Rates of thromboembolism with three different mechanical heart valve prostheses: randomised study.

In 434 operations for valvular heart disease, patients were randomised to receive Björk-Shiley, Edwards-Duromedics, or Medtronic-Hall mechanical prostheses. At a median follow-up time of 37.5 months there were no differences in hazard of death or non-embolic events. In the first six postoperative months the incidence of thromboembolism was about the same for the three valves. Subsequently, however, the incidence of thromboembolism for the Edwards-Duromedics valve was 3.9 times higher than for the Björk-Shiley valve, and for the Medtronic-Hall valve 2.6 times higher than for the Björk-Shiley valve.