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Circulation on the Run


Nov 23, 2020

This week’s episode features author Emma Birks and Associate Editor Hesham Sadek as they discuss the article " Prospective Multicentre Study of Myocardial Recovery Using Left Ventricular Assist Devices (REmission from Stage D Heart Failure: RESTAGE-HF): Medium Term and Primary Endpoint Results."

TRANSCRIPT BELOW:

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 of VCU Health in Richmond, Virginia. Carolyn, our feature article this week, we're going to examine myocardial recovery using left ventricular assist devices, getting some early results from the RESTAGE-HF study. But before we jump to the feature discussion, how about we discuss some of the papers in the issue? Would you like to go first?

Dr. Carolyn Lam:

Yes I would. Have you thought about what's the benefit of emergent coronary angiography after resuscitation from out of hospital cardiac arrest for patients without ST elevation? It's an important question. Well, the portal study was reported by Dr. Kern from University of Arizona and colleagues, and this was designed to evaluate the efficacy and safety of early coronary angiography and to determine the prevalence of acute coronary occlusion in resuscitated out of hospital cardiac arrest in patients without ST elevation. So adult comatose survivors without ST elevation after resuscitation, were prospectively randomized to early coronary angiography versus no early coronary angiography, where early was defined as less than 120 minutes from arrival at the PCI capable facility. The primary endpoint was a composite of efficacy and safety measures, including efficacy parameters of survival to discharge favorable neurological status at discharge echo measures of left ventricular ejection fraction, more than 50% and a normal regional wall motion score within 24 hours of admission.

Dr. Greg Hundley:

So, lots of data here. What did they find?

Dr. Carolyn Lam:

So, unfortunately the study was prematurely terminated before enrolling the target numbers of patients. A total of 99 patients were enrolled from 2015 to 2018 and 49 were randomized to early coronary angiography. The primary endpoint of efficacy and safety was not different between the two groups. Early coronary angiography was not associated with any significant increase in survival or adverse events. And early coronary angiography revealed a culprit vessel in 47% with a total of 14% of patients undergoing early coronary angiography, having an acutely occluded culprit coronary artery. So while this was an underpowered study, when considered together with previous clinical trials, it does not support early coronary angiography, comatose survivors of cardiac arrest without ST elevation, whether early detection of occluded potential culprit arteries leads to interventions that improve outcomes does require additional study. And this is discussed in an editorial by Dr. Lemkes from Amsterdam university medical center.

Dr. Greg Hundley:

Very nice Carolyn. So at least the study that points us toward the next study that has to be performed and also does with other studies provide a little more clarity. Well, my next paper is from Professor Sanjiv Shah and--oh, wait a minute! And also from you as a co-author. Well, Carolyn, how about we have a little mini feature discussion where I can ask you some questions and then you can tell us all about your paper.

Dr. Carolyn Lam:

Happy to.

Dr. Greg Hundley:

Great. So Carolyn, what hypotheses were you testing and what was your study design and who was included in your study population?

Dr. Carolyn Lam:

Okay. So the question was we wanted to answer was thus a systemic pro-inflammatory state as indicated by proteomic profiling. Does that mediate the association between comorbidities and normal cardiac structure and function in HFpEF. To answer that we studied 228 patients with HFpEF from our multicenter promis HFpEF study. And these patients had 248 unique circulating proteins quantified using the old link multiplex immunoassay. Now I'm going to describe a complex analysis, but we basically had to first perform principal component analysis. And we did this to summarize 47 proteins known a priori to be involved in inflammation, and then used unbiased network analysis of all the 248 proteins to identify clusters of proteins that over-represented inflammatory pathways. We then used a mediation analysis to determine whether and to what extent inflammation mediates the association of comorbidity burdens with abnormal cardiac structure and function. And finally, we externally validated our findings in an independent cohort of 117 HFpEF cases and 30 comorbidity controls without HFpEF.

Dr. Greg Hundley:

Wow Carolyn, such a great design and an app machine learning mediation analyses, and then validation in an independent cohort. So tell us, what did you find?

Dr. Carolyn Lam:

So first, comorbidity burden was associated with abnormal cardiac function and structure and with these principle components of clusters of inflammation proteins. Second, systemic inflammation was associated with echo indicators of worse hemodynamics, like higher EDE' ratio and worse, right ventricular function. And third, inflammation indeed mediated the association between comorbidity burden and many of these echo parameters with, and I'm going to name a couple of routines. So TNF-R1, uPAR, IGFBP-7 and GDF-15 being the top individual mediating proteins. In the validation cohort inflammation was up-regulated in HFpEF compared to controls and the most prominent inflammation protein cluster identified was also the same one as in PROMIS-HFpEF.

