5-Year Prospective Evaluation of Mitral Valve-in-Valve, Valve-in-Ring, and Valve-in-MAC Outcomes: MITRAL Trial Final Results.

Background: The MITRAL (Mitral Implantation of Transcatheter Valves) trial is the first prospective trial to evaluate the safety and feasibility of balloon-expandable aortic transcatheter heart valves in patients with failed surgical bioprostheses or annuloplasty rings and severe mitral annular calcification treated with mitral valve-in-valve (MViV), valve-in-ring (MViR), or valve-in-mitral annular calcification (ViMAC).

Objectives: The aim of this study was to evaluate 5-year outcomes among these patients.

Methods: A multicenter prospective study was conducted among patients at high surgical risk at 13 U.S. sites. Patients underwent MViV (n = 30), MViR (n = 30), or ViMAC (n = 31) and were followed annually for 5 years. Kansas City Cardiomyopathy Questionnaire scores were obtained at baseline and follow-up visits. Echocardiograms were analyzed at independent core laboratories.

Results: A total of 91 patients underwent transcatheter mitral valve replacement (February 2015 to December 2017). The mean age was 74.3 ± 8.9 years. At 5-year follow-up, the lowest all-cause mortality was observed in the MViV group (21.4%), 94.7% of patients were in NYHA functional class I or II, and the mean mitral gradient was 6.6 ± 2.5 mm Hg. The MViR and ViMAC groups had higher all-cause mortality (65.5% and 67.9%), most survivors were in NYHA functional classes I and II (50% and 55.6%), and mean mitral gradients remained stable (5.8 ± 0.1 and 6.7 ± 2.5 mm Hg). Significant improvements in Kansas City Cardiomyopathy Questionnaire scores were observed when all 3 arms were pooled.

Conclusions: MViV, MViR, and ViMAC procedures were associated with sustained improvement of heart failure symptoms and quality of life among survivors at 5 years. Transcatheter heart valve function remained stable in all 3 groups. Patients treated with MViV had excellent survival at 5 years, whereas survival was lower in the MViR and ViMAC groups, consistent with underlying disease severity. Patients with more residual mitral regurgitation had higher mortality.