Long Term Survival Following Mitral Valve Replacement by Preoperative Risk: Implications for Patient Selection.

Background: Mitral valve replacement (MVR) is recognized for its significant operative risks. This risk is commonly quantified with the Society of Thoracic Surgeons (STS) Risk Calculator. The present study aimed to investigate the long-term (5-year) predictive capabilities of the STS PROM in patients undergoing isolated MVR.

Methods: Patients undergoing isolated MVR at a high-volume mitral reference center from 2010-2023 were stratified by STS PROM (low: <3%, intermediate: 3-6%, and high/extreme: >6%). Primary endpoints were short-term (30-day) and long-term (5-year) mortality. Kaplan-Meier survival analysis was used to compare short- and long-term survival among risk stratified groups. Cox regression modeling was used to identify predictors of long-term survival.

Results: Of 1,444 of MVR patients, 855 patients underwent isolated MVR. The mean STS PROM for low, intermediate, and high/extreme-risk groups were 1.7%, 4.3%, and 12.7%, respectively. 30-day mortality was lower than predicted in the low (0.3%) and high/extreme-risk (10.9%) groups. 5-year survival was 90.8%, 75.5%, and 56.4% respectively. Kaplan-Meier survival analysis at 5-years identified significant long-term survival probability differences among the PROM groups, even after accounting for peri-operative risk (p<0.001). Preoperative dialysis (HR 1.70, 95% CI 1.05-2.73, p=0.03), hypertension (HR 1.71, 95% CI 1.13-2.59, p=0.011), and urgent operative status (HR 1.57, 95% CI 1.09-2.26, p=0.02) were among the characteristics associated with worse long-term survival.

Conclusions: Although predictive models may overestimate surgical risk at high volume mitral centers, the STS PROM correlates with 5-year mortality in isolated MVR. These findings may provide more specific risk stratification criteria, identifying patients best suited for operative intervention.