Preferability of Bioprostheses for Isolated Aortic Valve Replacement'a Comparative Study Between Mechanical and Bioprosthetic Valves'

Abstract

Comparative long-term performance characteristics of mechanical valves and bioprosthetic valves were analyzed retrospectively among patients who had undergore isolated aortic valve replacement between 1968 and 1987. One hundred sixty-seven patients received either mechanical (n = 82) or bioprosthetic (n = 85) valves. The cumulative follow-up was 926 patient-years (mean 6.1 ± 4.7 years, ranging from 0.5 to 20.2 years, 100% complete follow-up). Actuarial survival rate, including operative death, at 10 years was 74 ± 7% for mechanical and 77 ± 7% for bioprosthetic valve recipients. The rates of freedom from thromboembolism, structural valve failure, prosthetic valve endocarditis, and valve re-replacement at 10 years were 77 ± 7%, 100%, 96 ± 2% and 95 ± 3% for mechanical, and 94 ± 4%, 83 ± 8% (p<0.05), 88 ± 5% and 75 ± 8% (p<0.05) for bioprosthetic valve recipients, respectively. Thromboembolism occurred more frequently in the mechanical valve recipients (p<0.01), and structural valve failure in the bioprostheses recipients (p < 0.05). There was no mortality at the time of valve re-replacement. Most of the bioprosthesis recipients received no anticoagulation therapy beyond 3 months postoperatively. Cardiac medication in the late postoperative period was not required in 31.3% of bioprosthetic, and 3.2% of mechanical valve recipients (p<0.01). These results show that bioprosthesis in the aortic position exhibits a superb antithrombogenicity and may enable a drug-free state, though its limited durability requires reoperation. © 1990, The Japanese Circulation Society. All rights reserved.