Improved durability of bioprostheses has led some surgeons to recommend biologic rather than mechanical prostheses for patients younger than 65 years. We compared late results of contemporary bioprostheses and bileaflet mechanical prostheses in patients who underwent aortic valve replacement between 50 and 70 years old. In this retrospective study, patients received either St Jude bileaflet valves or Carpentier-Edwards bioprostheses. Operations were performed between January 1991 and December 2000, and groups were matched one-to-one according to age, sex, need for coronary artery bypass grafting, and valve size. Four hundred forty patients were matched, and follow-up was 92% complete, with median durations of 9.1 years for patients who received mechanical valves and 6.2 years for patients who received bioprostheses. The 5- and 10-year unadjusted survivals were 87% and 68% for mechanical valves and 72% and 50% for bioprostheses, respectively (P < .01). Freedoms from reoperation at 10 years were 98% for mechanical valves and 91% for bioprostheses (P = .06). Rates of late stroke or other embolic events and of endocarditis were similar between groups. Hemorrhagic complications necessitating hospitalization occurred in 15% of patients with mechanical valves and 7% of patients with bioprostheses (P = .01). Notably, 19% of patients with bioprostheses were receiving warfarin sodium at last follow-up. After adjustment for unmatched variables, including diabetes, renal failure, lung disease, New York Heart Association functional class, ejection fraction, and stroke, the use of a mechanical valve was protective against late mortality (hazard ratio 0.46, P < .01). In this study, patients aged 50 to 70 years who underwent aortic valve replacement with mechanical valves had a survival advantage relative to matched patients who received bioprostheses. These findings question recommendations of bioprostheses for younger patients and suggest that a randomized trial may be warranted.
