renal disease have severe calcification of the media as well as the intima. This obviously causes a series of other problems, such as stiffening of the vessels and therefore reduce compliance and in the long run, many profusion issues to multiple organs, even in the absence of luminal stenosis. A stiff vessel does not comply with what it's supposed to be doing. It is not allowing proper profusion of an end organ and many have demonstrated that also increases the work of the heart, pumping against very rigid plumbing, if you want to put it that way and simply, and therefore may induce left ventricular dysfunction in the long run, arrhythmias if a patient develops left ventricular hypertrophy and fibrosis. So, I think that there's a cascade of events that goes beyond and above just the single plaque, atherosclerosis, calcification. I think that calcification in general, and especially in patients with end stage renal disease, is a whole marker, very high risk of complications.
Dr Amit Khera: Thanks for that clarification. I think first and foremost, it's so helpful to think beyond just isolated luminal stenosis and sort of all the maladaptive aspects of vascular calcification in patients with end stage renal disease. And that leads to the next thing in your paper, which I thought was also really interesting, which was the aortic valve calcification. We certainly appreciate that focus on aortic stenosis as of late with the new therapies, but you know particularly in patients with end stage renal disease, it becomes a very complex issue. And you saw some abating of this vascular calcification in the aorta as well. Tell us a little bit about what you think the implications of that would be.
Prof Paolo Raggi: So first, a word of caution that the trial was not powered to demonstrate specifically an effect on aortic valve. However, we did demonstrate a beautiful effect on the slowing of the aortic valve calcification as well. It's exciting! I think that it's something that needs to be pursued further and I hope future studies, and definitely is the first time that anything has demonstrated an effect on aortic valve calcification. I'm very well aware of other studies that have attempted, for example, use of statins to slow the progression of valvular calcification and in essence, were completely negative. Patients with end stage renal disease, very severe valvular abnormalities, very, very severe, very important valvular dysfunction as a consequence of massive calcification on the annulus and the leaflets more so of the aortic valve, but also the mitral valve. So this could definitely be a signal for an excellent potential and unexpected if you will, a secondary outcome of this treatment. I believe that in affecting valvular calcification in patients with end stage renal disease would be, could have potentially a massive effect from the point of view of lowering the cardiovascular event rate.
Dr Carolyn Lam: May I chime in with a quick question? What were adverse effects like?
Prof Paolo Raggi: This particular drug actually was associated with the same exact rate of adverse effect as placebo. In other words, we didn't see anything at all that was alarming. There was one patient that had been reported by the investigator as potential side effect of the drug. They reported something, I think it was like acute hepatic failure, but when the case was clearly analyzed by the DMV, we actually assessed dictation as being a case of cholecystitis had been incorrectly labeled, we believe. And except for that one case, there essentially were no side effects, no adverse effects from treatment. In fact, although it was not powered for those outcomes, there was a lower morbidity and mortality with the SNF472 and then with placebo.
Dr Carolyn Lam: I really like that and was really struck by your pointing out a little bit earlier, the ease of administration as part of hemodialysis. That was very nice. Amit, I'm going to give you the final words and questions if I may.
Dr Amit Khera: As expected, this has been an exciting podcast and as much as I've read this paper and looked at it in detail, I learned a lot more as I had anticipated. My question for you, Paolo, now, is what's the next step? This is a phase 2B study. What's the next step in the development or evaluation of this compound and where are you going with this?
Prof Paolo Raggi: There are a few sub analysis that we haven't yet looked at in this particular study that we just reported. One of the things that we are definitely interested in is to evaluate the effect on bone. As you can imagine, it is true that this particular drug has a wonderful effect on vascular calcification, but the next question is, did it do anything adverse to the bone? It's a logical question but I feel that most likely the answer is going to be a resounding no.
But, besides that, the further development of this drug is obvious in my mind. It will have to be addressed in a proper, randomized clinical trial to address some of the clinical questions that we all have. Is this reducing the cardiovascular events? Be it when we need, we will decide together what those cardiovascular events would look like. But obviously myocardial infarction, congestive heart failure, admission for unstable angina, cardiovascular deaths in general, those are going to be very important questions to be answered in a further step. Before we get there, there are a few other questions that we have for the drug itself from this particular 2B study that we can still look at.
Dr Amit Khera: Excellent. Looking forward to those subsequent analyses.
Dr Carolyn Lam: Thank you and we look forward to the next publication on Circulation.
Dr Amit Khera: Absolutely.
Dr Carolyn Lam: I'm sure the audience is actually looking forward to more such discussions as these. Remember, you've been listening to Circulation on the Run.
Dr Greg Hundley: This program is Copyright The American Heart Association 2020.