Long-Term Results Following Repair for Degenerative Mitral Regurgitation - Analysis of Factors Influencing Durability

Background The majority of patients with degenerative mitral regurgitation (DMR) are amenable to reconstructive procedures. There is debate regarding factors that influence long-term durability with respect to repair technique, valve remodelling and progressive myxomatous change. Methods A total of 685 patients with DMR underwent mitral valve repair by a single surgeon between 1991 and 2011 with follow-up completed at 31 December 2016. Repair rate for patients undergoing surgery for DMR was over 90%. Mean age was 64 years (18-89) with 66.2% male, 47% NYHA class III-IV, and 20% had permanent atrial fibrillation (PAF). Major associated procedures were performed in 28% of patients (189); including coronary artery bypass graft (CABG) (127), aortic valve replacement (15), aortic root surgery (3) and tricuspid valve annuloplasty (61). Results Operative mortality (<= 30 days) occurred in four patients (0.58%). At 20 years, survival was 58%, freedom from reoperation was 90% and freedom from reoperation and non-operated recurrent MR >2+ (relapse) was 78%. Factors influencing survival were advancing age, left ventricular (LV) dysfunction (ejection fraction <60% or end systolic dimension >40 mm), New York Heart Association (NYHA) III-IV and PAF. Predictors of relapse were the degree of residual intraoperative mitral regurgitation (p < 0.001), anterior leaflet prolapse (p < 0.001) and the addition of a sliding annuloplasty in isolated posterior leaflet repair (p = 0.023). The majority of reoperations were for technical issues related to the original repair. A competent valve at 6 months to 3 years postoperatively predicted an excellent long-term result. Conclusion The great majority of degenerative mitral valves are repairable regardless of age with excellent long-term results achievable following surgery. Survival is reduced by significant symptoms, LV dysfunction and preoperative PAF. Repair is best performed before these features develop. Durability is largely dependent on the technical performance of the repair and degree of residual MR on the post-pump transoesophageal echocardiogram. We recommend surgery should be performed by surgeons specialising and skilled in mitral valve repair.