Transcatheter mitral valve replacement in a complex mitral annular calcification anatomy.

Background: Transcatheter mitral valve replacement (TMVR) is emerging as a feasible alternative to conventional surgical intervention in patients at high surgical risk, also those with severe mitral annular calcification (MAC). However, the presence of a previously implanted self-expanding transcatheter aortic valve prosthesis introduces considerable technical difficulties, especially due to the risk of left ventricular outflow tract obstruction. Case summary: To our knowledge, it is among the very few reported cases of combined percutaneous interventions with a self-expanding valve in the aortic position and a balloon-expandable valve in the mitral position. During the procedure, circulatory arrest occurred, followed by the development of cardiac tamponade; both complications were rapidly and effectively managed. Subsequently, the patient experienced acute heart failure caused by a residual, procedure-related defect in the atrial septum, which required closure via a percutaneous approach. Discussion: This case underscores the significant technical and clinical challenges associated with TMVR in the setting of MAC, particularly in patients with a pre-existing self-expanding aortic bioprosthesis. Intra-procedural complications, including circulatory arrest, cardiac tamponade, and procedure-related atrial septal defect, required rapid treatment and solution.