Transcatheter Mitral Valve Replacement in Valve-in-Valve, Valve-in-Ring, and Valve-in-Mitral Annular Calcification: A Case-Based Review

Transcatheter mitral valve replacement (TMVR) has emerged as a viable alternative to surgery in patients with failed mitral bioprostheses, annuloplasty rings, or native disease with mitral annular calcification (MAC). This case-based review explores the evolving TMVR landscape through three illustrative cases, emphasizing key aspects of preprocedural planning, technical features, and postprocedural management. Valve-in-valve (ViV) procedures remain the most predictable, with encouraging mid-term outcomes. In contrast, valve-in-ring (ViR) and valve-in-MAC (ViMAC) procedures pose greater challenges due to more complex baseline patient characteristics, anatomical intricacy, and higher procedural risk including valve embolization and paravalvular leak. Advances in dedicated TMVR systems and refined procedural strategies have begun to address these limitations, particularly for ViMAC. Continued progress in imaging, device design, and patient selection-supported by data from ongoing pivotal trials-will be essential to safely and effectively expand the benefits of TMVR to this anatomically and clinically high-risk population.