Durability of Biological Valves Implanted in Aortic or Mitral Positions: A Nationwide Cohort Study

Background: Biologic prostheses are being increasingly used for aortic and mitral valve replacement (AVR and MVR). This study evaluated the long-term durability of bioprosthetic valves in the mitral and aortic positions, as no well-designed population-based studies have addressed this issue before. Methods: Using Taiwan's National Health Insurance Research Database, we compared biologic valve durability in the mitral and aortic positions in patients hospitalized between 2001 and 2017, with reoperation as the primary outcome. Both between-subject and within-subject designs were used, and the propensity score matching cohort (1:1 ratio) was created for the former. Results: We identified a total of 10,308 patients, 5462 of whom received AVR, 3901 received MVR, and 945 received double valve replacement. Both AVR and MVR cohorts had 2259 patients after matching. During a mean follow-up of 4.2 years (range, 1 day to 17.9 years), the reoperation rate in the MVR cohort (3.5%) was higher than that in the AVR cohort (2.6%) (hazard ratio 1.41; 95% CI, 1.01-1.98). A higher risk of all-cause death was observed in the MVR cohort (36.5%) than in the AVR cohort (32.6%) (hazard ratio 1.21; 95% CI, 1.10-1.34). Among patients receiving double valve replacement with the same prosthesis type, valves implanted in the aortic position were considerably less likely to require reimplantation. Conclusions: Bioprosthetic valve placement in the aortic position is associated with superior outcomes in terms of durability, long-term mortality, and perioperative morbidity. Developing novel interventions and enhancing valve durability would expand bioprosthesis use for valve replacement.