Dr. Greg Hundley:

Beautiful Carolyn. So with these new proteins identified, what's the take home message here?

Dr. Carolyn Lam:

Here it is. Proteins involved in inflammation form a conserved network in HFpEF. And this was found across two independent cohorts. This may mediate the association between comorbidity burden and echo indicators of worst hemodynamics and right ventricular dysfunction. In totality, these findings support the comorbidity inflammation paradigm in HFpEF.

Dr. Greg Hundley:

Great job Carolyn, I liked the mini feature. That was so nice having one of the authors of the study here to explain kind of a two for one here, because we're going to get a feature and a mini feature. Have you got another paper you want to tell us about?

Dr. Carolyn Lam:

Thanks Greg and that works both ways. This next paper provides insights into the identity origin and function of many cells that make up late stage atherosclerotic lesions. It also identifies the mechanisms by which these control plucks stability. So corresponding author, Dr. Owens from Virginia School of Medicine and colleagues conducted a comprehensive single cell RNA sequencing of advanced human carotid endarterectomy samples, and compared these with murine micro dissected advanced atherosclerotic lesions with smooth muscle cell and endothelial lineage tracing to survey all plaque cell types and to rigorously determine their origins.

Dr. Greg Hundley:

Carolyn you know, this is another great study where we have both human subjects research and small animals. What were their results?

Dr. Carolyn Lam:

They provided evidence that smooth muscle cell specific knockout of transcription factors, KLF4 versus Oct-4 showed virtually opposite genomic signatures and their putative target genes played an important role, regulating smooth muscle cells phenotypic changes. They also provided evidence that smooth muscle cell derived cells within advanced mouse and human atherosclerotic lesions exhibited far greater phenotypic plasticity than generally believed, with KLF4 regulating the transition to multiple phenotypes, including LGALS 3 plus osteogenic cells likely to be detrimental for late stage atherosclerosis plaque pathogenesis. So in summary, smooth cell phenotypic switching produces cells that can be beneficial or detrimental to lesion stability and may be an important mechanism controlling the risk of unstable atherosclerotic plaque and myocardial infarction or stroke.

Dr. Greg Hundley:

Oh, great job, Carolyn. Well, the next paper I have is from Professor Muredach Reilly from Columbia University. And Carolyn smooth muscle cells play significant roles in atherosclerosis via phenotypic switching, a pathological process and with smooth muscle cell D differentiation, migration and trans differentiation into other cell types yet how smooth muscle cells contribute completely to the pathophysiology of atherosclerosis remain somewhat illicit. So the authors sought to reveal the trajectories of smooth muscle cell trans differentiation during atherosclerosis, and to identify molecular targets for disease therapy by combining smooth muscle cell fate mapping and single cell RNA sequencing of both mouse and human atherosclerotic plaques.

Dr. Carolyn Lam:

Echoing what you said earlier, Greg, both animal and human data. Terrific. So what were the results?

Dr. Greg Hundley:

The authors found that smooth muscle cells transitioned to an intermediate cell state during atherosclerosis, which was also found in human atherosclerotic plaques of carotid and coronary arteries. Smooth muscle cell derived intermediate cells termed stem cells were multiphoton and could differentiate into macrophage like and fibro chondrocyte like cells as well as returned towards the smooth muscle cell phenotype. Retinoic acid signaling was identified as a regulator of the transition of smooth muscle cells to stem cells and RA signaling was dysregulated in symptomatic human atherosclerosis. Finally Carolyn, human genomics revealed enrichment of genome-wide association study signals for coronary artery disease in RA signaling target gene low PSI and correlated between coronary artery disease risk levels and repressed expression of these genes. Now, activation of RA signaling by all trans retinoic acid and the anticancer drug for acute promyelocytic leukemia blocked the smooth muscle cell transition to stem cells, and that also reduced atherosclerotic burden and then promoted fibrous cap stability. So a lot of clarification of the role of smooth muscle cells, trans differentiation and the development of atherosclerotic disease

Dr. Carolyn Lam:

Indeed and translational implications. Interesting. Now let's review some of the other papers in this issue. Shall we? First as an, on my mind paper by Dr. Kullo on familial hypercholesterolemia, a reportable disorder. There's an exchange of letters between doctors Lazzerini and Li regarding the article autoantibody signature in cardiac arrest.

