Results of randomized mitral valve replacement with mechanical prostheses after 15 years

Between 1974 and 1976 150 consecutive patients (pts) were operated on for isolated mitral valve replacement (MVR). Björk-Shiley (BS), Lillehei-Kaste (LK), and Starr-Edwards (SE) (type 6210) prostheses were implanted at random. All survivors were prospectively followed by regular clinical examinations every 6 to 12 months for 15 years. The mean follow-up time was 14.8 years. A constant subjective improvement after 15 years was reported in 62% of pts with BS, 30% with LK, and 49% with SE. The cumulative 14-year survival rate was 0.62 +/- 0.13 (BS), 0.56 +/- 0.16 (SE), and 0.54 +/- 0.15 (LK), respectively. Late mortality was due to thromboembolic events (n = 3), bleeding complications (n = 3), congestive heart failure (n = 7), documented arrhythmias or sudden death (n = 6). Thrombotic valve thrombosis (1 BS, 1 LK, 2 SE) required reoperations. Linearized cumulative rates after 14 years for thromboembolic complications were 14.2 +/- 3.1 (BS), 15.8 +/- 3.7 (SE), 24.3 +/- 4.2 (LK). The cumulative risk of severe bleeding complications was not different: BS: 35.8, LK: 35.2, SE: 34.3. During the first years of observation no significant differences between these mechanical prostheses could be observed, however, after 14 years of long-term follow-up the cumulative event-free rates were more favorable for the BS prosthesis.