Valve-in-valve transcatheter transfemoral mitral valve implantation (ViV-TMVI): Characteristics and early results from a nationwide registry.

Background: Valve-in-valve transcatheter transfemoral mitral valve implantation (ViV-TMVI) is an emerging treatment alternative to reoperation in high-surgical risk patients with failed mitral bioprostheses.
Aim: We aimed to describe the characteristics of ViV-TMVI and evaluate its 30-day outcomes in the Polish population.
Methods: A nationwide registry was initiated to collect data on all patients with failed mitral bioprosthesis undergoing ViV-TMVI in Poland. This study presents the results of a 30-day clinical and echocardiographic follow-up.
Results: Overall, 27 ViV-TMVI procedures were performed in 8 centers up to May 2022 (85% from 2020 onwards). The mean (standard deviation [SD]) age was 73 (11.6) years with the median (interquartile range [IQR]) Society of Thoracic Surgeons score of 5.3% (4.3%-14.3%). Mean (SD) time between surgical implantation and ViV-TMVI was 8.2 (3.2) years. Failed Hancock II (29%) and Perimount Magna (22%) bioprostheses were most frequently treated. Mechanisms of failure were equally often pure mitral regurgitation or stenosis (both 37%) with mixed etiology in 26%. Balloon-expandable Sapien 3/Ultra valves were used in all but 1 patient. Technical success was 96.3% (1 patient required additional prosthesis). Mean (SD) transvalvular mitral gradient reached 6.7 (2.2) mm Hg and mitral valve area was 1.8 (0.4) cm2. None of the patients had moderate or severe mitral regurgitation with only 14.8% graded as mild. We achieved device success in 92.6% of patients (2 patients had mean gradient ≥10 mm Hg) and procedural success in 85.6%. There were no deaths, cerebrovascular events, or need for mitral valve surgery during the 30-day follow-up.
Conclusions: In short-term follow-up, ViV-TMVI is a safe and effective alternative for patients with failed mitral bioprosthesis at high surgical risk of re-operation. Longer observations on larger samples are warranted.