Is a Mechanical Valve a Better Option for Mitral Replacement in Elderly Patients with Longer Life Expectancy?

J. Choi¹, M. Bishawi², J. Gaca³, B. Zwischenberger², C. Milano³, K. Carr³, D. Glower^3
1Seoul National University Hospital, Seoul, Seoul-t'ukpyolsi ²Duke University, Durham, North Carolina ³Duke University Medical Center, Durham, North Carolina

Purpose: Although life expectancy and individual health status vary among patients, current guidelines favor bioprostheses in patients aged over 65. We compared survival after biological versus mechanical mitral valve replacement (MVR) in patients aged over 65 as a function of life expectancy after MVR.

Methods: A prospectively maintained database was used to identify consecutive patients aged 18 years or older undergoing mitral valve replacement between 1964 and 2020. During the 37- year study period, 4361 patients were enrolled. Propensity score-matched analyses were performed to compare the clinical outcomes between patients with a mechanical versus biological valve in all patients (OVERALL), in GROUP 1) all patients over 65 years, and in GROUP 2) patients over 65 years who survived more than 5 years after surgery. The time-varying Cox analysis was used to explore whether the effect of biological versus mechanical prostheses on survival. The survival duration dependent hazards of postoperative survival was modeled using a natural cubic spline. Patient survival duration was evaluated as primary outcome.

Results: After matching, biological v mechanical patients were well balanced. In the OVERALL group, 1,280 patients were assigned to mechanical v biological cohorts with 10-year mechanical v biological survival rate 42.3% v 37.2%, (Hazard ratio (HR) [confidence interval (CI)]= 0.902 [0.825-0.987], P=0.025). In patients over 65 years (GROUP 1), 532 pairs were matched with no significant survival difference between biological v mechanical valves (P=0.120). However, in GROUP 2 patients over 65 years who survived more than 5 years after surgery, those with a mechanical valve showed a significantly higher survival rate (HR[CI]= 0.780[0.6239–0.9770]. P=0.030). The time-varying Cox model indicated that mechanical valves provided significant survival benefit when the survival duration exceeded 8.1 years (Figure). In OVERALL matched patients, the cumulative incidence of MV reoperation at 10 years was 5.1% for mechanical versus 16.7% for biological valves (P < 0.001). Although the difference in MV reoperation rates disappeared for GROUP 1 patients over 65 years of age (P=0.340), a significant difference was observed if patients survived more than 5 years (GROUP 2) (P=0.010).

Conclusion: Mechanical valves provided better overall patient survival than biological valves after MVR. Contrary to guidelines, mechanical MVR showed significant survival benefit in patients over 65 with greater life expectancy. Valve selection should be individualized considering life expectancy, with 8.1 years as a useful reference value in patients over age 65.

Identify the source of the funding for this research project: No funding