COMMENTARY

The Latest on MitraClip From ESC 2019

Prof Bernard Prendergast

Disclosures

September 04, 2019

This transcript has been edited for clarity.

Welcome to Paris. My name is Bernard Prendergast, I'm an interventional cardiologist from London, UK. And I'm here at the ESC meeting, the annual congress gathering cardiologists from around the world, digesting a year's progress in cardiology. And specifically in my field, a year's progress in heart valve disease.

Two thousand and nineteen has been a leap year for heart valve disease, with progress on many fronts.

Mitral Regurgitation

We've been digesting in particular the implications of the device trials in secondary or functional mitral regurgitation and their implication for everyday clinical practice.

It's almost 1 year to the day since the findings of the MITRA-FR trial were presented here and published simultaneously by Jean-François Obadia, and colleagues from France. And within 1 month of that presentation last August/September, there were further emerging data from a US-based study, the COAPT trial, looking at a similar group of patients using the same device, the MitraClip (Abbott) edge-to-edge repair device.

Whilst for many years the paradigm of treatment for secondary mitral regurgitation had focused around medical treatment, with or without cardiac resynchronisation, for the first time we had randomised control trial evidence, looking at the role of device transcatheter treatment options.

Radically Different Findings

And the dilemma faced by the medical community 1 year ago was that the trials demonstrated radically different findings. The MITRA-FR study examining all comers with secondary mitral regurgitation and randomising them to the choice of medical treatment, with or without MitraClip repair.

And the COAPT trial based in the US looking at a similar patient study albeit with rather more rigorous inclusion criteria.

The problem was that the French-based study, MITRA-FR, produced a neutral result with no apparent benefits of MitraClip implantation, compared with the COAPT trial, which demonstrated devastatingly positive findings, with a dramatic reduction in hospitalisation for heart failure, the primary endpoint of the trial, but also major benefits for patients across a range of secondary outcomes, including mortality.

So the dilemma that has been pored over by the interventional cardiology and heart failure community in the 12 months since has been how to synthesise these two apparently similar trials with very different outcomes.

And it’s some comment that in fact 17 editorials have been written on the subject in the last 12 months giving some illustration to the uncertainty that has arisen in response to the results, and how we accommodate these and project them into everyday clinical practice.

Key Differences

The first important point to make is that although the trials are superficially similar they differ in several important characteristics. The first relates to patient selection and the echocardiographic inclusion criteria.

The criteria differed on either side of the Atlantic reflecting different definitions of severe mitral regurgitation, adjudicated by the American College, and the American Heart Association in the US, and the European Society of Cardiology here in Europe.

And as a consequence of those different definitions, the COAPT population was a patient with more severe mitral regurgitation, but less severe left ventricular dilatation.

Conversely, the patients in MITRA-FR were patients with more moderate mitral regurgitation, and arguably more severe left ventricular disease. Perhaps it's therefore not a surprise that a mitral-based intervention, MitraClip edge-to-edge repair, produced more beneficial effects in the COAPT trial.

The second major difference was related to optimisation of medical treatments. We've known for many years, if not decades, that medical treatment is associated with better outcome in these patients. We're talking about treatment with beta-blockers, with neurohormonal inhibition using ACE inhibitors, aldosterone antagonists etc.

And in the different trial protocols, in COAPT, patients could not be enrolled until they were already on maximal tolerated guideline adjudicated medication. Whereas in MITRA-FR, patients were enrolled and then their treatment was maximised after randomisation and after a MitraClip edge-to-edge repair procedure had been undertaken.

The third major difference relates to the technical outcomes of the procedures, perhaps reflecting the learning curve and the fact that enrolment in COAPT finished after MITRA-FR. The technical execution of the MitraClip procedure in the US-based study was arguably better than in France, with better acute outcomes, greater use of multiple clips, and greater reduction in mitral regurgitation at 1 year follow-up.

Open Discussions

So bringing all these results together, we were able at this meeting to have very open discussions between the different professional associations, and also reflect on the fact that the 2 year outcomes of MITRA-FR were presented, demonstrating no change at 2 years, and bringing the data up to speed as it were with the 2 year outcomes of COAPT.

So these trials remain very different. They have important echocardiographic and clinical differences in the characteristics of the patients enrolled. And it's the responsibility of the community now to use the results of these studies to guide future practice.

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