[Problems of long-term therapy with anticoagulants].

Oral anticoagulants are highly effective for the prevention of recurrence of venous thromboembolism and of thromboembolic complications in rheumatic and non-rheumatic atrial fibrillation, dilated cardiomyopathy and in patients with prosthetic heart valves, but less effective for prevention of arterial thrombosis. Bleeding is the main side effect, the risk of fatal bleeding is 0.2 to 0.4% per year, depending on the intensity of treatment. The problem of the standardization of the prothrombin time determination has been solved by the introduction of the international normalized ratio. Recent studies have shown that a lesser degree of anticoagulation (INR 2.0 to 3.0) is sufficient to prevent venous thromboembolism and cardiac emboli. The measurement of activation markers of coagulation will probably allow a more rational monitoring in the near future.