May 3, 2021
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 and Duke National University of Singapore.
Dr. Greg Hundley:
And I'm Dr. Greg Hundley, associate editor, director of the Pauley Heart Center at VCU Health in Richmond, Virginia. Well Carolyn, it's another double feature Tuesday and today we get to discuss two articles. One, some insights from the CREDENCE trial. And second, another article about left atrial appendage closure devices, some results from the PINNACLE FLX trial. But before we get to those, how about we grab a cup of coffee and dive into some of the other really interesting articles in this issue? Would you like to go first?
Dr. Carolyn Lam:
I would, because this next paper, right up your alley and I'm sure you'll like it. But first, we talk about mitral valve prolapse. Now, we know that's a frequent disease that can be complicated by mitral regurgitation, heart failure, arterial embolism, rhythm disorders, and death. Left ventricular replacement myocardial fibrosis is a marker of maladaptive remodeling and has been described in patients with mitral valve prolapse. However, the implications of this finding remain scarcely explored. So these authors, led by Dr. [Le] Tourneau from Hôpital Laennec in France, aimed at assessing the prevalence, pathophysiological and prognostic significance of left ventricular replacement myocardial fibrosis through late gadolinium enhancement by cardiac magnetic resonance in 400 patients with mitral valve products. I bet you like that, right Greg?
Dr. Greg Hundley:
Oh my gosh Carolyn, not only a favorite topic of cardiovascular magnetic resonance, but this is a really large patient population with mitral valve prolapse that underwent CMR. So tell us, what did they find?
Dr. Carolyn Lam:
So replacement myocardial fibrosis was observed in 110 patients, so that's 28% of the patients. It was associated with mitral valve apparatus alterations, left ventricular remodeling, and ventricular arrhythmia. The ventricular arrhythmias were more frequent in patients with replacement fibrosis, but were not associated with the grade of mitral regurgitation. In patients with trace or mild mitral regurgitation, the presence of replacement myocardial fibrosis was nonetheless associated with specific mitral valve apparatus alteration at normal left ventricular dilatation, not explained by volume overload and ventricular arrhythmias, suggesting the presence of a mitral valve prolapse-associated cardiomyopathy.
Dr. Greg Hundley:
Wow Carolyn, really interesting. So the late gadolinium enhancement and the evidence therefore of replacement myocardial fibrosis that was identified by CMR, maybe this particular study is suggesting that we might want to integrate that into the clinical workup of patients with mitral valve prolapse. Very interesting work, and great job on that fantastic CMR presentation. I must say, got to recruit you into the club.
Dr. Greg Hundley:
Well, my next paper is another wonderful paper from the world of basic science and it comes from Dr. Douglas Lewandowski at the Ohio State University College of Medicine. So Carolyn, the failing heart is energy starved with impaired oxidation of long chain fatty acids at the level of reduced carnitine palmitoyltransferase-1, or CPT-1, activity at the outer mitochondrial membrane. Recent work shows that elevated ketone oxidation and failing hearts as an alternate carbon source for oxidative ATP generation. So Carolyn, these authors hypothesized that another short chain carbon source, short chain fatty acids that bypass CPT-1, could similarly support energy production in failing hearts.
Dr. Carolyn Lam:
Wow. Okay, so what did they find?
Dr. Greg Hundley:
So Carolyn, the failing heart oxidizes short-chain fatty acids more readily than ketones, with short-chain fatty acids also displacing long-chain fatty acid oxidation to somewhat of a greater extent. So in particular, the short-chain fatty acid butyrate has a higher affinity for entry into mitochondrial oxidation at the enzyme, short-chain Acyl-CoA dehydrogenase than does the ketone 3-hydroxybutyrate at the hydroxy butyrate dehydrogenase and then also through the respective downstream metabolic pathways for each substrate. So Carolyn, failing hearts of rats and humans have increased levels of Acyl coenzyme A synthetase medium chain three enzyme, which can also oxidize short-chain fatty acids to enhance butyrate oxidation.
Dr. Carolyn Lam:
Wow, that really is interesting. I can't say that I would have predicted that result. So could you give us a clinical implication?
Dr. Greg Hundley:
You bet, Carolyn. A lot of basic science here. So here's I think what we can take home, and what we learned. So while ketones have been sought as a potential supplemental fuel to remedy the impaired oxidative metabolism of the failing heart, this study shows that failing hearts preferentially oxidize short-chain fatty acids over ketones and short-chain fatty acids may prove to be a more efficient energy source during pathological stress.
