Classification of primary mitral regurgitation using extramitral cardiac involvement in patients undergoing transcatheter edge-to-edge repair.

Background: An enhanced classification of primary mitral regurgitation (PMR) based on extramitral cardiac involvement may refine patient selection and optimize the timing of transcatheter edge-to-edge repair (TEER).

Aims: This study aimed to assess the prognostic significance of a recently established classification system that characterizes the extent of extramitral cardiac damage in patients undergoing TEER for PMR.

Methods: Consecutive PMR patients who received MitraClip implantation were categorized according to the presence of extramitral cardiac damage, determined through preprocedural echocardiography. The classifications included no damage or only left ventricular dilatation (group 0), left atrial involvement (group 1), right ventricular volume/pressure overload (group 2), right ventricular failure (group 3), or left ventricular failure (group 4). Cox-proportional hazard models were used to ascertain the impact of PMR groups on the primary composite outcome of all-cause mortality or rehospitalization for heart failure (HHF) over 2 years.

Results: In a cohort of 322 eligible PMR patients undergoing TEER (median age: 83 years; 41% female) between 2013 and 2020, the following distribution emerged: group 0 (10 patients, 3%), group 1 (96 patients, 30%), group 2 (117 patients, 36%), group 3 (56 patients, 18%), and group 4 (43 patients, 13%). Kaplan-Meier analysis demonstrated a significant decline in freedom from the primary outcome as group severity increased (log-rank p = 0.030). On multivariate analysis, the degree of extramitral cardiac involvement was significantly associated with the primary outcome (HR: 1.30; 95% CI: 1.02-1.67; p = 0.043), primarily driven by HHF.

Conclusions: This innovative classification system for PMR, based on extramitral cardiac involvement, carries significant prognostic implications for clinical outcomes following TEER. Integrating this classification system into clinical decision-making could enhance risk stratification and optimize the timing of TEER in these patients.