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Circulation on the Run


Mar 6, 2023

This week, please join author Xuerong Wen, Associate Editor Sandeep Das, and Guest Host Mercedes Carnethon as they discuss the article "Comparative Effectiveness and Safety of Direct Oral Anticoagulants and Warfarin in Patients With Atrial Fibrillation and Chronic Liver Disease: A Nationwide Cohort Study."

Dr. Carolyn Lam:

Welcome to Circulation on the Run, your weekly podcast summary and backstage pass of 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 Poly Heart Center at VCU Health in Richmond, Virginia.

Dr. Carolyn Lam:

Greg, I'm so excited about today's feature paper. It deals with the important condition where atrial fibrillation exists in patients with chronic liver disease and what do we do for anticoagulation in these patients. It's a comparative effectiveness and safety study of direct oral anticoagulants compared with warfarin in these patients. A huge, wonderful, important study that we're going to discuss. But before we get there, I'd like to tell you about some papers in this issue and I'd like you to tell me about some too. You got your coffee?

Dr. Greg Hundley:

Absolutely.

Dr. Carolyn Lam:

All right. I'll go first In this paper that describes a quantitative prognostic tool for the mitral valve prolapse spectrum and it's derived from the new mitral regurgitation international database quantitative or MIDA-Q registry, which enrolled more than 8,000 consecutive patients from North America, Europe, Middle East. And these were patients all diagnosed with isolated mitral valve prolapse or MVP in routine clinical practice of academic centers, all of which also did prospective degenerative mitral regurgitation quantification. The MIDA-Q score was calculated based on characteristics collected in routine practice combining the established MIDA score, which integrated guideline based markers of outcomes like age, New York Heart Association status, atrial fibrillation, LA size, pulmonary artery pressure left ventricular and systolic, I mentioned, and ejection fraction. Integrating that with scoring points based on the degenerative mitral regurgitation quantitation that is measuring effective regurgitant orifice and volume.

Dr. Greg Hundley:

Very interesting Carolyn. So a scoring system that combines clinical information with what we might assess with echocardiography like regurgitant volume or regurgitant orifice area. So how well did this mortality risk score perform?

Dr. Carolyn Lam:

So the new score was associated with an extreme range of predicted survival under medical management and that ranged from 97% to 5% at five years for the extreme score ranges. And it was strongly, independently and incrementally associated with long-term survival over all the markers of outcomes. So the authors concluded, and these by the way were authors led by Dr. Maurice Serrano from Mayo Clinic, Rochester, Minnesota. These authors concluded that the score should allow integrated risk assessment of patients with mitral valve prolapse to refine clinical decision making in routine practice and ultimately reduce degenerative mitral regurgitation under treatment.

Dr. Greg Hundley:

Wonderful description Carolyn. Well I'm going to switch to the world of electrophysiology, Carolyn. And so as you know, the Brugada syndrome is an inherited arrhythmia syndrome caused by loss of function variants in the cardiac sodium channel gene SCN5A and that occurs in about 20% of subjects. And these authors led by Dr. Dan Roden at Vanderbilt University School of Medicine identified a family with four individuals diagnosed with Brugada syndrome, harboring a rare missense variant in the cardiac transcription factor, TBX5, but no SCN5A variant. And upon identifying these individuals, their objective was to establish TBX5 as a causative gene in Brugada syndrome and to define the underlying mechanisms by which it would be operative.

Dr. Carolyn Lam:

Oh wow. So a new gene variant. So what was the relationship?

Dr. Greg Hundley:

Right Carolyn? So using induced pluripotent stem cell derived cardiomyocytes from members of the affected family, multiple electrophysiologic abnormalities were detected in these cardiomyocytes including decreased peak and enhanced late cardiac sodium current. In these cells these abnormalities were entirely corrected by CRISPR/Cas9 mediated editing of that TBX5 variant and transcriptional profiling and functional assays in unedited and edited pluripotent stem cell derived cardiomyocytes showed direct SCN5A down regulation caused decreased peak sodium current and that reduced PDGF receptor expression and blunted signal transduction to phosphoinositide-3-kinase. And interestingly, PDGF receptor blockade markedly prolonged normal induced pluripotent stem cell derived cardiomyocyte action potentials.

