Jan 24, 2022
Please join authors Christopher Granger and Anthony Carnicelli, as well as Associate Editor & Editorialist Shinya Goto as they discuss the article "Direct Oral Anticoagulants Versus Warfarin in Patients With Atrial Fibrillation: Patient-Level Network Meta-Analyses of Randomized Clinical Trials With Interaction Testing by Age and Sex" and accompanying Editorial "Patient Level Meta-Analysis: End of the Era for DOAC Developmental Trial in AF Patients?"
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 Nam, 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.
Dr. Carolyn Lam:
Greg, I'm so excited about our feature discussion today. It is about DOACs versus warfarin in patients with atrial fibrillation, a really important patient-level network meta-analysis of randomized control trials with interaction testing by agent six. So you can already tell something very, very clinically relevant and important discussed by not only the authors, but our dear associate editor and editorialist.
Dr. Carolyn Lam:
Okay. You just got to tune in, but first I'm going to start us off with some coffee, as well as a description of this first paper in today's issue. The 2018 AHA ACC multi-society cholesterol guidelines states that statin therapy may be withheld or delayed among intermediate risk individuals in the absence of coronary artery calcium.
Dr. Carolyn Lam:
However, two traditional cardiovascular risk factors associate with incident atherosclerotic cardiovascular disease events among individuals with zero coronary artery calcium over the long term? Well, this is the question that investigators decided to answer in today's paper and they're led by Dr. Virani from Baylor College of Medicine in Houston, Texas.
Dr. Carolyn Lam:
They studied 3,416 individuals with coronary artery calcium score of zero at baseline from the MESA study, which is a prospective cohort study of individuals free of clinical atherosclerotic cardiovascular disease at baseline. Among these individuals with zero coronary artery calcium, cigarette smoking, diabetes and hypertension were found to be independently associated with incident atherosclerotic cardiovascular disease events over long-term follow up.
Dr. Greg Hundley:
Ah, very interesting. Another piece of information relating to how we might use coronary artery calcium scores in, it sounds like, a high-risk patient population. So, Carolyn, what's the take-home message here?
Dr. Carolyn Lam:
Well, even if individuals have a coronary artery calcium of zero, if they are current smokers, if they have diabetes melitis or hypertension, initiation and long-term use of statin therapy, along with a heart healthy lifestyle and risk factor modification may still be warranted as part of the patient/clinician risk discussion.
Dr. Greg Hundley:
Very interesting Carolyn. Well, I've got a clinical study to tell you about. And, Carolyn, as you know, obesity and diabetes are associated with a higher risk of heart failure and the inner relationships between different measures of adiposity, including overall obesity, central obesity, fat mass, and diabetes status for heart failure risk, are not well established.
Dr. Greg Hundley:
And so this investigative group, led by Dr. Ambarish Pandey, from UT Southwestern Medical Center, looked at the ARIC, the visit five in ARIC and CHS, the visit one, and cohorts together, and they were obtained from the NHLBI BioLINCC. They were harmonized and pooled for the present analysis, excluding individuals with prevalent heart failure.
Dr. Greg Hundley:
So using multi-variable adjusted fine-grade model models were created to evaluate the associations of body mass index, waist circumference, and fat mass with risk of heart failure in the overall cohort, as well as among those with, versus without, diabetes at baseline.
Dr. Greg Hundley:
And the population attributable risk of overall obesity with BMI greater than 30 kilograms per meter squared, abdominal obesity with waist circumference greater than 88 and 102 centimeters in women and men, respectively, and high fat mass above the sex-specific median for incident heart failure, was evaluated among participants with and without diabetes.
Dr. Carolyn Lam:
Ooh, I'm so in interested in this topic. So what did they find, Greg?
Dr. Greg Hundley:
Right, Carolyn. So a large study, it included 10,387 participants, about 53% from ARIC, 25% had diabetes, and the median age was 74 years. And higher levels of each adiposity measure were significantly associated with higher heart failure risk. The population-attributable risk percentage of overall obesity, abdominal obesity, and high fat mass for incident heart failure was higher among participants with diabetes versus those without diabetes.
Dr. Greg Hundley:
And so, Carolyn, we can conclude from this research that higher BMI, higher waist circumference and higher fat mass, are strongly associated with greater risk of heart failure among older adults, particularly among those with prevalent diabetes.
Dr. Carolyn Lam:
So, so nicely done. Thank you, Greg. Well, the next paper talks about common ancestry-specific ion channel variants and how they predispose to drug-induced arrhythmias. Now, we know that multiple reports associate the cardiac sodium channel gene Scn5a variants, and these are the specific variants, S1103Y and R1193Q, with Type 3 congenital long QT syndrome and drug-induced long QT syndrome.
