MITRAL Investigates TMVR in Native Mitral Valve Disease With Severe Mitral Annular Calcification

July 10, 2016—Results from the MITRAL multicenter global registry were published by Mayra Guerrero, MD, et al in Journal of the American College of Cardiology (JACC): Cardiovascular Interventions (2016;9:1361–1371).

The MITRAL study sought to evaluate the outcomes of the early experience of transcatheter mitral valve replacement (TMVR) with balloon-expandable valves in patients with severe mitral annular calcification (MAC) and reports the first large series from a multicenter global registry.

As noted by the investigators, the risk of surgical mitral valve replacement in patients with severe MAC is high, and there are isolated reports of successful TMVR with balloon-expandable valves in this patient population. 

As summarized in JACC: Cardiovascular Interventions, the investigators performed a multicenter retrospective review of clinical outcomes of patients with severe MAC undergoing TMVR. From September 2012 to July of 2015, 64 patients in 32 centers underwent TMVR with compassionate use of balloon-expandable valves. The patients’ mean age was 73 ± 13 years, 66% were female, and the mean Society of Thoracic Surgeons score was 14.4 ± 9.5%. The mean mitral gradient was 11.45 ± 4.4 mm Hg and the mean mitral area was 1.18 ± 0.5 cm².

The devices used were the Sapien valve (Edwards Lifesciences) in 7.8% of procedures, Edwards Sapien XT in 59.4%, Sapien 3 in 28.1%, and Inovare (Braile Biomedica) in 4.7%. Access was transatrial in 15.6%, transapical in 43.8%, and transseptal in 40.6% of procedures. 

Technical success according to Mitral Valve Academic Research Consortium criteria was achieved in 46 (72%) patients, primarily limited by the need for a second valve in 11 (17.2%). Six (9.3%) patients had left ventricular tract obstruction with hemodynamic compromise. Mean mitral gradient postprocedure was 4 ± 2.2 mm Hg, paravalvular regurgitation was mild or absent in all. Thirty-day all-cause mortality was 29.7% (cardiovascular, 12.5%; noncardiac, 17.2%); 84% of the survivors with follow-up data available were in New York Heart Association functional class 1 or 2 at 30 days (n = 25).

The study concluded that TMVR with balloon-expandable valves in patients with severe MAC is feasible, but may be associated with significant adverse events. This strategy might be an alternative for selected high-risk patients with limited treatment options, advised the investigators in JACC: Cardiovascular Interventions.