And also Carolyn interestingly in this study they did a separate analysis. It reviewed plasma levels of PDGF in the Framingham Heart Study and they found that they were inversely correlated with the QT corrected interval. And so Carolyn, these results established decrease SCN5A transcription by the TBX5 variant as a cause of Brugada syndrome and also reveal a new general transcriptional mechanism of arrhythmogenesis of enhanced late sodium current caused by reduced PDGF receptor mediated phosphoinositide-3-kinase signaling.

Dr. Carolyn Lam:

Wow. Wow, that's significant. Thanks Greg. So this next paper is also really important and could change the practice in the field of cardiac resynchronization therapy or CRT. You see, it suggests that the practice of what we do now, which is combining right bundle branch block with intraventricular conduction delay patients into a single non-left bundle branch block category when we select patients for CRT, that this may not be the way to go.

So let's go back a bit and remember that benefit from CRT varies with QRS characteristics and individual trials are actually underpowered to assess the benefit for relatively small subgroups. So the current authors led by Dr. Friedman from Duke University Hospital and colleagues, therefore performed a patient level meta-analysis of randomized trials of CRT to assess the relationship between QRS duration and morphology with outcomes.

Dr. Greg Hundley:

Very interesting Carolyn. So another wonderful paper from the world of electrophysiology in trying to understand optimal mechanisms to resynchronize the ventricle in patients with differing bundle branch blocks or intraventricular conduction delays. So what did they find?

Dr. Carolyn Lam:

They found that patients with intraventricular conduction delays and a QRS duration of 150 milliseconds or more, CRT was associated with lower rates of heart failure hospitalizations and all cause mortality. The magnitude of CRT benefit among these patients with the interventricular conduction delay of 150 milliseconds or more and those with the left bundle branch block of 150 milliseconds or more were similar.

In contrast, there was no clear CRT benefit for patients with a right bundle branch block of any QRS duration, although the authors could not rule out the potential for benefit at a markedly prolonged QRS duration.

So they concluded that the practice of combining right bundle branch block with intraventricular conduction delay patients into a single non-left bundle branch block category when we make patient selections for CRT is not supported by the current data. And in fact, patients with an intraventricular conduction delay of 150 milliseconds or more should be offered CRT as is done for patients with a left bundle branch block of 150 milliseconds or more.

Dr. Greg Hundley:

Wow, Carolyn, so really interesting point. No clear CRT benefit for patients with right bundle branch block regardless of the QRS duration. Well we've got some other articles in the issue. I'll describe a couple from the mail bag. There's a Research Letter from Professor Lassen entitled "Risk of Incident Thromboembolic and Ischemic Events Following COVID-19 Vaccination Compared with SARS-COV2 Infection." Also Bridget Kuhn has a wonderful Cardiology News piece entitled "Collaborative Care Model Helps Heart Failure Patients Meet End-of-Life Goals."

Dr. Carolyn Lam:

There's an exchange of letters between Doctors Donzelli and Hippisley-Cox regarding that risk of myocarditis after sequential doses of COVID-19 vaccine, there's an AHA Update by Dr. Churchwell on continuous Medicaid eligibility, the lessons from the pandemic. There's an On My Mind paper by Dr. Parkhomenko on Russia's war in Ukraine and cardiovascular healthcare.

Wow, what an issue. Thanks so much, Greg. Shall we go on to the feature discussion?

Dr. Greg Hundley:

You bet.

Dr. Mercedes Carnethon:

Well welcome to this episode of Circulation on the Run podcast. I'm Mercedes Carnethon, associate editor of the journal Circulation and Professor and Vice Chair of Preventive Medicine at the Northwestern University Feinberg School of Medicine.

I'm very excited to be here today with Xuerong Wen and Sandeep Das, my fellow associate editor here at Circulation to talk about a wonderful piece by Dr. Wen and colleagues from the University of Rhode Island. So welcome this morning Xuerong and thank you so much for sharing your important work with us.

Dr. Xuerong Wen:

Thank you Dr. Carnethon. It was great meeting you all and I'm the Associate Professor of Pharmacoepidemiology and Health Outcomes at the University of Rhode Island. I'm happy to introduce my study to everyone.

Dr. Mercedes Carnethon:

Well thank you so much and thank you as well Sandeep for identifying this fantastic article and bringing it forth.

Dr. Sandeep Das:

Thanks Mercedes. It's great to be with you.

