Oral anticoagulation for cerebral ischemia of arterial origin: high initial bleeding risk.

BACKGROUND: The use of oral anticoagulant therapy for the prevention of arterial thromboembolism in patients who have had ischemic stroke is controversial. Coumarins may increase the bleeding risk in patients with cerebral ischemia of arterial origin.
OBJECTIVES: 1) To calculate incidence rates of bleeding and thromboembolic events in patients with noncardiac cerebral ischemia who were treated routinely in an anticoagulation clinic. 2) To assess which factors contribute to the occurrence of events. 3) To determine the optimal intensity of oral anticoagulant therapy in these patients.
METHODS: The authors studied all patients treated for noncardiac cerebral ischemia at the Leiden anticoagulation clinic between 1993 and 1998. Outcome events were major hemorrhage, major arterial thromboembolism, and death.
RESULTS: The authors observed 356 patients for 644 patient-years. The incidence of major hemorrhage was 3.9 per 100 patient-years (95% CI, 2.5 to 5.7) and that of thromboembolism was 3.0 per 100 patient-years (95% CI, 1.8 to 4.6). The incidence of hemorrhage varied with the duration of treatment (relative risk [RR] of the first versus the second half-year, 3.8; 95% CI, 1.9 to 7.6), age (RR for age >65 years, 3.7; 95% CI, 1.1 to 12.3), and the intensity of oral anticoagulation (RR, 1.8 for each 0.5 international normalized ratio [INR] unit increase; 95% CI, 1.5 to 2.3). The optimal intensity of oral anticoagulant therapy was 2.5 to 3.5 INR; the best target value was 3.0 INR.
CONCLUSION: The risk of hemorrhage with anticoagulant therapy is high in patients with ischemic stroke of arterial origin but is mainly confined to early use and elderly patients.