OPTIMAL ORAL ANTICOAGULANT-THERAPY IN PATIENTS WITH NONRHEUMATIC ATRIAL-FIBRILLATION AND RECENT CEREBRAL-ISCHEMIA

Background. A number of studies have demonstrated the efficacy of oral anticoagulant therapy in reducing the risk of stroke and systemic emb olism in patients with nonrheumatic atrial fibrillation, However, both the targeted and the actual levels of anticoagulation differed widely among the studies, and a number of studies failed to report standardi zed prothrombin-time ratios as international normalized ratios (INRs), We therefore performed an analysis to determine the intensity of oral anticoagulant therapy in nonrheumatic atrial fibrillation that provid es the best balance between the prevention of thromboembolism and the occurrence of bleeding complications. Methods. We calculated INR-speci fic incidence rates for both ischemic and major hemorrhagic events occ urring in 214 patients who received anticoagulant therapy in the Europ ean Atrial Fibrillation Trial, a secondary-prevention trial in patient s with nonrheumatic atrial fibrillation and a recent episode of minor cerebral ischemia. Results. The optimal intensity of anticoagulation w as found to lie between an INR of 2.0 and an INR of 3.9. No treatment effect was apparent with anticoagulation below an INR of 2.0, The rate of thromboembolic events was lowest at INRs from 2.0 to 3.9, and most major bleeding complications occurred with treatment at intensities w ith INRs of 5.0 or above. Conclusions. To achieve optimal levels of an ticoagulation with the lowest risk in patients with atrial fibrillatio n and a recent episode of cerebral ischemia, the target value for the INR should be set at 3.0, and values below 2.0 and above 5.0 should be avoided.