Dr. Greg Hundley:

Thanks Carolyn. Well, I've got a couple other papers to tell you about really a series of research letters from the mailbag. So first Daniel Modin has a Research Letter entitled “Acute COVID-19 and the Incidents of Ischemic Stroke and Acute Myocardial Infarction.” Dr. Christian Mueller has a Research Letter entitled “Effect of a Proposed Modification of the Type 1 and Type 2 Myocardial Infarction Definitions on Incidents and Prognosis.” And finally Carolyn a Research letter from Dr. Jizheng Wang involving an East Asian-specific common variant in TNNI3 that appears to predispose to hypertrophic cardiomyopathy. Well, Carolyn, what a great issue and thank you for that many feature, but how about we proceed on next to our feature discussion?

Dr. Carolyn Lam:

Let's go, Greg.

Today's feature paper is one of those that I think is going to change clinical practice. So please listen up. It's about the RESTAGE-HF study. So pleased to have with us the first and corresponding author, Dr. Emma Birks from University of Kentucky Gill Heart and Vascular Institute, as well as our associate editor, Dr. Hesham Sadek from UT Southwestern to discuss this very important paper. Emma, could you please describe the RESTAGE heart failure study?

Dr. Emma Birks:

Let's say prospective study of patients getting left ventricular assist devices. So patients with very advanced heart failure are receiving left ventricular assist devices as either a bridge to transplant or as destination therapy. And they're seeing them for chronic heart failure because really all other medical therapy has failed and we use the pump to try and recover their own heart. So when the pump's implanted, we optimize the LVAD unloading, the maximum loading, and we give them a very aggressive medical therapy regime, unless they may not have tolerated these medications before because of poor blood pressure and renal dysfunction, we find they do tolerate them. So we give them in very aggressive doses and then we monitor their underlying function at regular intervals and try and promote recovery. So with that, we had done this in England in the past, in a single center study, but it had not yet been reproduced, which was obviously essential to have a bigger impact.

Dr. Emma Birks:

So we did a prospective study of six big US centers. We found that we've created a primary endpoint that was statistically powered in advance. And the primary endpoint was the number of patients that recovered within an 18 month period, that were explanted and remained off the pump and alive without transplant over for one year. So overall we found that of the 40 patients we recruited in the centers with chronic heart failure, we were able to explore 19. Of those that satisfied the primary endpoint, that was actually 40% of patients, with 52.3% being explanted overall. And importantly, patients were explanted in all six centers, so we found that the protocol was reproducible under the how much higher rate of recovery that you would otherwise see. Normally there is a database in the US that tracks outcomes from bad patients. And generally only 1-2% seemed to recover enough to be explanted generally. So this was a much bigger percentage.

Dr. Carolyn Lam:

Emma, first of all, congratulations, what an important trial and what stunning results. More than half of patients receiving that protocol were explanted. That's just remarkable. Now, could I just ask, what is it that you did that was different? I noticed you spent a lot of time saying this was an aggressive pharmacological protocol that was along with the LVAD unloading. Could you maybe elaborate on that a little bit more?

Dr. Emma Birks:

Yeah, I think that was a very important part of it. So generally I think when the LVAD goes in most centers, the patients are very sick, so most of those patients wouldn't then try and recover them or look at underlying functions. I think that was the first thing that was different was to try very hard. And then we had centers, the experience, I had done this before, it was also very helpful, all agreeing to do the same thing. We use a very aggressive regime of ACE inhibitors, Beta blockers, auto serotonin antagonists and ARBs. And that was also an unusual thing. We use the fact that they're supported with the pump to use both an ACE and an ARB together, but the idea that they have better blood flow in the cranial is way more tolerant and we give very high doses. So we use Lisinopril with the target dose of 40 milligrams, Coreg with a target dose of 50 BID, Aldactone 25 milligrams daily.

Dr. Emma Birks:

And then we add in losartan if they tolerate it and actually aim for 150 milligrams daily, so those doses are very high. And I think not normally given to people on LVADs. So you must've had the LVAD that don't tolerate the medical therapy and stop it. They might just have blood pressure control, etc. There is now also another INTERMACS trial, a sort of big study that's come out that actually shows benefit of neurohormonal antagonists in general. So that goes together with our study to show that they should already be given and then the regular testing. So we had quite thorough testing. So first of all, we do echos on the pump and then we do echos with the LVAD turned down to a speed at which is not contributing. So we do that and we do an echo at five minutes with it down 15 minutes, and then we walk the patient, distress them. Once we show that the hearts come down in size and improved function, then we do an exercise test, right heart cath on an off pump to look at the hemodynamics.

