Minimally Invasive Mitral Valve Repair Through Right Minithoracotomy　― 11-Year Single Institute Experience ―

BACKGROUND: Although minimally invasive mitral valve repair (MIMVR) is increasingly being performed, only a few clinical studies from Japanese institutions have been reported. METHODS AND RESULTS: From 2006 to 2017, 387 consecutive patients (135 females, mean age 56±13 years) underwent an initial isolated MIMVR through a right minithoracotomy. The mitral etiology was degenerative in 348, functional in 22, and endocarditis in 13 cases. Repair techniques included leaflet resection/plication in 280, chordal reconstruction in 109, and annuloplasty alone in 24 patients, and concomitant procedures included tricuspid valve repair and atrial fibrillation ablation in 70 (18.1%) and 78 (20.2%), respectively. Hospital mortality rate was 0.26%; 2 patients (0.5%) required intraoperative conversion to a median sternotomy. Perioperative morbidity included stroke (1.3%), reoperation for bleeding (0.8%), prolonged ventilation (0.5%), and permanent pacemaker implantation (2.1%). The transfusion rate was 14.7% and median ventilation time was 4 hours. Overall 5-year survival was 96.9%. For patients with degenerative mitral regurgitation (MR), the 5-year freedom from reoperation or severe recurrent MR, and freedom from ≥moderate MR were 94.7% and 82.2%, respectively. Repair for anterior mitral leaflet prolapse and the initial 30 cases were associated with higher occurrence of recurrent MR. CONCLUSIONS: MIMVR can be performed safely with low levels of mortality and morbidity, and provides sufficient repair durability. A learning curve exists in terms of repair durability, especially for anterior mitral leaflet repair.