Risk-related clinical outcomes after minimally invasive mitral valve surgery: insights from the mini-mitral international registry (MMIR)

Abstract

Objective 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 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 analyze 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 EuroSCORE II. The observed to expected (O: E) 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 EuroSCORE II- in all risk categories (O: E 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 EuroSCORE II model overestimated the in-hospital mortality. We believe findings from the MMIR may assist surgeons and cardiologists in clinical decision-making and treatment allocation for patients with mitral valve disease.

Keywords: Minimally invasive mitral surgery, Mini Mitral International Registry (MMIR), Minimalli invasive cardiac surgery