Dr. Carolyn Lam:

Wow. So tremendous effort and really the protocol is unique in and of itself, not just the pharmacological therapy, also the way this is monitored and decisions are made really, really amazing. Just one last question for me, because it's a humbling reminder of the importance of neurohormonal blockade in these patients. Do you continue that after they're explanted?

Dr. Emma Birks:

Yes, we do. And we continue aggressively and that's slightly different as well in that normally you wouldn't give a patient a nascent an up of course, but given that they've already tolerated it on the pump in that same patient. So we restart the same drug regime afterwards, and we actually like to get them to quite along that dosage before we discharge them from the XPLAN, we don't want to do that slowly. We get them back on it quite quickly. And then we follow them very carefully because we don't really know the long-term durability.

Dr. Carolyn Lam:

Wow, thank you. Hesham. I would love your thoughts on this paper. I mean, it really, really is remarkable results.

Dr. Hesham Sadek:

Yeah. I mean, I was very happy that we received this paper to review, frankly I've been following that work for a long time since the first new England paper that came out and I'd like to congratulate you for an amazing work. I think this will change the field. First, how was this trial different from the first trial, other than the fact that it's multicenter, what would you say are the major changes that you made to the protocol and what you've learned since the first trial?

Dr. Emma Birks:

Yes, you're absolutely right. We did make some changes. So first of all, it was six sites instead of one site. I think it was very important to reproduce it in the US but we changed the protocol itself as well. The first trial had optimization of the LVAD speed, really just by echo looking at the reduction in the ventricle size. It had the aggressive medical regime was very similar except this time we increased the Losartan dose from 100 to 150 after the Hill's trial came out. The testing was very frequent in the original English Sheffield study, probably a little bit too frequent to be able to be adopted on a wide scale. So we tried to reduce it down a little bit. So we decrease the frequency of the low-speed echos. I think we had them at six weeks, four months, six months, nine months in a year.

Dr. Emma Birks:

And after that, we saw if they were already improving and started and only did them at a year to 18 months, if they were improving. And then we also cut down the number of exercise tests. So we didn't do the exercise test until the echo was already showing significant improvement. For two reasons, one, we didn't find it very reliable and two, it was just too much testing for the patient. So it was more of a confirmatory test. In fact, it wasn't a requisite for a pump explantation. We didn't do a left heart catheter, which we did before. Previously we tried to measure LVEDP, this time we decided which was enough. So we just did a right heart cath on and off pump. And we did that once the echo was improved as well. So we rationalized that a little bit. And then the other important thing was before in hayfield study, once we saw the ventricular size come down and injection fraction start to improve, we actually added in Clenbuterol, which was a Beta-2 agonist.

Dr. Emma Birks:

And the idea with that was to cause a kind of physiological hypertrophy so that when you took the pump out, the heart didn't just dilate. We were worried about atrophy at the heart on the pump long-term. So we did that to try and improve the durability of recovery. So the reason we left off this time was really the previous protocol was very good, but was very complicated. So we wanted to see what rate of recovery we could get just with the aggressive reverse remodeling, neurohormonal drugs, plus the aggressive testing and the optimum loading with the idea that later on, we could add on either Clenbuterol or something later to improve the durability of recovery, if the ability of recovery is not good enough, but actually so far it's proven to be pretty good because the study itself takes quite a long time. It was sort of to recruit them. We had an 18 month period than the follow-ups. It was already a multi-year study. So we wanted to establish a regime that many centers could use to try and promote recovery.

Dr. Hesham Sadek:

I want to follow up on that last point, because as you know, I've looked at some of these Heights as well in our center, and we looked at the results with you and Stavros and others. So the myocytes size is expected to change, decrease with unloading, right with sufficient unloading. So how would you prepare the Myocardium to take on the normal afterload if you are not going to induce by a beta agonist, for example,

Dr. Emma Birks:

What I would like to do in the future is try using the pump itself actually. Sometimes there's heart recovers, the heart shrinks and actually start opening their own valve and working in the heart. Of course, when you have the HeartMate one, actually, sometimes wasn't synchronous with the heart. So sometimes the heart will beat against the pump anyway. Once you go to the continuous flow pumps, you've got continuous unloading. So I think it'd be very interesting to intermittently turn down the pump speed and load the heart to work it before you take the pump out. So I would really like to do that. I think that might be the next interesting phase of the study to improve your ability to.. So I guess once you've got maximum reverse remodeling and improvement in function, you could just turn the pump speed down to let the valve open.

