Thromboembolic complications of heart valve prostheses

One hundred seventy patients with prosthetic heart valves receiving anticoagulant therapy have been followed at one to four week intervals for three to sixty-eight months (mean: 26 months). The overall incidence of late emboli was 16 per cent. The risk was approximately the same for patients carrying aortic, mitral, and multiple prostheses. Consistently good control of prothrombin time (0 to 15 per cent of recorded values outside the therapeutic range) is effective in reducing the incidence of thromboembolism, which was 3 per cent in these patients. Atrial fibrillation has not been an additional risk factor. The incidence of embolic episodes has a tendency to decrease in the third and fourth year postoperatively and no emboli were recorded during the fifth and sixth year follow-up. Completely cloth-covered prostheses appear to bear a low risk of thromboembolic complications (4 per cent in the present series).