Dr. Greg Hundley:
Next, novel alterations in metabolic pathways, favoring short-chain fatty acid oxidation in the failing heart occur in patients with non-ischemic cardiomyopathy. Then finally, circulating ketones are not a unique, super fuel beyond the ability to bypass the inhibition of long-chain fatty oxidation in the failing heart, as do the short chain fatty acids.
Dr. Carolyn Lam:
Thanks, I like the way you broke down the clinical implications. Well, Greg, I've got a question for you. Have you ever thought that statins may do more than lower cholesterol, but depending on what you eat?
Dr. Greg Hundley:
Oh wow, Carolyn. We always hear about the pleiotropic effects of statins, but I never really thought that could depend on what you eat. Tell me, so what did these authors investigate?
Dr. Carolyn Lam:
Yeah, so this next paper is so interesting. It's from Dr. Hu from Huazhong University of Science and Technology in Wuhan, China and colleagues, who present a novel perspective on the story of the pleiotropic effects of statins, exactly like you said, Greg. They started with the premise that statins exert pleiotropic or cholesterol-independent effects by reducing geranylgeranyl pyrophosphate production. I'm not going to keep saying that, so geranylgeranyl pyrophosphate or GGPP, is how I'm going to refer to it.
Dr. Carolyn Lam:
So they developed a sensitive technique to quantify dietary GGPP, and conducted proteomics, RT-PCR screening, and western blot, to determine signaling cascades, gene expression, protein-protein interaction, and protein-membrane trafficking in wild-type and transgenic rats, focusing on models of pulmonary hypertension, given their interest in the potential therapeutic efficacy of statins in pulmonary arterial hypertension.
Dr. Greg Hundley:
Interesting, Carolyn. Really complex and sophisticated. So what did they find?
Dr. Carolyn Lam:
Okay, listen up. Red meat and soybean have a high content of GGPP and their ingestion increases GGPP plasma levels, but reduces the effects of statins in rat models of pulmonary hypertension. Ingestion of garlic extracts, rich in methyl-L-phenyl sulfonate, which is a natural inhibitor of GGPP production, decreases GGPP bioavailability, and rescues statin effects in pulmonary arterial hypertension models. So consequently, first of all, diet may influence the cholesterol-independent effects of statins and the data really raise a provocative question of whether populations in which the typical diet contains high amounts of soybeans of beef may benefit less from statins. All this is discussed in an elegant editorial by Dr. Thomas Eschenhagen from Germany, who really ends with saying the present study should be considered hypothesis-generating and stimulate retrospective analysis of clinical registries and existing large interventional trials to either validate or refute this hypothesis. Whatever the outcome, the study is a nice example of thorough scientific underpinning of the widely held maxim that we are what we eat.
Dr. Greg Hundley:
Oh, absolutely Carolyn. I think next time with my spaghetti, I'll have the-
Dr. Carolyn Lam:
Garlic.
Dr. Greg Hundley:
... sauce with the garlic, but I won't add the red meats. Especially if I'm taking a statin.
Dr. Carolyn Lam:
Oh, that's what I was afraid you might say. Oh well, let me tell you about other papers in this issue. There's an ECG challenge by Dr. Del-Carpio Munoz and entitled A Carousel ECG Confusion. There's an on my mind paper by Dr. Hammond, on the importance of shared decision making for return to play after COVID-19.
Dr. Greg Hundley:
Great, Carolyn. So, in the mailbag, there's a really nice research letter from Dr. Robert-Ebadi evaluating the impact of the age-adjusted D-dimer cutoff to exclude pulmonary embolism. It's from a multinational prospective real-life study or the RELAX-PE study. Well Carolyn, it's another double feature Tuesday. How about we get off to understand a little bit more about those insights from the CREDENCE trial, and then also left atrial appendage closure devices?
Dr. Carolyn Lam:
All right, come on with your garlic breath.
Dr. Greg Hundley:
Well listeners, we are onto our feature discussions and we are very fortunate, we're going to have two feature discussions. Our first feature really addresses high blood pressure. And we have with us today, Dr. Brendan Neuen from the George Institute of Global Health in Sydney, New South Wales, Australia. And our own associate editor, Dr. Wanpen Vongpatanasin from UT Southwestern in Dallas, Texas. Welcome to you both. Brendan, we're going to start with you. Could you describe the hypothesis that you wanted to test and what was your study population and your study design?
