Validation of a Risk Calculator for Surgical Repair of Primary Mitral Regurgitation

Risk estimation for cardiac procedures is essential for clinical decision-making. The aim of the study is to validate the recently introduced Society of Thoracic Surgeons (STS) risk score model for mitral valve repair (MVr) in degenerative mitral regurgitation (DMR) by investigating a large cohort undergoing minimally invasive MVr (MI-MVr).

A total of 1,081 consecutive patients with DMR undergoing non-emergent MI-MVr were retrospectively analyzed. The primary study endpoint was 30-day all-cause mortality (OM), while secondary endpoints were major morbidity and mortality (MM) and conversion-to-replacement (CONV). Predictive discrimination and calibration of the models were measured using receiver operating characteristic (ROC) analysis.

A 30-day mortality of 0.55% was observed in the study cohort. All risk scores were significantly higher in non-survivors. Like existing risk models, the intention-to-treat-OM (ITT-OM) model was predictive for OM (OR: 2.078, 95% CI: 1.324-3.621; p = 0.001), but its discriminatory ability was limited based on ROC analysis. EuroSCORE II showed the best discriminatory performance for mortality among the investigated models. Furthermore, second cross-clamping and CONV were independent predictors of OM (OR: 26.2, 95% CI: 4.3-160.0; p < 0.001 and OR: 12.8, 95% CI: 1.8-89.2; p = 0.010). The ITT-MM and ITT-CONV models demonstrated an acceptable discriminatory ability for predicting operative MM and CONV.

The ITT-based risk model was validated in our study cohort undergoing MI-MVr for DMR, showing only limited discriminatory performance for mortality, while the EuroSCORE II demonstrated better discrimination for mortality despite systematic overestimation. This is the first report validating the recently introduced model. However, further studies with larger cohorts are needed to overcome the limitations of the present study.