Open Heart Mitral Valve Replacement Using Transcatheter Heart Valves for Severe Mitral Annular Calcification-A Literature Review.

Mitral annular calcification makes conventional mitral valve surgery extremely challenging and has led to growing interest in less invasive alternatives such as transcatheter mitral valve replacement. Alongside percutaneous approaches, some centers have explored open transatrial implantation of transcatheter heart valves in patients with heavily calcified annuli. This systematic review examines the current evidence on this hybrid "valve-in-MAC" technique, tracing its clinical evolution, technological refinements, patient outcomes, and ongoing debates. Key themes emerging from the literature include the adaptation of existing balloon-expandable and mitral-specific devices to the complex anatomy of calcified mitral annuli, the open transatrial approach as a safer alternative to extensive surgical debridement, and advances in imaging and device design aimed at reducing left ventricular outflow tract obstruction and paravalvular leak. Persistent uncertainties remain, particularly regarding patient selection, long-term valve performance, and comparisons with conventional surgical repair or replacement. Although open transatrial implantation appears technically feasible and provides favorable hemodynamic results compared with fully percutaneous procedures, reported 30-day mortality remains high (approximately 19-27%). This reflects the advanced age, frailty, and multiple comorbidities typical of this patient group rather than procedural shortcomings. Current evidence is limited, with few comparative studies and little data on valve durability. Future work should prioritize multicenter prospective registries and well-designed comparative studies to better define the role of this emerging salvage strategy.