Long-term results after mitral valve surgery using minimally invasive versus sternotomy approach: a propensity matched comparison of a large single-center series.

Background: Mitral valve (MV) surgery has traditionally been performed by conventional sternotomy (CS), but more recently minimally invasive surgery (MIS) has become another treatment option. The aim of this study is to compare short- and long-term results of MV surgery after CS and MIS.
Methods: This study was a retrospective propensity-matched analysis of MV operations between January 2005 and December 2015.
Results: Among 1357 patients, 496 underwent CS and 861 MIS. Matching resulted in 422 patients per group. The procedure time was longer with MIS than CS (192 vs. 185 min; p = 0.002) as was cardiopulmonary bypass time (133 vs. 101 min; p < 0.001) and X-clamp time (80 vs. 71 min; p < 0.001). 'Short-term' successful valve repair was higher with MIS (96.0% vs. 76.0%, p < 0.001). Length of hospital stay was shorter in MIS than CS patients (10 vs. 11 days; p = 0.001). There was no difference in the overall 30-day mortality rate. Cardiovascular death was lower after MIS (1.2%) compared with CS (3.8%; OR 0.30; 95%CI 0.11-0.84). The difference did not remain significant after adjustment for procedural differences (aOR 0.40; 95%CI 0.13-1.25). Pacemaker was required less often after MIS (3.3%) than CS (11.2%; aOR 0.31; 95%CI 0.16-0.61), and acute renal failure was less common (2.1% vs. 11.9%; aOR 0.22; 95%CI 0.10-0.48). There were no significant differences with respect to rates of stroke, myocardial infarction or repeat MV surgery. The 7-year survival rate was significantly better after MIS (88.5%) than CS (74.8%; aHR 0.44, 95%CI 0.31-0.64).
Conclusion: This study demonstrates that good results for MV surgery can be obtained with MIS, achieving a high MV repair rate, low peri-procedural morbidity and mortality, and improved long-term survival.