Dr. Carolyn Lam:
These variants are, however, two common in ancestral populations to be highly arrhythmogenic at baseline. The S1103Y allele frequency, for example, is 8.1% in Africans and the R1193Q is 6.1% prevalent in East Asians. So the investigators, led by Dr. Roden from Vanderbilt University Medical Center in Nashville, Tennessee, and colleagues, determined the effect of the S1103Y variant on QT intervals among 1,479 Africans from a large electronic health record with no confounding medications or diagnosis of heart disease.
Dr. Carolyn Lam:
Now, while both the specific variants generated increased late sodium current, baseline action potential durations in cardiomyocytes from induced pluripotent stem cells carrying these variants were unexpectedly normal. The re-polarizing potassium current, IKR, was markedly increased in these induced pluripotent stem cells with the variants, accounting for normal baseline action potential duration but, with exposure to an IKR blocker, they displayed exaggerated action potential duration prolongation and after depolarizations.
Dr. Greg Hundley:
Wow, Carolyn, interesting. So tell us, what are the clinical implications of this really exciting research?
Dr. Carolyn Lam:
Yeah. So here's the take-home message. These common ancestry-specific variants do not affect baseline re-polarization, despite generating an increased late sodium current. So the authors propose that increased re-polarizing potassium current, IKR, serves to maintain normal re-polarization, but increases the risk of manifest QT prolongation with IKR blocking in these variant carriers. So we need to be aware of that and, further, these findings highlight the need to include ancestral diversity in genomic and pharmacogenomic studies.
Dr. Greg Hundley:
Oh, wow. Beautifully described, Carolyn. I really appreciate that. Just excellent discussion. Well, Carolyn, my next paper comes to us in an investigation regarding doxorubicin or anthracycline-associated induced cardiotoxicity. So, Carolyn, multiple pharmacogenetic studies have identified the synonymous genomic variant rs7853758 and the intronic variant rs885004 and SLC28A3 as statistically associated with a lower incidence of anthracycline-induced cardiotoxicity.
Dr. Greg Hundley:
However, the true causal variant, or variance, of this cardioprotective mechanism at this locus, the role of SLC28A3 and other solute carrier transporters in anthracycline-induced cardiotoxicity and the suitability of solute carrier transporters as targets for cardioprotective drugs has not been investigated.
Dr. Carolyn Lam:
Wow. Got it. So what did these investigators do and find, Greg?
Dr. Greg Hundley:
Right. So Paul Burridge and his colleagues at Northwestern University found that the patient-specific cardiomyocytes recapitulate the cardioprotective effect of the cGAS-identified SLC28A3 locus, and the authors functionally confirmed for the first time, the role of SLC28A3 in doxorubicin-induced cardiotoxicity.
Dr. Greg Hundley:
And a novel genetic variant, the rs11140490, is the potential causal variant in the SLC28A3 cardioprotective locus. And finally, Carolyn, the solute carrier transporter inhibitor desipramine protects against doxorubicin-induced cardio toxicity through decreasing the intracellular uptake of doxorubicin into the heart.
Dr. Carolyn Lam:
Wow. That is a lot of data. Could you summarize it for us, Greg?
Dr. Greg Hundley:
Right, Carolyn. So these investigators provide two potential therapeutic options to attenuate doxorubicin-induced cardiomyopathy, either repurposing FDA-approved desipramine, or therapy with long non-coding RNA SLC28A3-AS1. Also, Carolyn, they propose that a simple clinical test to detect the presence of rs11140490 can be used to predict that a patient will be less likely to experience doxorubicin-induced cardiomyopathy, and that, perhaps with future clinical trials, it may be possible for these patients to be treated with a longer duration, that is a higher accumulative dose of doxorubicin, to enhance the efficacy of their chemotherapy.
Dr. Carolyn Lam:
I love the way you took that home for us. Thank you, Greg. Well, also in today's issue is a Research Letter by Dr. Chen on multifaceted spacial and functional zonation of cardiac cells in an adult human heart.
Dr. Greg Hundley:
Right, Carolyn. And Professor Constantine has a Letter to the Editor entitled Pravastatin Versus Placebo in Pregnancies at High Risk of Term Preeclampsia. Well, Carolyn, how about we get onto that feature article and learn about DOACs versus warfarin in this very large network meta-analysis?
Dr. Carolyn Lam:
Yes, yes, yes. Let's go, Greg. Thanks.
