Long-term outcomes of mitral valve replacement in dialysis patients: evidence from a nationwide database

Background: To compare the late outcomes between mechanical and bioprostheses after isolated mitral valve replacement (MVR) in dialysis-dependent patients. Methods: A nationwide propensity-matched retrospective cohort study was conducted involving dialysis patients who underwent primary mitral replacement between 2001 and 2018. Ten-year postoperative outcomes were compared between mitral bioprosthesis and mechanical prosthesis using the Cox proportional hazard model and restricted mean survival time (RMST). Results: The all-cause mortality was 20.8 and 13.0 events per 100 person-years, with a 10-year RMST of 7.40 and 7.31 years for bioprosthesis and mechanical prosthesis, respectively. Major bleeding was the most common adverse event for both bioprosthesis and mechanical prosthesis, with an incidence rate of 19.5 and 19.1 events per 100 person-years, respectively. The incidence of valve reoperation was higher among those who received bioprosthesis (0.55 events per 100 person-years). After 1:1 matching, the all-cause mortality was 15.45 and 14.54 events per 100 person-years for bioprosthesis and mechanical prosthesis, respectively. The RMST at 10 years was comparable between the two groups after matching (5.10 years for bioprosthesis vs. 4.59 years for mechanical prosthesis), with an RMST difference of -0.03. Further, no difference was observed in the incidence of major adverse valve-related events between bioprosthesis and mechanical valves. However, bioprosthesis was associated with a higher incidence of mitral valve reoperation among all major adverse events (RMST difference -0.24 years, 95% CI -0.48 to -0.01, P=0.047). Conclusions: This study found no association between valve selection and long-term survival outcomes in dialysis patients after MVR. However, bioprosthetic valves may be associated with a slightly higher incidence of reoperation, while other valve-related adverse events, including major bleeding and stroke, were comparable between the two types of prostheses.