Transcatheter mitral valve replacement using transcatheter aortic valve implants in the mitral position: a UK multicentre experience

Background Transcatheter aortic valves in the mitral position (TAV-in-MV) are used in selected high-risk or inoperable patients with degenerated mitral bioprostheses, failed annuloplasty rings or severe mitral annular calcification. We aimed to describe outcomes of mitral valve-in-valve (MViV), mitral valve-in-ring (MViR) and valve-in-mitral annular calcification (ViMAC). Methods Consecutive patients undergoing TAV-in-MV across 12 UK centres were included. Technical success, complications, in-hospital mortality, all-cause mortality and symptomatic status were described for each cohort. Intercohort differences were considered exploratory and hypothesis-generating given the diverse patient-population. Results Among 184 procedures, 112 were MViV, 46 MViR and 26 ViMAC. Mitral Valve Academic Research Consortium (MVARC) technical success was 96%, 83% and 73%, respectively. Left ventricular outflow tract obstruction occurred in 0%, 9% and 23% and residual >2 grade paravalvular mitral regurgitation in 0%, 11% and 4%, respectively, in successful cases. In-hospital mortality was 4%, 7% and 21%. Median follow-up was 12, 12 and 11 months, respectively. Kaplan-Meier estimated 1-year all-cause mortality was 17%, 20% and 37%. At follow-up, 93% of MViV, 75% of MViR and 80% of ViMAC patients were in New York Heart Association (NYHA) classes I–II. Conclusion In this multicentre case series, MViV was associated with high technical success, low in-hospital mortality and symptomatic improvement during follow-up. MViR and ViMAC were performed less frequently and showed greater procedural complexity or adverse outcomes. Given their rarity, concentrating these procedures in experienced, high-volume centres or the use of proctoring may help maintain operator and team expertise to optimise patient outcomes.