Late results after mitral valve replacement with the Björk-Shiley and porcine prostheses

The late results of isolated mitral valve replacement were retrospectively evaluated in 357 patients receiving a Björk-Shiley (B-S) tilting disc prosthesis and 96 patients receiving a porcine bioprosthesis (PB) (Vascor or Carpentier-Edwards) between March, 1973, and July, 1978. The groups were comparable with regard to age, sex, New York Heart Association functional class, preoperative cardiac rhythm (sinus or atrial fibrillation), left atrial size (normal or enlarged), and presence of thrombus in the left atrium at operation. All of the B-S and 14 of the PB patients received long-term anticoagulant therapy. The median duration of follow-up was 46 months in the B-S group and 32 months in the PB group. At 5 years, survival was 70% for the B-S and 68% for the PB groups (NS). The percentage of patients free of thromboembolic episodes was 77% for the B-S and 78% for the PB groups (NS). Fifty-six percent of the B-S and 49% of the PB patients were alive and free of thromboembolism, complications related to anticoagulant therapy, or other valve-related complications (dehiscence, degeneration, or endocarditis) (NS). The presence of atrial fibrillation, enlarged left atrium, preoperative thromboembolic episodes, and left atrial thrombus had no effect on the incidence of thromboembolic complications with either prosthesis. From this analysis, it appears that the major advantage of the PB over the B-S prosthesis is its use in patients in whom long-term anticoagulation is contraindicated.