Transcatheter mitral valve implantation in rigid mitral annuloplasty rings: Potential differences between complete and incomplete rings.

Transcatheter mitral valve implantation (TMVI) has been performed in high-risk and inoperable patients for degenerated mitral bioprostheses (TMVIinV) and failed annuloplasty rings (TMVIinR). TMVIinR is more challenging compared to TMVIinV because of the differences in dimensions, shapes, and contours between rings and valves. In this report, we present two clinical cases of TMVIinR that were treated by trans-septal implantation of a balloon-expandable prosthesis. In TMVI cases with an incomplete ring, the ring will be stretched out toward its anterior and commissural side, and the open side of the ring will increase in width. The ring may not transform in line with the shape of the transcatheter heart valve (THV) and an interspace can develop between the THV and the ring at the commissural side, resulting in significant paravalvular regurgitation. Our experience suggests that the circumferential completeness of the rings may be an important factor to consider when planning a TMVIinR.