A Protocol Investigation Comparing Transcatheter Repair with the Standard Surgical Procedure for Secondary Mitral Regurgitation

<b>Background:</b> Secondary mitral regurgitation (SMR) is characterized by a pathological process impacting the left ventricle (LV) as opposed to the mitral valve (MV). In the absence of structural alterations to the MV, the expansion of the LV or impairment of the papillary muscles (PMs) may ensue. A number of technical procedures are accessible for the purpose of determining the optimal resolution for MR. Nevertheless, there is a dearth of rigorous data to facilitate a comparative analysis of MV replacement, MV repair (including subvalvular repair), and transcatheter mitral valve interventions (TMV-Is). The objective of this investigation is to evaluate and compare the efficacy and clinical outcomes of transcatheter mitral valve repair (TMV-r) utilizing the edge-to-edge mitral valve repair (TEER) procedure in comparison to conventional surgical mitral valve interventions (S-SMVis) in patients with secondary mitral regurgitation. <b>Methods and analysis:</b> A consortium of five cardiac surgery institutions from four European states and Japan have joined forces to establish a multicenter observational registry, designated TEERMISO. Patients who underwent technical procedures for SMR between January 2007 and December 2023 will be enrolled consecutively into the TEERMISO registry. The investigation team evaluated the comparative efficacy of replacement and repair techniques, utilizing both the standard surgical methodology and the transcatheter intervention. The primary clinical outcome will be the degree of left ventricular remodeling, as assessed by the left ventricular end-diastolic volume index, at 10 years. The forthcoming research will assess a variety of secondary endpoints, among which all-cause mortality will be the primary endpoint. Subsequent assessments will be made in the following order: functional status, hospitalization, neurocognition, physiological measures (echocardiographic assessment), occurrence of adverse clinical incidents, and reoperation. <b>Ethics and dissemination:</b> The multicenter design of the database is anticipated to reduce the potential for bias associated with institutional caseload and surgical experience. All participating centers possess an established mitral valve protocol that facilitates comprehensive follow-up and management of any delayed mitral complications following replacement surgery or surgical repair of the secondary mitral regurgitation. The data collected will provide insights into the impact of diverse surgical approaches on standard mitral valve surgery and TEER. This will facilitate the evaluation of LV remodeling over the course of long-term post-procedural follow-up. <b>Trial Registration:</b> ClinicalTrials.gov ID: NCT05090540; IRB ID: 202201143.