Circulation August 23, 2016 Issue

Circulation on the Run

Carolyn: 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.

In just a moment, we are going to be discussing the feature paper on results of the RE-LY trial in patients with valvular heart disease. Yes, you heard me right, this means dabigatran versus warfarin in patients with atrial fibrillation and valvular heart disease. You need to listen to this discussion with first author Dr. Michael Ezekowitz, but first here is a summary of this week's issue.

In the first study, Dr. Norby and colleagues from the School of Public Heath University of Minnesota assessed trajectories of cardiovascular risk factors and the incidence of atrial fibrillation over 25 years in the ARIC study or the Atherosclerosis Risk in Communities Study. They first assessed the trajectories of cardiovascular risk factors in more than 2,400 individuals with incident atrial fibrillation and more than 6,400 matched controls. Next, they determined the association of those risk factor trajectories with the incidence of new atrial fibrillation among more than 10,500 individuals free of atrial fibrillation at baseline.

The main finding was that stroke, myocardial infarction and heart failure risk increase steeply during the time close to diagnosis of atrial fibrillation. All cardiovascular risk factors were elevated in atrial fibrillation cases compared to controls more than 15 years prior to the diagnosis. A trajectory analysis showed not only the presence of the risk factors such hypertension and obesity, but also their duration which was more informative in determining the risk of atrial fibrillation compared to a one time clinical measurement.

Finally, they identified diverse and distinct trajectories for the risk factors findings that carry implications for the different roles of different risk factors in the pathogenesis of atrial fibrillation. The findings of this very significant study also highlight the need to establish preventive strategies that address risk factors decades before atrial fibrillation diagnosis.

The next study is by first author Dr. van der Valk and corresponding author Dr. Strauss from the Academic Medical Center in Amsterdam. These authors aimed to better understand the underlying mechanisms responsible for atherogenicity of lipoprotein a or LPa. The authors achieved this aim by a combination of three approaches. First, in vivo magnetic resonance imaging using 18F-FDG PET/CT and SPECT to measure atherosclerotic burden, arterial wall inflammation and monocyte trafficking to the arterial wall. Secondly, ex vivo analysis of monocytes using facts analysis, inflammatory stimulation assays and trans endothelial migration assays. Third, in vitro studies on monocytes using an in vitro model for trained immunity.

Their main findings were that, firstly, individuals with elevated LPa had increased arterial wall inflammation in vivo. Secondly, that monocytes from these individual remain in a long lasting activated state ex vivo, and finally, that LPa elicited a pro-inflammatory response in healthy monocytes in vitro, an effect that was markedly attenuated by removing or inactivating oxidized phospholipids on LPa.

In summary, this study nicely shows that LPa induces monocyte trafficking to the arterial wall and mediates pro-inflammatory responses through its oxidized phospholipid content. The clinical implications are therefore, that oxidation's specific epitope targeted therapy using for example specific antibodies as single gene antibodies may bear clinical potential to modulate the arthrogenic impact of LPa.

The final study is from first author Dr. Mazen, and corresponding author Dr. Ouzounian from Toronto General Hospital and University of Toronto in Ontario, Canada. These authors sought to compare the long term outcomes of patients undergoing the Ross procedure compared to mechanical aortic valve replacement in a propensity match cohort study of 208 pairs followed for a mean of 14 years.

They found long term survival and freedom from re-intervention were comparable between the Ross procedure and mechanical aortic valve replacement. Of note however, the Ross procedure was associated with improved freedom from cardiac and valve related mortality, as well as a significant reduction in the incidence of stroke and major bleeding. This paper provides important evidence that supports continued used of the Ross procedure in properly selected young adult patients in specialized centers.

What this means is having experienced surgical teams dedicated to mastering the technique and committed to carefully following up the patients for possible late complications. This and more is discussed in a provocative editorial by Dr. Schaff from Mayo Clinic Rochester, Minnesota who provocatively entitled his editorial 'The Ross Procedure: Is it the Preferred Procedure or Double, Double Toil and Trouble?'

Those were all summaries, now for our featured paper.

I am so excited to be joined from all over the world to discuss the featured paper today, and that is on the comparison of dabigatran versus warfarin in patients with atrial fibrillation and valvular heart disease. To discuss this first we have, first and corresponding author, Dr. Michael Ezekowitz from the Sidney Kimmel Medical College at Thomas Jefferson University and Lankenau Medical Center in Philadelphia, as well as from the Cardiovascular Research Foundation in New York. Welcome Michael.

Michael: Thank you very much.

Carolyn: Michael, you're calling from South Africa aren't you?

Michael: I am indeed.

Carolyn: That's wonderful. We're very honored to have Dr. Shinya Goto Sensei, Associate Editor of Circulation from Tokai University Japan. Hello Shinya.

Shinya: Hello Carolyn, thank you very much for your invitation to such an excited podcast. I enjoy podcast every week.

Carolyn: I love this and it is extremely exciting and the most global discussion that we have had so far, with calling in Japan and Singapore and South Africa. Indeed it's because we're discussing a very important problem globally. Michael first, when we talk about the RE-LY trial and the NOAC trials, we're always associating them with non-valvular atrial fibrillation, and yet your topic is discussing valvular heart disease from RE-LY. Can you please start by clarifying that?