Dr. Hesham Sadek:

Do you think perhaps if you do that, you will increase the percentage of patients that can be explanted? Do you think that could be a factor in the percentage of patient that can be explained?

Dr. Emma Birks:

I think it might be, it might more improve the, to your ability to make sure we have for a long, good echo function afterwards.

Dr. Hesham Sadek:

That's great. So another question this was limited to not ischemic cardiomyopathy patients. Can you elaborate a bit on why not include, for example, revascularized ischemic cardiomyopathy patients.

Dr. Emma Birks:

Yeah, so we did that really just because we didn't want to change too much from the original protocol. We also stuck with one device because we thought if you have multiple pumps, multiple diagnosis, it does get hard to analyze in a multicenter trial. So we did that on purpose and we were always trying to simulate the bridge to transplant population in the age group too. But actually interestingly, most of the patients recruited in the trial were destination therapy patients in the end.

Dr. Emma Birks:

I think this could be done with ischemic cardiomyopathy. I think we don't have enough data on ischemic cardiomyopathy to know whether it does or it doesn't recover. So I don't think our results say that it's only known as ischemics. I think it just means we haven't studied ischemics sufficiently. Logically they might have more scarred. It might be harder to get such a good percentage to recover. I think all of us in our individual centers have seen a few and we've sort of seen the on pump echo improved, and we've tested them and then taken some out. But most of these cases are anecdotal. So I think that is another important study that needs to be done, obviously a large group of patients.

Dr. Hesham Sadek:

I agree. So given that they're not ischemic cardiomyopathy, do you know how many of them had genetic testing or what is the percentage of monogenic cardiomyopathys or how do you think these patients would respond to this protocol?

Dr. Emma Birks:

But if you had a familiar history and actually found it didn't make any difference, whether they recovered or not. I think some of us have personally seen actually those were the familial cardiomyopathy tend to recover more actually again, anecdotally. We published a people before looking at the Titin gene saying that that did recover. I think actually only five of these patients, 12% of them had a family history, but some of them recovered

Dr. Hesham Sadek:

One final question, as you know, I'm a basic scientist. So ultimately the question I'm going to ask, what do you think the mechanism is? Is it that these hearts are just in a vicious cycle of remodeling and validation, increased pressure, and you were sort of giving it a chance for actual structural reverse remodeling where you changed the geometry of the myocardium and perhaps rest of myocardium, allow for improvement of calcium cycling dynamics, or do you think, is something more exciting? Like three-generation for example.

Dr. Emma Birks:

Yeah, that's very interesting because I think the LVAD doesn't unload, so it shrinks the ventricles. I think it does improve the geometry and the dynamics. And then you use the drugs where they may have felt before you almost put them from class four, heart failure into class three with the bad to give that chance to work again. And then I think various cellular and fibrotic factors have been looked at and it's hard because there was so many factors have been looked at that. You were going to find some that go up and some that go down and what's important. But the impression I get overall is that you do get improvement, the matrix limits, the recovery on the fibrosis and the matrix. Whereas you do get improvements of myocardial function and cellular function. The cells will tend to reverse the dysfunction and it's really whether that happens or not. It's probably limited a lot by the matrix

Dr. Carolyn Lam:

That is amazing here. Hesham, I'm going to put you on the spot. Do you have your own hypothesis about this

Dr. Hesham Sadek:

Based on the work that they did initially in the new England paper, we did actually a small pathology study looking at cell cycle of cardiomyocytes from the core samples and from the explanted hearts post-transplant and we saw evidence of increased cardiomyocytes cell cycle in these patients along with decreased DNA damage and some metabolic remodeling as well with mitochondria. So, you can't really tell much from tissue whether you regenerated it or not, but as you know myocytes don't divide and this is the basis for the lack of spontaneous regeneration of the myocardium. So if this in fact removes the block to cardiomyocyte cell cycle, then this might be a regenerative therapy mechanism.

Dr. Carolyn Lam:

Well, this is amazing. I wish we had all day to discuss this more. I mean, this is the only place you can get a discussion that goes from clinical to basic signs and back to clinical. Thank you so much, Emma and Hesham for sharing today. Thank you audience for joining us today. You've been listening to circulation on the run on behalf of Greg as well. Don't forget to tune in again next week.

Speaker 1:

Program is copyright the American heart association, 2020.