Incidence and factors associated with mitral valve reoperation in patients undergoing surgery for mitral regurgitation: A nationwide cohort study

Background: When patients undergo surgery for mitral regurgitation, risk of reoperation is of concern. Aims: To examine the incidence and factors associated with mitral reoperation following surgery for mitral regurgitation according to type of surgery. Methods: Patients undergoing first-time surgery for mitral regurgitation, 1996-2021, were identified from nationwide registries. According to index surgery, the population was categorized into 1) mitral repair; 2) mechanical prostheses; 3) bioprostheses. Patients were followed from discharge with a maximum of 15 years of follow-up and cumulative incidence of reoperation was examined. Multivariable Cox analysis was used to examine factors associated with reoperation. Results: We identified 6958 patients: 4624 with mitral repair (72 % male, median age 66), 1250 with mechanical prosthesis (52 % male, median age 59), and 1084 with bioprosthesis (57 % male, median age 74). Cumulative incidence of reoperation was 7.3 % for repair (median 7.2 years follow-up), 6.1 % for mechanical prostheses (median 10.9 years follow-up), and 7.1 % for bioprostheses (median 4.5 years follow-up). Within first year, 22.6 % of reoperations were preceded by infective endocarditis. In long-term follow-up, bioprosthetic replacement was associated with a higher reoperation rate, while increasing age, male sex and mechanical prosthesis were associated with lower reoperation rate. Conclusions: In patients operated for mitral regurgitation, reoperation was infrequent at approximately 7 % for all intervention types during a maximum of 15-year follow-up. In adjusted analysis, bioprosthetic replacement was associated with a higher rate of reoperation, while increasing age, male sex and mechanical prosthesis was associated with a lower rate of reoperation.