The Hamburg TranscathEteR Mitral Valve REplacement RegiStry (HERMES) is a prospective clinical cohort registry aiming to gather follow-up information on short- and long-term outcome of patients with mitral valve disease that undergo transcatheter mitral valve replacement (TMVR) screening. In particular, long-term durability and function of implanted bioprosteses is of utmost interest for both patients and clinicians. Moreover, this study aimes to investigate and compare the different treatment strategies patients undergo after successful or unsuccessful screening for TMVR.