Influence of effective orifice area on long-term survival in bioprosthetic versus mechanical aortic valves

We examined the potential influence of effective orifice area (EOA) and EOA index (EOAi) on survival between bioprosthetic and mechanical valves.

We analyzed 3265 patients aged 75 years or younger undergoing aortic valve replacement with or without coronary artery bypass grafting. EOA and EOAi were obtained from predischarge echocardiograms. Bootstrapped logistic regression and restricted cubic splines identified optimal survival cut points for EOA and EOAi. Multivariable Cox proportional hazards models were fitted, and adjusted Kaplan-Meier survival curves were generated using the identified EOA cut points.

The mechanical aortic valve replacement group was younger (age 60 vs 69 years; P < .001). For mechanical and bioprosthetic aortic valve replacement groups, respectively, the median EOA was (2.0 cm²; range, 1.6-2.4 vs 2.1 cm²; range, 1.7-2.6 cm²; P < .001) and EOA index was (1.0 cm²/m²; range, 0.8-1.2 cm²/m² vs 1.1 cm²/m², range, 0.9-1.3 cm²/m²; P < .001) In patients with EOA ≥2 cm², long-term adjusted risk of mortality was higher in the bioprosthesis group compared with the mechanical group (hazard ratio, 1.33; P = .010). However, no significant difference was observed for those with EOA <2 cm² (hazard ratio, 1.01; 95% CI, 0.83-1.23; P = .932). Similarly, for EOA index ≥1.08 cm²/m², the bioprosthesis group was associated with higher risk of long-term mortality (hazard ratio, 1.29; 95% CI, 1.01-1.64, P = .040), whereas no significant association was found for those with an EOA index <1.08 cm²/m² (hazard ratio, 1.05; P = .621).

In this cohort, there was a survival advantage of mechanical valves over bioprostheses in larger valve sizes but not in patients with smaller EOA metrics.