Dr. Mercedes Carnethon:

Great. Well let's go ahead and get into it. There's so much here to talk about. So Dr. Wen and colleagues studied the comparative effectiveness and safety of direct oral anticoagulants or DOACs and warfarin in patients with atrial fibrillation and chronic liver disease. So this is such an important topic. Can you tell us a little bit about what your study found?

Dr. Xuerong Wen:

So our study is a comparative effectiveness and the safety analysis using a national health administrative data from private health plans. So we compared the risk of hospitalized ischemic stroke, systemic embolism and major bleeding between DOACs and warfarin in patients with atrial fibrillation and chronic liver disease. So we also had to had compare to these primary outcomes between apixaban and rivaroxaban in the study population.

So our studies show that among patients with atrial fibrillation and chronic liver disease, DOACs as a class was associated with lower risk of hospitalization of ischemic stroke and systemic embolism and major bleeding, compared with warfarin. And when compared risk outcomes between individuals apixaban has lower risks as compared to rivaroxaban. So that's our study results.

Dr. Mercedes Carnethon:

Well thank you so much. This seems like such an important question. We hear a lot about DOACs and some of their risks as well as their considerable benefits. I think what leaves me the most curious is why did you choose to pursue this question and in particular in patients with both atrial fibrillation and liver disease. So why was the intersection of these two particular conditions of interest to your study team?

Dr. Xuerong Wen:

That's a great question. So the liver actually plays a central role in both the synthesis of coagulation factors and the metabolism of anticoagulant drugs. And the clearance of the anticoagulants in liver ranges from 20% to 100% for DOACs and warfarin. So in clinical practice anticoagulation abnormalities and elevated risk of spontaneous or unprovoked venous thrombotic complications have been reported in patients with liver disease. While these patients with cirrhosis were excluded from the clinical trials of DOACs and also population based, the real world experience is very limited. So that is why we initiated this retrospective cohort study and based on the real world data in this specific population.

Dr. Mercedes Carnethon:

Oh, thank you so much for explaining that. I definitely learned a lot and really enjoyed reading the piece. I think it was very well organized and well written and I know that our readership will appreciate it. It obviously stood out to you as well, Sandeep. Can you tell me a little bit about why you thought that this would be an excellent piece for circulation?

Dr. Sandeep Das:

Yeah, absolutely. Thanks for the question.

So in the broad field of what we call observational comparative effectiveness research, so basically that's using large observational data sets to try to answer important clinical questions and it's a really challenging thing to do. I mean we're all very familiar with the idea of using randomized trials to assess important clinical questions because of the structure of that design allows you to mitigate some of the effects of confounding. Here, it has to be done analytically. So what's the important factor that really drives you towards a great observational comparative effectiveness piece? So first the clinical importance. I feel a little guilty because I'm old enough to remember when warfarin was the only option available, but really as a clinician, or every patient, I really prefer DOACs over warfarin just for ease of use and lifestyle. So there's a huge sort of importance to the question.

Second, the patients with chronic liver disease were excluded from the larger RCTs and the DOAC trials. So really we don't have the answer to the question already. It's an important question. Obviously the bleeding risk is tied up with the liver, warfarin directly antagonizes vitamin K, so there's real questions about safety and so this is the perfect storm and then on top of it was a really well done and well executed study. So when this came across my desk, the very first thing I thought was not, "Is this something that we're interested?" But rather, "How do we make it better? How do we make it more useful to the reader?" This had me from hello.

Dr. Mercedes Carnethon:

Well thanks so much. We rarely have the opportunity when we read an article to be able to ask the authors questions. So Sandeep, I know that you had mentioned that you had some follow up questions as well.

Dr. Sandeep Das:

Yeah. So the real thought that I have then is would you argue based on this that we know enough that we should change our practice? And that do you feel comfortable advocating that people now prescribe DOACs to these patients?

Dr. Xuerong Wen:

I would say yes. Okay.

Although this is not a clinical trial, but our study is actually systematically compare the effectiveness and safety between DOAC users and also the warfarin users. And if you look at our table one, we compare with so many variables between these two users and we use the propensity score adjustment and we after propensity score weighting and the two control group almost balanced.

