Early and long-term results of minimally invasive mitral valve surgery through a right mini-thoracotomy approach: a retrospective propensity-score matched analysis

BACKGROUND: Minimally invasive mitral valve surgery (MVS) via right mini-thoracotomy has recently attracted a lot of attention. Minimally invasive MVS shows postoperative results that are comparable to those of conventional MVS through the median sternotomy as per various earlier studies. METHODS: Between 2000 and 2016, a total of 669 isolated mitral valve procedures for isolated mitral valve regurgitation were performed. A propensity score-matched analysis was generated for the elimination of the differences in relevant preoperative risk factors between the cohorts and included 227 patient pairs. Only degenerative mitral valve regurgitation was included. The aim of our study was to examine if the minimally MVS is superior to the conventional approach through sternotomy based on a retrospective propensity-matched analysis. The primary endpoints were early mortality and long-term survival. The secondary endpoints included postoperative complications. RESULTS: The in-hospital mortality rate was significantly higher within the conventional sternotomy cohort (3.1%, n = 7 vs 0.4%, n = 1 for the minimally invasive cohort; p = 0.032). The incidence of stroke and exploration for bleeding was comparable. In contrast, the necessity for dialysis was significantly lower in the minimally invasive cohort (p = 0.044). Postoperative pain was not significantly lower in the minimally invasive MVS cohort (p = 0.862). While patients who underwent minimally invasive MVS experienced longer bypass and cross-clamp times, their lengths of stay in the intensive care unit and in the hospital, did not differ from the conventionally operated collective (p = 0.779 and p = 0.516), respectively. The mitral valve repair rate of 81.1% in the minimally invasive cohort was significantly superior to that of the conventional approach, which was 46.3% (p < 0.0001). The one-, five-, and 10-year survival rates were significantly higher in the minimally invasive cohort compared to the conventional approach (96%, 90%, and 84% vs. 89%, 85%, and 70%; log rank p = 0.004). CONCLUSION: Despite prolonged cardiopulmonary bypass and cross-clamping times, the minimally invasive MVS may be considered a safe approach that is equivalent to standard median sternotomy with lower early mortality and superior long-term survival.