Long-Term Outcomes of Mechanical Mitral Valve Replacement: A Comparison of Four Valve Types

TL;DR

This study compared four mechanical mitral valve types over the long term and found that valve type had little impact on outcomes, with patient factors and valve size being more important.

Contribution

A novel comparison of four mechanical mitral valve types using a competing risk regression model to assess long-term clinical and echocardiographic outcomes.

Findings

The composite endpoint incidence at 10 years ranged from 7% (ATS) to 14% (On-X), but valve type was not significantly associated with outcomes.

Patient factors like coronary artery disease and peripheral artery disease were significant predictors of adverse events.

All valve types were associated with favorable left ventricular remodeling, with no significant survival differences between groups.

Abstract

Background: The choice of mechanical prosthesis for mitral valve replacement (MVR) is critical, yet data comparing long-term outcomes across different valve types are still needed. This study aimed to compare the long-term clinical and echocardiographic outcomes of four distinct mechanical mitral valve prostheses. Methods: We retrospectively analyzed 431 patients who underwent mechanical MVR between 2009 and 2022 with one of four valve types: Carbomedics (n = 112), Bicarbon (n = 176), ATS (n = 89), or On-X (n = 54). A competing risk regression model was used to identify predictors of a composite endpoint (valve thrombosis, reoperation, stroke, pulmonary embolism, and major bleeding), accounting for all-cause mortality. Longitudinal echocardiographic data were analyzed using linear mixed-effects models. Results: The median follow-up was 62 months. The cumulative incidence of the composite endpoint at 10 years was 14% for the On-X valve, 12% for the Bicarbon valve, 9.5% for the Carbomedics valve, and 7% for the ATS valve. After adjusting for confounders, the type of valve prosthesis was not significantly associated with the composite endpoint. Significant predictors of adverse events included coronary artery disease (Sub-distribution Hazard Ratio [SHR] 2.70, p = 0.023), peripheral artery disease (SHR 6.29, p = 0.007), and smaller valve size (SHR 0.87, p = 0.037). No significant difference in overall survival was observed between the groups (log-rank p = 0.904). All valve types were associated with favorable LV remodeling. The Carbomedics group showed the greatest reduction in left ventricular end-diastolic diameter, likely reflecting regression to the mean given the larger baseline ventricular dimensions in this group. Conclusions: The type of mechanical mitral valve did not significantly influence long-term thromboembolic and bleeding events or overall survival. Patient-specific factors and valve size were the primary determinants of adverse outcomes. The observed differences in ventricular remodeling may warrant further investigation.

Figures