SPECIAL ARTICLE Assessment of Three Schemes for Stratifying Stroke Risk in Patients with Nonvalvular

PURPOSE: The risk of ischemic stroke varies widely among patients with nonvalvular atrial fibrillation, influencing the choice of prophylactic antithrombotic therapy. We assessed three schemes for stroke risk stratification in these patients who were treated with aspirin and who did not have prior cerebral ischemia. SUBJECTS AND METHODS: Criteria from three schemes of risk stratification were applied to a longitudinally observed co-hort of patients with atrial fibrillation who did not have prior cerebral ischemia and who were treated with aspirin alone or aspirin combined with low, ineffective doses of warfarin in a multicenter clinical trial. The ability of the schemes to identify patients at high ($6%), low (#2%), and intermediate annual risks of ischemic stroke was assessed. RESULTS: During a mean follow-up of 1.8 years, 48 ischemi