Risk of Surgical Mitral Valve Repair for Primary Mitral Regurgitation

Background: Risk estimation for surgical intervention is an essential component of heart team shared decision-making. However, current mitral valve (MV) surgery risk models used in practice lack etiologic or procedural specificity. The purpose of this study was to establish a comprehensive method for assessment of operative risk of MV repair of primary mitral regurgitation (MR).

Methods: A novel etiology and procedure-specific algorithm identified 53,462 consecutive (July 2014 to June 2020) intention-to-treat MV repair patients with primary MR from The Society of Thoracic Surgeons Adult Cardiac Surgery Database. Risk models were fit for 30-day operative mortality, mortality and/or major morbidity, and conversion-to-replacement (CONV). As-treated mortality and morbidity models were derived separately.

Results: Event rates for mortality (n = 619; 1.16%), mortality plus morbidity (n = 4746; 8.88%), and CONV (n = 3399; 6.36%) were low. Mortality was higher in CONV patients vs repair (3.18% vs 1.02%). All event rates were lower with increasing program volumes. The mortality risk model had excellent discrimination (AUC: 0.807) and calibration and confirmed very low mortality risk for isolated MV repair for primary MR, with mean mortality risk of 1.16% and median of 0.55% (interquartile range: 0.30%-1.17%) with 90th and 95th percentiles 2.48% and 3.99%, respectively. The mortality risk was <0.5% in patients <65 years of age, with 97% of the total population across age groups having a risk of <3%. Only 1 in 4 patients age 75 or older had >3% estimated risk of mortality.

Conclusions: This etiologic and procedure-specific risk model establishes that the contemporary mortality risk of MV repair for primary MR is <1% for the vast majority of patients.