Propensity-matched analysis of minimally invasive mitral valve repair using a nationwide surgical database

The aim of this study was to compare the cases of minimally invasive mitral valve surgery (MICS-mitral) performed using right mini-thoracotomy (RT) with those performed using median sternotomy (MS).

Between 2008 and 2012, 6137 patients underwent isolated mitral valve repair at 210 institutions and were registered in the Japan Adult Cardiovascular Surgery Database. We compared 756 who underwent MICS-mitral via RT to 5381 MS patients and performed a one-to-one matched analysis based on the estimated propensity score.

The in-hospital mortality was similar between both groups (RT vs. MS: 0.5 vs. 1.1%). Although the incidence of postoperative stroke, renal failure, and prolonged ventilation was similar, the number of patients with mediastinitis was greater in the MS group (RT vs. MS: 0 vs. 0.7%, p < 0.01). Reexploration for bleeding was more frequent in the RT group (RT vs. MS: 2.9 vs. 1.4%, p < 0.01). Mortality and morbidity occurred at a higher rate in low-volume institutions. The propensity analysis showed that the operation-related times were significantly longer in the RT group, while the length of hospital stay was shorter. In a propensity analysis of patients <60 years of age, there was no in-hospital mortality.

MICS-mitral via RT was successful without compromising the clinical outcomes. Although the operation time and postoperative bleeding should be improved, an RT approach is safe in appropriately selected patients, especially those <60 years of age or treated in a high-volume center.