Patient selection, data collection, endpoints
This study was conducted in accordance with the “Guidelines for reporting mortality and morbidity after cardiac valve interventions”[13]. Overall methods and study design for this cohort of patients have been previously reported[14]. Briefly, this was a retrospective cohort study of consecutive patients undergoing MVr at a single institution between February 2004 and July 2015. The follow-up period closed July 2016. Prior to 2004, minimally invasive mitral repair was not routinely done and therefore these cases were excluded. MVr was defined as MV reconstruction with or without an annuloplasty ring. Patients who underwent MV annuloplasty alone (without valve reconstruction), were excluded. Patients undergoing concomitant cardiac procedures were included. The institutional review board of the University of Southern California Health Sciences Campus approved this study (HS-15-00509) and waived the requirement for patient consent. The senior author performed over 85% of the total procedures, and nearly 100% of the minimally invasive procedures.
Patients were divided into two groups based on the operative approach to MVr (Group 1 - MVr via small right anterior thoracotomy, RAT; Group 2 – MVr via full sternotomy, ST). Baseline characteristics and perioperative outcomes were identified through our institutional database. The primary endpoints were mortality, need for MV reoperation, and the progression of mitral regurgitation (MR). Follow up TTEs were obtained at the discretion of the physician. MR was coded 0 to 4 based on echocardiogram reports (0 = none, 1 = trace, 2 = mild, 2.5 = mild-to-moderate, 3 = moderate, 3.5 = moderate-to-severe, 4 = severe). Progression of MR was defined as worsening of MR by more than 2 grades.