Long-term outcomes of patients undergoing mechanical versus bioprosthetic aortic root replacement

We evaluated the impact of valve type (mechanical vs. bioprosthetic) on survival after aortic root replacement (ARR).

In a propensity-matched analysis, we evaluated consecutive operations from 2010 to 2018. Patients were identified using a prospectively maintained institutional database. Patients with infective endocarditis were excluded. Kaplan-Meier survival estimation and multivariable Cox regression analysis were performed. Cox regression adjusted for age, sex, baseline comorbidities, and operative variables. Propensity score matching yielded 153 pairs of patients.

A total of 893 patients were identified. We excluded 192 patients with endocarditis and evaluated 701 patients. Of these patients, 455 (64.9%) received a bioprosthetic valve, 246 (35.1%) received a mechanical valve. Median follow-up was 4.06 years. The proportion of aortic dissections and circulatory arrest as well as cardiopulmonary bypass and ischemic times were similar across groups (p = .207, p = .086, p = .668, p = .454, respectively). Operative mortality was significantly higher in the bioprosthetic valve group (7.9% vs. 2.4%, p = .004). Total length of hospital stay was longer (11.4 ± 11.0 vs. 9.5 ± 10.1, p < .001) and there was a higher proportion of prolonged postoperative ventilation >24 h (21.3% vs. 13.0%, p = .007) in the bioprosthetic group. Postoperative outcomes were similar, regarding stroke (p = .077), re-exploration for bleeding (p = .211), new dialysis requirement (p = .077), long-term bleeding complications (p = .561), and reoperations (p = .755). Mechanical valve replacement was associated with improved long-term survival (adjusted HR 0.42, 95% CI: 0.23-0.77, p = .005).

These findings suggest that mechanical valves for ARRs may confer a survival benefit over bioprosthetic valves. Surgeon bias was likely to account for this survival advantage.