Propensity-Matched Long-Term Analysis of Mechanical versus Stentless Bioprostheses for Aortic Valve Replacement in Younger Patients

Objectives: The choice of aortic valve prosthesis in younger patients is controversial. Although mechanical substitutes are recommended in younger patients due to lower reoperation rates, the use of bioprostheses increases, as anticoagulation is not required and degenerated xenografts can be treated by transcatheter aortic valve replacement. Stentless aortic valve replacement (SAVR) was introduced two decades ago, aiming at better durability than stented bio-prostheses due to superior hemodynamic properties. Yet no long-term comparison to mechanical prostheses in younger patients is available.

Methods: All adult patients, aged £60 years, who underwent aortic valve replacement between 1993 and 2002 were identified. After exclusion of patients with congenital heart disease, aortic dissections, and Ross procedures, 158 patients with SAVR (Group B) and 229 patients with mechanical prostheses (Group M) were obtained. Propensity matching (including 24 baseline characteristics) resulted in 66 patient-pairs. Mortality and morbidity, including stroke, bleeding, and reoperation, were analyzed.

Results: Group baseline characteristics and operative data did not differ significantly after propensity matching. Hospital mortality was 0% in group B and 1.5% in group M, respectively (p = 0.3). Total follow-up was 1,967.3 patient-years (completeness: 96.1%, mean: 14.9 ± 6.9 years). Events of bleeding (p = 0.49) and stroke (p = 0.40) were evenly distributed in both groups. At 15 years, survival was 60.0 ± 6.1% in group B and 64.1 ± 6.0% in group M (p = 0.56), freedom from reoperation was 48.5 ± 7.1% in group B and 87.8 ± 4.3% in group M (p = 0.00), respectively.

Conclusion: Even though reoperation rate was significantly higher after SAVR, long-term survival, stroke rate, and bleeding rate were comparable to mechanical prostheses. Thus, SAVR is an alternative to mechanical aortic prostheses in younger patients, who want or have to avoid oral anticoagulation.