Dr. Brendan Neuen:
Well, thanks Greg. In this study, what we wanted to assess was the blood pressure lowering effects of the SGLT-2 inhibitor canagliflozin in people with type two diabetes and chronic kidney disease. The reason we thought that this is important is because what we know about the blood pressure lowering effects of these drugs is largely based on people with normal kidney function, with relatively less data in people with chronic kidney disease. So we aim to assess both the blood pressure lowering effects of SGLT-2 inhibition in chronic kidney disease, as well as treatment effects by baseline blood pressure and other blood pressure defined variables. This was conducted in the CREDENCE trial, which was a large primary renal outcome trial of the SGLT-2 inhibitor, canagliflozin, which enrolled about 4,400 people with type two diabetes and chronic kidney disease with a urine albumin to creatinine ratio greater than 300 milligrams per gram and a GFR greater than 30 at enrollment. This was a high risk hypertension population, about 30% of patients had apparent treatment resistant hypertension, about 60% of people had a GFR less than 60 and about 20% of people were on four or more blood pressure lowering agents. So really high burden of hypertension in the CREDENCE trial.
Dr. Greg Hundley:
Very good. Tell us a little bit about that design. So is this a randomized trial?
Dr. Brendan Neuen:
So CREDENCE was an event-driven randomized, double blind, placebo controlled, international trial. It was the first primary renal outcome trial of an SGLT-2 inhibitor, the primary results of which were reported in the New England journal in 2019. What this trial did, was it randomized participants, as I mentioned, with a GFR of greater than 30 and significant albuminuria and type two diabetes to either canagliflozin 100 milligrams or matching placebo in a one-to-one ratio with primary outcome overall of doubling of serum creatinine, kidney failure, cardiovascular or renal death. The trial was conducted in several, I think, 20 or 30 countries overall and enrolled at approximately 4,400 people, with participants followed for a median of about two and a half years.
Dr. Greg Hundley:
Excellent. So Brendan, tell us, what did you find?
Dr. Brendan Neuen:
So we found a couple of important findings with regards to blood pressure. Firstly, what we found was that canagliflozin reduced systolic blood pressure by about three and a half millimeters of mercury in the overall trial population. But most importantly, this blood pressure lowering effect was consistent across the number of blood pressure defined subgroups, including in people on multiple numbers of blood pressure lowering agents. So irrespective of the number of blood pressure lowering agents at baseline, and also irrespective of a history of apparent treatment-resistant hypertension at baseline, that was important. We also, secondly, found that the blood pressure lowering effective SGLT-2 inhibition was present very early at the first trial visit at three weeks. This effect was sustained over the duration of the trial.
Dr. Brendan Neuen:
Thirdly, we also found that canagliflozin reduced the risk of kidney failure and cardiovascular events, regardless of the number of blood pressure lowering agents at baseline and regardless of blood pressure, history of resistant hypertension. Finally, there is this often important question of how do these drugs reduce the risk of kidney failure and heart failure. So we did a mediation analysis, looking at to what extent the blood pressure lowering effect of this drug explains the treatment effect on these important outcomes. We found that only about less than 10% of the treatment effect on kidney failure and cardiovascular events was explained by blood pressure lowering.
Dr. Greg Hundley:
Very interesting and strong, powerful results. Well, now we're going to turn listeners to our associate editor, Dr. Wanpen Vongpatanasin. Wanpen, I know you see a lot of papers come across your desk at circulation, really focused on blood pressure and its lowering. What struck you about this paper, and then how do you put into context the results that Brendan just describe for us with all the other results that you see in new blood pressure lowering strategies?
Dr. Wanpen Vongpatanasin:
Yes, so I think this is very important study and add to a body of literature showing that the canagliflozin, like many SGLT-2 inhibitors, inducing significant lowering of blood pressure. If anything, because CREDENCE is not designed to be hypertension study the effects of blood pressure lowering my even be underestimated because the backup ground therapy allowed to be changed throughout the trial, depending on physician judgment. Also, I think the effects of many studies start to look at effects of SGLT-2 inhibitor on out of office blood pressure, like home blood pressure, or 24 blood pressure. Some even that we have published over the years, show more pronounced blood pressure lowering effects when measure outside the office. So I think that it is very interesting study but it could be not just only the drug that we use cardiovascular and renal outcome, but maybe a new class of antihypertensive medication that we could use for that purpose, although it has to be tested.