And I know right now FDA actually suggested that emulate the trial using the large real world data to do the emulated trial. So our study actually conducted is based on the large population using large data and we use the propensity score weighting to control all this potential compounding factors. Although there are still some limitations in this study. I think we mentioned that in the discussion section and we discussed all potential compounding factors that still may exist.

And also there are some misclassifications and out of all this limitations and we still found the two drugs performed differently in this specific population. So we feel that comfortable to say that a DOAC drug performs better than warfarin. And also I think based on other studies that based on the clinical trial in the general population, DOAC drug is performs much better than warfarin and considering that the clearance in liver for DOAC is less than warfarin. So plus all this information together, I think DOAC may be safer than wafarin in the patients with AF and chronic liver disease.

Dr. Sandeep Das:

Yeah, I would say that I agree that these data, even if you're skeptical about observational CT generally, which I admit that I tend to be, these are really reassuring data that at least the DOACs are... There's absolutely nothing that suggests that they're any worse than warfarin and all of the sort of soft indications for ease of use and patient happiness really would seem to favor DOACs. So I think this is the sort of rare observational CT paper that may actually change my practice.

Dr. Mercedes Carnethon:

I have a follow-up question, Xuerong, related to the design and as well your strategy to address differences between the groups. So inverse probability weighting is certainly a standard in the field to be able to manage differences between groups when you have a situation where can't, where it's not a randomized trial. Do you as well, and educate me, I admit I'm an epidemiologist whose methodological skills are sometimes challenged. Do you have the opportunity using this design and with inverse probability weighting to evaluate subgroup effects? So my specific question is were you able to determine whether or not these associations were similar based on age and gender in particular?

Dr. Xuerong Wen:

That's a great question. We did conducted a lot of subgroup study but not by age or gender. We conducted I think this study in a lot of subgroups using the propensity score weighting, but the subgroup that I think we did a subgroup like a patient with a different chronic liver disease. So that's what we did. And we also tested different methods inverse probability score weighting. So we did trimming and we used a different percentage of trimming and to see how that affect the study results. So we have done a lot of subgroup studies. We did not check the age and the gender, but that's a very good point. Maybe later, well I'll ask my student to do that.

Dr. Mercedes Carnethon:

Well, you're a good mentor. So I think that is a really certainly an appropriate approach. Sandeep, did you have additional questions?

Dr. Sandeep Das:

No, I wish I had thought of yours before you did. I think exactly the older age, women, racial ethnic groups that are underrepresented historically in trials. I think that that's really, again, the sweet spot of this observational research. We definitely, and NH definitely working on trying to increase enrollment of all these groups in our CTs. However, while we wait for that, I think that's exactly what we should be doing.

Dr. Mercedes Carnethon:

Well that's great. And Xuerong, you really alluded to really, I think what is one of my final questions related to what do you think based on what you have observed in this study, what do you see as the next steps in the research field for your team, your students, or other people who are carrying out this type of work?

Dr. Xuerong Wen:

Well, that's a great question. We currently have a couple of more manuscripts ongoing in this field, and we will continue conducting the comparative effectiveness and analysis to compare drugs head to head as well as developing and implementing new methodologies to this field. And we hope our study provides real world evidence for clinical decision making, prescribing anticoagulants to patients with atrial fibrillation and chronic liver disease. We also expect the physicians and researchers more and more value the real world data studies, especially when clinical trials are not feasible or ethical.

Dr. Mercedes Carnethon:

Well, thank you so much. That was such an excellent vision that you provided us with and we're just very grateful that you submitted this fantastic work to the journal Circulation. I know that our readers will enjoy really digging in. The podcast is meant as a teaser to bring you to the journal so that you can read about this wonderful work by Dr. Wen and colleagues. So again, thank you. I'm Mercedes Carnethon, joined with my associate editor partner here, Dr. Sandeep Das. And thank you very much for spending your time with us today, Dr. Wen.

Dr. Xuerong Wen:

Thanks for this great opportunity to disseminate my study with us, thank you.

Dr. Sandeep Das:

Thanks Mercedes.

Dr. Mercedes Carnethon:

Thank you for joining us for this episode of Circulation on the Run.

Dr. Greg Hundley:

This program is copyright of the American Heart Association 2023. The opinions expressed by speakers in this podcast are their own and not necessarily those of the editors or of the American Heart Association. For more, please visit ahajournals.org.