Twelve-Year Comparison of a Bjork–Shiley Mechanical Heart Valve with Porcine Bioprostheses

Abstract

Background. patients undergoing heartvalve replacement may receive a mechanical prosthesis, necessitating lifelong anticoagulant treatment, or a porcine bioprosthesis, which involves no absolute need for anticoagulants. Methods. We carried out a randomized, prospective trial to compare the durability of the Bjork—Shiley mechanical prosthesis (spherical tilting-disk model) and the incidence of valve-related complications with those variables in the Hancock and the Carpentier-Edwards porcine prostheses. The mitral valve was replaced in 261 patients, the aortic valve in 211, and both in 61; the survivors have been followed up for a mean of 12 years. Results. We found a trend toward improved actuarial survival after 12 years with the Bjork—Shiley prosthesis, but this trend was not statistically significant (group with Bjork—Shiley valve vs. group with porcine valve [mean ±SE], 51.5±3.2 vs. 44.4±3.2 percent; P = 0.08). There was no significant difference in the actuarial incidence of reoperation after 5 years, but after 12 years significantly more patients with a porcine prosthesis had undergone reoperation (8.5±2.0 vs. 37.1 ±4.1 percent, P < 0.001). An analysis combining death and reoperation as end points for an actuarial assessment of survival with the original prosthesis intact confirmed that the patients with Bjork—Shiley prostheses had improved survival (48.6±3.2 vs. 30.0±3.0 percent after 12 years, P < 0.001). Bleeding requiring hospitalizaron or blood transfusion was significantly more frequent in the patients with Bjork—Shiley prostheses (18.6±3.2 vs. 7.1 ±2.3 percent after 12 years, P < 0.01). There was no significant difference after 12 years in the actuarial occurrence of embolism (Bjork—Shiley vs. porcine, 21.1 ±3.1 vs. 26.4±3.5 percent) or endocarditis (3.7±1.4 vs. 4.6±1.6 percent). Conclusion. Survival with an intact valve is better among patients with the Bjork—Shiley spherical tilting-disk prosthesis than among patients with porcine bioprostheses, but use of the Bjork—Shiley valve carries an attendant increased risk of bleeding associated with the need for anticoagulant treatment. (N Engl J Med 1991; 324:573–9). © 1991, Massachusetts Medical Society. All rights reserved.