Impact of Effective Orifice Area on Long-Term Survival in Bioprosthetic versus Mechanical Aortic Valves.

Abstract

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

Methods: We analyzed 3265 patients ≤75 years of age 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.

Results: The mechanical AVR group was younger (60 vs 69 years, P < 0.001). For mechanical and bioprosthetic AVR groups, respectively, the median EOA was (2.0 [1.6, 2.4] vs 2.1 [1.7, 2.6], P < 0.001) cm² and EOA index was (1.0 [0.8, 1.2] vs 1.1 [0.9, 1.3], P < 0.001) cm²/m². In patients with EOA >2 cm², long-term adjusted risk of mortality was higher in the bioprosthesis group compared to the mechanical group (HR:1.33, P=0.010). However, no significant difference was observed for those with EOA <2 cm² (HR:1.01, P=0.932). Similarly, for EOA index of >1.08 cm²/m², bioprosthesis group was associated with higher risk of long-term mortality (HR=1.29, P=0.040), while no significant association was found for those with an EOA index <1.08 cm²/m² (HR=1.05, P=0.621).

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