Dr. Greg Hundley:
Welcome, listeners, to our feature discussion today. And we're very fortunate. We're going to review the utility of DOACs in patients with atrial fibrillation. And we have with us two of the authors of this original research, Dr. Anthony Carnicelli from Duke University, and Dr. Chris Granger from Duke University.
Dr. Greg Hundley:
Additionally, we have with us our associate editor, Dr. Shinya Goto, from Japan. Welcome, gentlemen. Anthony, we'll start with you. Describe for us a little of the background information pertaining to your study and what was the hypothesis that you wanted to address?
Dr. Anthony Carnicelli:
Yeah, thanks so much, Greg, for having us here to discuss this. I started working in the DOAC space when I was a resident at Brigham and Women's Hospital with mentorship from Dr. Bob Guigliano there, and was really fortunate to connect with Dr. Granger when I came to Duke for a fellowship, and we had this unique opportunity to take data out of the four largest trials of anticoagulants in the atrial fibrillation, and take individual patient data from these international centers and combine them to form the combined AF database from which we did this analysis.
Dr. Anthony Carnicelli:
So a very unique opportunity here to have individual patient-level data from over 70,000 patients, and perform this analysis. And, really, what we aimed to do was to do the kind of highest quality meta-analysis using network meta-analysis methods to investigate the relative safety and efficacy of DOACs versus warfarin and a broad and diverse, but randomized, population of patients with atrial fibrillation.
Dr. Greg Hundley:
Very good. So you started to describe for us your study population and your study aligns. So tell us a little bit more, who were these patients, and then maybe specifically give us a little bit of the outline of your meta-analysis.
Dr. Anthony Carnicelli:
Yeah, so these were, again, a very broad patient group, but from kind of 10,000 feet, this was a population of patients with atrial fibrillation who were at risk of stroke, from CHADS score perspective. So there are some nuances from each of the included studies, of course, regarding the individual risk of stroke from one study to the next. But largely, as I mentioned, in patients with non-valvular atrial fibrillation randomized to either DOAC or warfarin.
Dr. Anthony Carnicelli:
And, from a method standpoint, we are fortunate at Duke and at DCRI, to have an expert in the network, meta-analysis methodology, whom we've worked with, Dr. Bonnie Huang, who helped to put together the analysis here and to proceed with this kind of network methodology.
Dr. Anthony Carnicelli:
And so, again, our goal was to evaluate the overall safety and efficacy of DOACs versus warfarin, but then also to dive into some specific subgroups, both from a categorical covariant perspective, and then also to evaluate some continuous covariants, specifically age, and to assess gender across the entire spectrum of continuous age in our population, which, of course is a unique opportunity in the individual patient-level data.
Dr. Greg Hundley:
And, Anthony, you had, gosh, it looks like over 70,000 patients in this particular analysis. Tell us a little bit about the results.
Dr. Anthony Carnicelli:
Yeah, so interesting, actually, and I agree that the biggest strength of our meta-analysis is the individual patient-level data and also the profound number of randomized patients included. So I think, from a high level, the most important results to highlight are the fact that there is a 19% relative risk reduction in stroke or systemic embolism among patients who are randomized to DOACs compared to warfarin, with an 8% reduction in all-cause death and a 55% reduction in intracranial hemorrhage.
Dr. Anthony Carnicelli:
So a massive reduction in the most feared complications of both atrial fibrillation and then also those associated with systemic oral anticoagulation. We also found a trend towards less bleeding in patients randomized to the standard-dose DOAC group, as well.
Dr. Greg Hundley:
Very good. Well, Chris, we're going to turn to you. What an exciting discovery here, and beautiful methodology. I wonder, in addition to what Anthony has shared with us, were there particular outcomes that were pertinent to men versus women or perhaps related to age?
Dr. Christopher Granger:
Yeah, Greg. So, again, we're proud of this as being really the state-of-the-art ability to evaluate safety and efficacy in this incredibly important population of patients with Afib and at risk for stroke, and to be able to dive into the subgroups and to the individual outcomes, even the less common outcomes. And one of the most striking things, and this really reinforces prior data, but with the greatest confidence of any study ever done, there was this 55% at reduction in intracranial hemorrhage and 19% reduction in total stroke and systemic embolism, really highlighting that these drugs are clearly better than warfarin, from reinforcing the guidelines.
Dr. Christopher Granger:
And the message with the subgroups is there was really a remarkable amount of consistency. And specifically in the older population where people are really concerned about anticoagulation, there was a clear and consistent major advantage of DOACs over warfarin. Men versus women, clear, clear, compelling benefit of DOACs over warfarin across each of these outcomes, including mortality, by the way, 8%. But highly statistically significant reduction in total mortality.
