Is minimally invasive mitral valve surgery inappropriate for redo-surgery or elderly patients? -- Study of 55 consecutive cases following minimally invasive mitral valve replacement via right mini-thoracotomy

Background: Minimally invasive mitral valve surgery has been established as a routine procedure at our institution. In the present study, early and mid-term outcomes of patients who underwent minimally invasive mitral valve replacement (MIMVR), including redo-operations and elderly patients, during the 5-year post-surgery period were analyzed to review short-term morbidity and mortality, and mid-term results. Methods: Preoperative variables, intraoperative findings, and postoperative outcomes of MIMVR patients treated from January 2014 to November 2020 and prospectively stored in a database were reviewed. Survival and freedom from cerebrovascular events were evaluated using life tables and Kaplan-Meier analysis. Results: A total of 445 patients underwent minimally invasive mitral valve surgery during the study period, of whom 55 received mitral valve replacement (MVR), including 18 cases of redo-MVR and 10 elderly (≥80 years old) patients. Mean age at the time of surgery was 70.7±11.3 years. The number of patients who underwent conversion to a sternotomy was 0, while 30-day mortality was noted in one (2%). For all MIMVR cases, 1- and 5-year survival was 90.8±3.9 % and 76.5±7.1%, respectively. Furthermore, freedom from cerebrovascular events and anticoagulation-related complications was 94.3±3.2% and 84.2±6.3% at 1 and 5 years, respectively. In univariate analysis, independent predictors of hospital mortality and prolonged hospital stay included infectious endocarditis, while previous cardiac surgery and elderly status were not significant factors. Conclusions: MIMVR can be performed safely and effectively for redo-MVR and in elderly patients with very few perioperative complications. Early and mid-term outcomes in the present cohort were acceptable.