Optimal oral anticoagulation for patients with nonrheumatic atrial fibrillation and recent cerebral ischemia

To the Editor: The European Atrial Fibrillation Trial demonstrated the efficacy of anticoagulant therapy in preventing stroke in high-risk patients with atrial fibrillation.¹ The results were convincing because the number of events among untreated patients was large and the number of events among those treated with anticoagulants was small. Further analysis of the small group of events occurring among patients in the trial who were treated with anticoagulants can provide only a preliminary step toward the critical goal of specifying precisely the optimal range of anticoagulation for atrial fibrillation. Strong evidence that low intensities of anticoagulation are effective has facilitated.