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Phase III MITRA.fr study: Percutaneous mitral valve repair improves mitral regurgitation but not outcome

ESC Congress News 2018 - Munich, Germany

First data from the recently completed MITRA.fr trial were presented yesterday by Professor Jean-Francois Obadia (Hopital Louis Pradel, Lyon, France) in a Hot Line session(1). “For the first time, we have high-level evidence relating to the safety and efficacy of a Mitraclip device in patients with severe secondary mitral regurgitation (SMR) and chronic heart failure,” he notes.

Interventional Cardiology
Valvular Heart Disease


JF-Obadia-esc-congress-news-2018.jpgProf. Obadia explains that, “SMR is a major prognostic factor in patients with chronic heart failure. While the condition can be corrected, we don’t currently know whether this offers significant clinical benefit and this is what the trial set out to investigate.”

Over a 3-year period, patients were recruited to the study from 37 French centres; after centralised echographic Core Lab assessment, 307 patients were randomised in a 1:1 ratio to percutaneous mitral valve repair (pMVR) with the Mitraclip system in addition to optimal medical treatment (OMT; intervention group; n=152), or to OMT alone (control group; n=152). The primary efficacy endpoint was a composite of all-cause death and unscheduled hospitalisation for heart failure at 12 months.

At baseline, patients (mean age 70 years; 74% males) were severely symptomatic despite OMT, with 67% being in New York Heart Association (NYHA) class ≥III. The mean left ventricular ejection fraction was 33% and the functional mitral regurgitation (MR) was severe, with a mean regurgitant orifice area of 31 mm2. Patients were considered by a heart team to be ineligible for surgery.

“The safety of the Mitraclip system was high,” says Prof. Obadia, “with no conversion to surgery and no procedural mortality. In addition, the rates of vascular complication (3.4%), tamponade (1.3%) and cardiac embolism/stroke (1.3%) were all acceptable.” The efficacy results also looked promising, he says. “The technical success of the procedure, according to Mitral Valve Academic Research Consortium criteria, was 96%. After 12 months, the MR was significantly reduced in the Mitraclip group, with 83% of MR ≤ grade 2 versus 0 at baseline.”

However, despite the apparent safety and efficacy of the Mitraclip, the results did not translate into improved outcomes when compared to a control group, reports Prof. Obadia.

“There was absolutely no benefit of the Mitraclip in terms of survival rate or risk of rehospitalisation for heart failure at 12 months and the primary endpoint was negative.”

obadia-esc-congress-news-2018.jpgProf. Obadia continues, “Based on the confirmation of our statistical hypotheses and a follow-up of at least 99%, we can be confident that this conclusion is very robust. Moreover, the negative results seen in the primary analysis were observed also in the per-protocol analysis and all sub-group analyses.” He goes on to say that, “The medical treatment in the two groups was very good and in accordance with recommendations. A similarly improved clinical status was seen in both groups.”

“To sum up,” says Prof. Obadia, “we can say that Mitraclip was safe and effective at reducing the MR but that the primary composite endpoint, including all-cause death and unplanned hospitalisations for heart failure at one year, was not significantly different between groups.” He finishes with a plea, “If our conclusion on the primary endpoint seems robust, our analysis on a smaller sub-group of patients is more fragile. Therefore, more randomised studies are necessary to confirm our results and to define possible sub-groups of patients who could really benefit from mitral valve repair.”

1. Obadia J-F, et al. N Engl J Med 2018;August 27:doi:10.1056/NEJMoa1805374.

 

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Notes to editor

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ESC Congress is the world’s largest and most influential cardiovascular event contributing to global awareness of the latest clinical trials and breakthrough discoveries. ESC Congress 2018 takes place 25 to 29 August at the Messe München in Munich, Germany. Explore the scientific programme