Dr. Greg Hundley:
Very nice. Well, Brendan, I want to turn back to you and then we'll come to Wanpen. Brendan, what do you think as a followup study to yours, what do you think is the next study that needs to be performed in this space?
Dr. Brendan Neuen:
Thanks, Greg. I think there's so much we still need to know about the blood pressure lowering effects of these drugs in people with advanced CKD. It would be very interesting to look at the DAPA-CKD trial, to look at the blood pressure lowering effects in people with advanced CKD not due to diabetes, so nondiabetic kidney disease. These patients also have a high burden of hypertension and whether or not these effects are also present in this population would also be important to know, and study patients with even more advanced kidney disease. That is being done in the EMPA-KIDNEY study with empagliflozin. Those results should be known in the next 12 to 24 months.
Dr. Brendan Neuen:
So, I'm studying this further in people with kidney disease. And also as Wanpen mentioned, looking at effects on blood pressure phenotype, you know, 24 hour blood pressure dipping status would also be important though, blood pressure variability, all those things can add to our understanding of the effect of these agents on blood pressure.
Dr. Greg Hundley:
Excellent. And Wanpen, do you have anything to add?
Dr. Wanpen Vongpatanasin:
Yes. I think one also very important study that helps someone with carrying in the future is in the CREDENCE, the people who are already treated with a mineralocorticoid receptor antagonist were excluded. So whether among resistant hypertension group, adding canagliflozin will be beneficial in those groups already treated MRA and lower cardiovascular outcome in already treated with MRA will be very interesting to see.
Dr. Brendan Neuen:
Yeah, I think that's a really important point to point out about the design of the CREDENCE trial, that patients who were on MRAs were excluded from the trial initially. This was due to early concerns that canagliflozin might increase the risk of hyperkalemia. I think that risk has now been put to bed in the other SGLT-2 inhibitor trials. We've got more data looking at the effects on serine potassium coming out soon, hopefully, but the other trials in which enroll more patients on MRAs, it will be very important to look at the blood pressure lowering effects in these populations.
Dr. Greg Hundley:
Excellent. Well, listeners, we've heard a great discussion today and we want to thank Brendan Neuen for bringing this wonderful science to us through circulation at the American Heart Association. We also want to thank our associate editor, Wanpen Vongpatanasin for being present today and helping us discuss how, in patients with type two diabetes and chronic kidney disease, describing that the blood pressure lowering effect of canagliflozin occurs early and appears sustained over the long term and therefore perhaps canagliflozin and can be used or considered as an adjunct blood pressure lowering medicine in addition to perhaps its protective effects on the kidney and other cardiovascular-related issues. Well now listeners, we've got another feature to get onto. So we're going to get to that second feature discussion right now.
Dr. Greg Hundley:
Well listeners, we are now turning to our second feature discussion and we're so fortunate today to have with us Dr. Saibal Kar from the Los Robles Regional Medical Center in Los Angeles, California, and our own associate editor, Dr. Mark Link from UT Southwestern in Dallas, Texas. Welcome gentlemen. Saibal, let's start with you. Could you describe for us the hypothesis that you wanted to test and what was your study population and your study design?
Dr. Saibal Kar:
Dr. Hundley, or if I could allow to call you Greg, thank you very much for asking me this question. The hypothesis was that we do know that the WATCHMAN device does prevent ischemic strokes. We do know that the first generation device has a few limitations. So there were some modifications made to the new WATCHMAN device, which is now called the WATCHMAN FLX. We thought that these changes should translate into better safety and better efficacy. So, that was the hypothesis of the study. The study population was patients with nonvalvular atrial fibrillation with a CHADS-VASc score of three or more, who had high risk of bleeding or patients who cannot take long-term anticoagulants. The study design was a single arm, prospective multicenter study with endpoints, which were based on performance goals from previous clinical trials.
Dr. Greg Hundley:
Excellent. Before we get to your results, Saibal how many patients and how many centers participated in your trial?
Dr. Saibal Kar:
So as the national principal investigator, I've never seen a study which was enrolled so fast. So the intended population was 400 patients in 29 centers and before half those centers could be activated, the study was over in four months.
Dr. Greg Hundley:
Congratulations. I think all of us that have ... especially in this pandemic era for recruiting so well, and tell us, what did you find?
