Survival after mechanical vs biological mitral valve replacement: Influence of age versus operative mortality score

BACKGROUND Although predicted risk of operative mortality (PROM) varies among patients, current guidelines favor bioprostheses for patients aged over 65 or 70. We compared survival after biological versus mechanical mitral valve replacement (MVR), and analyzed the effect of valve type on survival according to age versus PROM. METHODS From 1983 to 2020, 2092 consecutive patients undergoing isolated MVR were enrolled. Hazard ratios for survival between mechanical versus bioprostheses were compared as a function of age and PROM using Cox proportional hazards risk adjustment. Either inverse propensity weighting or propensity matching was used to further adjust for differences between biological versus mechanical groups. RESULTS In all inverse propensity weighted patients, PROM significantly interacted with the survival advantage of mechanical valves (P=0.004). Mechanical valves were associated with significant survival advantage at age 50 for PROM under 9%, at age 63 for PROM under 5%, and at age 70 for PROM under 3%. There was no significant mortality advantage for mechanical patients for STS PROM over 9% at any age or over age 70 at any PROM. CONCLUSIONS Contrary to some guidelines, mechanical MVR showed significant survival benefit in patients up to age 70 with low PROM, but survival benefit was not significant for PROM 9% or more at any age. Valve selection should be individualized considering both patient age and PROM in addition to other factors.