Comparative evaluation of mechanical and biological prostheses in patients with aortic stenosis

OBJECTIVES: The commonly accepted aortic valve prostheses have been either mechanical or biological. Each type has its advantages and disadvantages, with age being the most widely accepted variable to determine the best option. There is, however, a range between 60 and 70 years where an individualized approach is required. METHODS: This is a retrospective study. The primary outcome was overall survival based on the type of prosthesis used, stratified by effect modifiers. Association between prosthesis type and mortality rate was evaluated using the incidence rate ratio. Secondary outcomes included cardiovascular survival, postoperative mortality and complications, adjusted for age. Cox regression analysis was performed to account for confounders. Variation in the hazard ratio for death by age was explored by fitting a restricted cubic spline to the interaction between age and valve type. We included all adult patients who underwent surgical aortic valve replacement for severe stenosis in Uruguay from 2011 to 2021. A total of 3944 patients were enrolled; 1708 were females. Median follow-up time was 4.5 years. RESULTS: Bioprostheses (BP) were associated with higher mortality in males and in patients without statins. When mortality rate was stratified by age, BP were associated with a higher risk in patients younger than 60 and a lower risk in the 70-79 age group. CONCLUSIONS: BP are associated with worse survival in male patients and in the <60-year-old age group. Gender and statins should be considered when deciding the prosthesis for patients in the 60-69 age group. When the relative survival benefit of BP was analysed, 70 years was identified as the threshold at which their benefit became evident compared to mechanical prostheses.