Dr. Saibal Kar:
So what we found is that there were two endpoints, a safety endpoint and the efficacy endpoint. So the first thing that we found is that of the 400 patients, we could actually implant in 395 patients, device actually, which made the primary success rate over 98%. regarding the safety endpoint, we had a safety margin around 4% based on a performance score and set about 2.5, but the actual safety event rate was 0.5%, which was only two minor ischemic events, peri-procedural. There were no pericardial effusions in the first seven days, and there was no device embolizations at any time period, so that was the primary safety endpoint. So we were actually clearly safer than the first-generation device.
Dr. Saibal Kar:
When it comes to efficacy, it was an anatomical efficacy and we set the primary goal for the previous generation to be 99%. We've made a delta to make it about 97% effective, but we actually achieved an effective closure in 100% of patients. When I say effective closure, I mean that anyone with a peri device leak of less than five millimeters. Going into a little bit of granular detail, we actually found out that 90% of the patients actually had no leak at all. So we did at least achieve both the anatomical as well as the safety endpoints.
Dr. Greg Hundley:
Excellent. Well, listeners, we're now going to turn to our associate editor, Dr. Mark Link and Mark, I know you have many papers that pass through your hands. What attracted you to this paper. Then, these results really sound significant. Can you describe what impressed you also with the results of this study and how do they relate to other studies pertinent to implantation of devices in patients with atrial fibrillation?
Dr. Mark Link:
Yeah, we were interested in this paper at CERT because it's the next generation of the WATCHMAN. The numbers of patients that are being implanted with this device to prevent strokes is dramatically going up, but it's not a perfect device. So we were, as the EP community, very interested in the next generation device. We're obviously also interested in other competitors' device, but it's clear that the WATCHMAN is probably the world's leader in this time. So we knew that many of our people reading this magazine, reading the circulation, would want to see how the next generation turned out, was it really safer. That was really the primary goal of this study, it's really a safety study more than an efficacy study because the efficacy was defined by echo criteria, not by clinical criteria of stroke, which is the ultimate criteria. It was a well done study and the results came out more positive than I think even the investigators thought it was going to come out. So we liked it and that's why we did our best to get it published in circulation.
Dr. Greg Hundley:
Very good. So it sounds like great new innovation and very, very safe, especially relative perhaps to the first-generation device. So Saibal, can you tell us in just a few words, what do you think is the next study to be performed in this space? After you answer, Mark, we'll turn to you and basically ask the same question.
Dr. Saibal Kar:
Thank you very much, Greg. Transcatheter left atrial appendage closure has been approved by the FDA, specifically the WATCHMAN device, for patients who are candidates for long anticoagulation, but have limitations to long-term anticoagulation and therefore not for all-comers and there's a reason for that. The time has now come to actually evaluate this device for all-comers. That means all patients with nonvalvular atrial fibrillations who are suitable for anticoagulants. Therefore, the next best study is the CHAMPION trial. This study is going to be a randomized trial of the WATCHMAN FLX versus NOACs, or more correctly DOACs, in all-comers, patients with nonvalvular atrial fibrillation who require long-term anticoagulants. It's a 3,000 patients clinical trial with a one-to-one randomization to WATCHMAN FLX or the continuation of DOACs and the primary endpoints will be estimated at three years with a follow-up up to five years. Our goal is to show that we are non-inferior in comparison to stroke and death, and superior respect to long-term bleeding.
Dr. Greg Hundley:
Very good, and Mark?
Dr. Mark Link:
Yeah, I agree. The CHAMPION trial is the obvious next trial that everyone wants to see the results of, comparing this device to DOACs. Another trial or data I'd like to see is the immediate post-procedural anticoagulation. It's still an area that we don't have enough data to know how to treat these patients. Traditionally, they've been treated with warfarin and anti-platelet agents, but many of the patients getting this WATCHMAN have a relative contraindication to anticoagulation. So I'd like to see some data on shorter term duration of anticoagulation post-implant.
Dr. Greg Hundley:
Very good. Well listeners, we've had a wonderful discussion here and we want to thank the lead author, Dr. Saibal Kar and also our own associate editor, Dr. Mark Link, for really providing us with new information that this left atrial appendage closure device met the primary safety outcome in 99.5% of all of those implanted within seven days, what a remarkable finding. So, on behalf of Carolyn and myself, we want to wish you a great week and we will catch you next week on the Run. This program is copyright of the American Heart Association, 2021.