Cardiac Imaging in Structural Valve Clinical Trials: Secondary Mitral Regurgitation

Transcatheter mitral valve interventions including transcatheter edge-to-edge repair and transcatheter mitral valve replacement have emerged as vital therapies for secondary mitral regurgitation (SMR) in patients at high or prohibitive surgical risk. Advanced multimodality imaging is central to patient selection, procedural guidance, and outcome assessment. This review delineates the roles of echocardiography (transthoracic and transesophageal), cardiac computed tomography, and cardiac magnetic resonance in structural valve clinical trials. We examine the imaging criteria used for patient selection in current transcatheter mitral valve intervention trials for SMR, as well as the key imaging findings following device implantation. Important lessons from advanced imaging in these trials include: (1) atrial and ventricular SMR (A-SMR and V-SMR) represent distinct disease morphologies that have led to divergent management recommendations; (2) the results of V-SMR trials can be explained by differences in regurgitant severity relative to left ventricular size; (3) numerous exclusionary anatomic considerations for transcatheter mitral valve replacement have limited trial enrollment and clinical applicability; (4) immediate postdevice imaging parameters predict outcomes; and (5) surrogate imaging end points at follow-up are associated with clinical outcomes.