Michael: I think the reason we wrote this paper is that there is a misunderstanding of the patient populations that was studied in all the NOAC trials because they were characterized as having non-valvular atrial fibrillation. That's only partially true because in all the trials, patients with mechanical heart valve and hemodynamically significant mitral stenosis were excluded, and yet there were many patients with valvular disease that were included. In the RE-LY trial which is the focus of this particular paper, 25% of the patients had some form of valvular disease that were recruited into the study. So the term non-valvular is misleading.

Carolyn: That is such an important clarification, and it's an issue that I see a lot in Singapore. Frankly, lots of patients with atrial fibrillation have some valve disease even if you exclude prosthetic valves, significant mitral stenosis or valvular heart disease requiring intervention. We're very clear not that this is the patient population you're referring to. Shinya, I want to bring you into this. I see lots of these patients, how about you?

Shinya: The same. Majority of patients have valvular heart disease, small mitral regurgitation is very common. We are excluding only clinically overt mitral stenosis and basically mechanical heart valve in all the newest trials. As Michael pointed out, it is very important to correct misunderstanding. Non-valvular atrial fibrillation, we used in the clinical trial is all atrial fibrillation except clinical overt mitral stenosis and prosthetic for mechanical heart valve.

Carolyn: Exactly. A great foundation for us to get our understand right before we discuss the findings. Michael, could you please give us the top line result and tell us what do the results mean for your own clinical practice?

Michael: Basically, it means that the patients with valvular heart disease that were included in the trial, and these included patients with mitral regurgitation with was the most common lesion, mixed aortic valve disease, tricuspid regurgitation, and also it turned out that there were 192 patients that had mild mitral stenosis. Those with mitral stenosis were presumed to be rheumatic in ideology, and they did have a profile of having rheumatic heart disease, that there were more females, they were younger, there was a high incidence of heart failure and a high incidence of TIA and stroke.

The bottom line here is whether the patients had mild mitral stenosis or the other forms of valvular disease that I just mentioned, that they benefited in an identical fashion from the 150 milligram BID dose of dabigatran and the one 110 milligram BID dose of dabigatran as those patients without any valvular disease. The bottom line is that clinicians can use dabigatran with equal confidence in these patients with valvular disease as in patients without valvular disease.

Carolyn: Thank you Michael, that was very reassuring and something that is very clinically important. Shinya, I'm going to ask a different question. First, maybe your take on the findings, and secondly, what was it like handling this paper across the globe as the Associate Editor Managing this?

Shinya: That is a very important point. The past as Michael pointed out, this paper is very important to remind the clinician of non-valvular atrial fibrillation is not really non-valvular atrial fibrillation, and there is no difference between valvular atrial fibrillation except mitral stenosis and prosthetic valve. The result is similar to non-valvular atrial fibrillation in regard to the effect of dabigatran or by warfarin. That is the one point I have to assure. As a part, it is very important. We are now including many patients not limited in that North America, Europe. We are participating a huge number of patients from Asia. The results is applicable to the global level. We are now leading in that global evidence-based world and RE-LY is one of the good example for the global trial testing the hypothesis with [inaudible 00:13:58] over warfarin.

Michael made a very good summary of that, not only limited to RE-LY, he talked about as our trial like ARISTOTLE and the ROCKET trial. All of the NOAC trial include patient who is valvular heard disease, and the exclusion criteria is a little bit different. Michael beautifully summarized that difference in the table, in his paper. There is a strong intention to publish this paper integration from all the editorial of old member. This is a very nice paper.

Michael: He's been very kind, that's very nice. That's true. In fact, the results in RE-LY were compared in an indirect fashion with the other trials, ROCKET and ARISTOTLE, through have published similar papers on patients with and without valvular heart disease. Just in summary, the bottom line is that this finding in RE-LY is highly reproducible in the other two trials so this is an important finding that is reproducible and true of the three novel agents that had looked at this in detail.

The other point that was raised is that there were differences in the exclusion criteria in these trials, but at the end of the day, the Europeans and the Americans in terms of guidelines, had fairly similar recommendation. For instance in the United States, it was felt that all patients with valvular disease could be anti-coagulated with the novel agent unless they had rheumatic mitral stenosis, mechanical or bioprosthetic heart valves, or patients that had undergone a prior mitral valve repair. The emphasis was that all other patients could be included.

The Europeans differed slightly and that they agreed that mechanical prosthetic valve and moderate to severe mitral stenosis should be excluded, but they were somewhat more global in recommending inclusions of all other valvular conditions. There is a slight difference then between the European and the American recommendations and guidelines.

Carolyn: On that note of looking across the world at the guidelines and what these results mean, it really leaves me to congratulate you Michael on such an excellent paper, and Shinya for just managing this paper so well.

Michael: Thank you.

Shinya: Thank you very much for your invitation. Bye-bye.

Carolyn: You've been listening to Circulation on the Run. Thank you for joining us today.