Risk-related clinical outcomes after minimally invasive mitral valve surgery: insights from the Mini-Mitral International Registry

OBJECTIVES: With the popularization of catheter-based mitral valve procedures, evaluating risk-specific differentiated clinical outcomes after contemporary mitral valve surgery is crucial. In this study, we assessed the operative results of minimally invasive mitral valve operations across different patient risk profiles and evaluated the value of EuroSCORE (ES) II predicted risk of mortality model for risk prediction, in the large cohort of Mini-Mitral International Registry (MMIR). METHODS: The MMIR database was used to analyse mini-mitral operations between 2015 and 2021. Patients were categorized as low (<4%), intermediate (4% to <8%), high (8% to <12%) and extreme risk (≥12%) according to ES II. The observed-to-expected mortality ratio was calculated for each risk group. RESULTS: A total of 6541 patients were included in the analysis. Of those, 5546 (84.8%) were classified as low risk, 615 (9.4%) as intermediate risk, 191 (2.9%) as high risk and 189 (2.9%) as extreme risk. Overall operative mortality and stroke rates were 1.7% and 1.4%, respectively, and were significantly associated with patient's risk. The observed mortality was significantly lower than expected-according to the ES II-in all risk categories (observed-to-expected ratio < 1). CONCLUSIONS: The present study provides an international contemporary benchmark for operative outcomes after minimally invasive mitral surgery. Operative results were excellent in low-, intermediate- and high-risk patients, but were less satisfactory in extreme risk. The ES II model overestimated the in-hospital mortality. We believe that findings from the MMIR may assist surgeons and cardiologists in clinical decision-making and treatment allocation for patients with mitral valve disease.