A Score to Assess Mortality After Percutaneous Mitral Valve Repair

Background: Risk stratification for transcatheter edge-to-edge mitral valve repair (TEER) is paramount in the decision-making process for treating severe mitral regurgitation (MR). Objectives: This study sought to create and validate a user-friendly score (MitraScore) to predict the risk of mortality in patients undergoing TEER. Methods: The derivation cohort was based on a multicentric international registry that included 1,119 patients referred for TEER between 2012 and 2020. Score discrimination was assessed using Harrell's c-statistic, and the calibration was evaluated with the Gronnesby and Borgan goodness-of-fit test. An external validation was carried out in 725 patients from the GIOTTO registry. Results: After multivariate analysis, we identified 8 independent predictors of mortality during the follow-up (2.1 ± 1.8 years): age ≥75 years, anemia, glomerular filtrate rate <60 mL/min/1.73 m², left ventricular ejection fraction <40%, peripheral artery disease, chronic obstructive pulmonary disease, high diuretic dose, and no therapy with renin-angiotensin system inhibitors. The MitraScore was derived by assigning 1 point to each independent predictor. The c-statistic was 0.70. Per each point of the MitraScore, the relative risk of mortality increased by 55% (HR: 1.55; 95% CI: 1.44-1.67; P < 0.001). The discrimination and calibration for mortality prediction was better than those of EuroSCORE II (c-statistic 0.61) or Society of Thoracic Surgeons score (c-statistic 0.57). The MitraScore maintained adequate performance in the validation cohort (c-statistic 0.66). The score was also predictive for heart failure rehospitalization and was correlated with the probability of clinical improvement. Conclusions: The MitraScore is a simple prediction algorithm for the prediction of follow-up mortality in patients treated with TEER.