Endoscopic mitral valve surgery: picture from the real world-sub-analysis from the Mini-Mitral International Registry.

Background: In the field of minimally invasive mitral valve surgery (MVS), recent technical and technological advances have made endoscopic approaches increasingly popular. However, enthusiasm for endoscopic cardiac surgery has not translated into routine clinical usage likely due to the perceived complexity of the technique and the lack of robust supporting evidence. This study aims to evaluate operative results, and assess the overall effectiveness of endoscopic approaches in current surgical practice using data from the Mini-Mitral International Registry (MMIR). Methods: This is a retrospective multicenter cohort study based on data from the MMIR, a collaborative effort including 7,957 patients who underwent minimally invasive mitral procedures. For this analysis, patients who did not receive a full endoscopic approach were excluded. Clinical and procedural outcomes were defined according to Mitral Valve Academic Research Consortium (MVARC) standards. Primary outcome measures included the rate of valve repair, in-hospital mortality, and the incidence of postoperative complications. Logistic regression was applied to assess the multivariable association between covariates and in-hospital mortality. Results: Between 2015 and 2022, 2,563 patients underwent full endoscopic mitral surgery [median age 64 years; interquartile range (IQR), 53-73 years]. The etiology of mitral disease was degenerative in 70.5% of patients, functional in 13.7%, rheumatic in 6.6%, endocarditis in 3.3%, failure of previous mitral surgery in 3.8% and failure of previous transcatheter procedure in 1.2%. Mitral valve repair was performed in 2,107 cases (82.2%) and valve replacement in 439 (17.1%). A conversion to full sternotomy was required in 1.7% of cases. The overall in-hospital mortality rate was 2.5% (n=63), with a stroke rate of 1.1% (n=27). These were 1.7% and 0.8%, respectively, in patient who underwent isolated MVS. Risk analysis revealed that patient comorbidities and clinical status, rather than the technical aspects of the endoscopic approach, predominantly determined operative outcomes. Subgroup analysis of patients with degenerative mitral valve disease (n=1,800) revealed a younger cohort (62 years) with a low-risk profile (EuroSCORE II 1.1%). The valve repair rate was 94.9%. Overall, in-hospital mortality and stroke rates were 1.4% and 0.6%, respectively. Among patients who underwent valve repair, 98.8% had no or mild regurgitation at discharge. Conclusions: Endoscopic MVS is an effective technique for managing a broad range of mitral valve diseases, with excellent valve repair outcomes. The technique demonstrated satisfactory operative mortality and morbidity, even in high-risk patients and complex valve anatomies. Future studies should focus on long-term outcomes and the development of training programs to facilitate wider implementation.