Dr. Christopher Granger:
A couple of the interesting ones, there was some effect modification. In other words, some evidence of an even greater benefit in patients who were not previously on a vitamin K antagonist or who had lower creatinine clearance, really important group, right? The renal impairment group.
Dr. Christopher Granger:
And then there was a greater benefit of lower risk of bleeding for patients with low body weight. And, in fact, the younger population, if anything, had a greater benefit with respect to less bleeding. And the bleeding is so important, Greg and Shinya, right? Because that's the major reason that people are not using anticoagulation, warfarin or DOACs, for this large population of patients who are untreated. And I hope this meta-analysis will be viewed as evidence that have really safe and effective treatments that are underused for this population that we're concerned about bleeding.
Dr. Greg Hundley:
Excellent. Thanks so much, Chris. Well, Shinya, you see a lot of papers come across your desk. What attracted you to this particular paper? And then can you help us put these results in the context with others that have evaluated the utility of DOACs in patients with atrial fibrillation?
Dr. Shinya Goto:
Thank you, Greg. Let me congratulate for Anthony and Chris and also group for conducting this great work. I mean, combine AF with amazing success for sharing the clinical trial database. So that all the four with a DOAC available is approved by each country based upon individual trial. Individual trial itself, large enough, right? Include more than 10,000 patient, but this time the [OSA 00:19:49] accumulated all four DOAC trial database together so that it is easy to say clinical trial data sharing provided robust evidence.
Dr. Shinya Goto:
But it is difficult, actually, to conduct it. I really commended OSA to conduct this success. So the data is predicted, I would say. Individual clinical trial itself shows lower risk of bleeding in DOAC as compared to warfarin. But this paper really provides the first time standard dose of DOAC reduce the risk of stroke and systemic embolism and death as compared to warfarin.
Dr. Shinya Goto:
So I really commented OSA. So this paper have a strong impact on the medical care. DOAC rapidly change the standard of care already. But superior efficacy was shown only in a few dose of DOAC, like 150 milligram BID of dabigatran, 60 milligram QD edoxaban, and five milligram apixaban. But this combined AF provides a stronger and a trustable robust evidence DOAC is better than warfarin.
Dr. Greg Hundley:
Very nice. Well, gentlemen, I want to turn back to you. I'll start with Anthony and then Chris, and then Shinya. Anthony, what do you think is the next study to be performed, really, in this space?
Dr. Anthony Carnicelli:
Well, it may be a bit of a pitch, but I mean, we have many opportunities in the combined AF data set to perform additional analyses, but I think that one of the most important next steps in this space that I'm most excited about is with respect to the newer oral anticoagulants that are coming down the pike.
Dr. Anthony Carnicelli:
For example, the Factor 11 inhibitor space. I mean, I think that there is another opportunity in the near future to potentially revolutionize the systemic anticoagulation space. And I think that data from combined AF could potentially be used to help continue moving the ball forward, again in the development of newer agents. So I think that's probably the thing that I'm most excited about in this space.
Dr. Greg Hundley:
Very good. And, Chris?
Dr. Christopher Granger:
Greg, I think there's so many unanswered questions and I think, as Tony points out, this highlights the fact that we know a lot, but there's a lot of unanswered questions. And those, some of the ones that I'm most interested in are low burden AFib, this AFib that we're detecting now with smart watches and devices, and what we do with that. And patients with renal impairment, including all the way down to renal failure, where those are relatively underrepresented, including in the combined AF data set.
Dr. Greg Hundley:
Very good. And, Shinya?
Dr. Shinya Goto:
Yeah. Yeah, Anthony and Chris talked about a little bit the plans to space, but I insist there is a lot of space that also could do with the combined AF database. We can expect a lot of sub-analysis, like you conducted as a continuous variable in this paper, but you can do that with eGFR as continuous variable, PMI as continuous variable. So we can expect a lot of sub-analysis. Probably, this is the end of publication from the individual DOAC development trial. You change the game with the combined AF data set.
Dr. Greg Hundley:
Very good. Well, listeners, we want to thank Dr. Anthony Carnicelli, Dr. Christopher Granger and our own associate editor, Dr. Shinya Goto, for bringing us this very interesting result from the meta-analysis that, compared to warfarin, DOACs have a more favorable efficacy and safety profile among patients with atrial fibrillation. Well, on behalf of Carolyn and myself, we want to wish you a great week and we will catch you next week on the run.
Dr. Greg Hundley:
This program is copyright of the American Heart Association, 2022. 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.