Oral anticoagulant therapy: Efficacy, safety and the low-dose controversy

The issue of optimal duration of oral anticoagulant therapy after a first e pisode of venous thromboembolism is still unresolved. However, recent data suggest that short (6 weeks to 3 months), intermediate (3-6 months) or inde finite-term anticoagulant therapy should be adopted on the basis of the cla ssification of patients into low-, intermediate- a nd high-recurrence-risk groups, respectively. Oral anticoagulants have been shown to effectively pr event cardioembolic stroke in nonvalvular atrial fibrillation. Recent data seem to suggest that their safety can be ameliorated with adequate risk str atification on the basis of clinical and echocardiographic features. After unstable angina and non-Q-wave myocardial infarction, oral anticoagulant th erapy (INR range 2-3) combined with aspirin has been shown to be advantageo us over aspirin alone, although at the cost of a slight increase in bleedin g. Bleeding complications are major drawbacks of oral anticoagulant therapy thus limiting their generalized adoption in recognized indications. To sha rply reduce the bleeding risk and need of laboratory control, the low- or f ixed-dose oral anticoagulant approach has been evaluated. In primary preven tion and in low or low-to-moderate thrombotic risk, minidose warfarin treat ment has been shown to be advantageous. In secondary prevention, and in pat ients at high risk for recurrent venous or arterial thrombotic events, stan dard range (INR 2-3) or higher level of anticoagulation is needed. Copyrigh t (C) 1999 S. Karger AG, Basel.