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BACKGROUND AND PURPOSE: This study aims to provide observational data on the relationship between the timing of antithrombotic treatment and the competing risks of severe thrombotic and hemorrhagic events in a cohort of Swedish patients with atrial fibrillation and intracerebral hemorrhage (ICH).

METHODS: Patients with atrial fibrillation and a first-ever ICH were identified in the Swedish Stroke Register, Riksstroke, 2005 to 2012. Riksstroke was linked with other national registers to find information on treatment, comorbidity, and outcome. The optimal timing of treatment in patients with low and high thromboembolic risk was described through cumulative incidence functions separately for thrombotic and hemorrhagic events and for the combined end point vascular death or nonfatal stroke.

RESULTS: The study included 2619 ICH survivors with atrial fibrillation with 5759 person-years of follow-up. Anticoagulant treatment was associated with a reduced risk of vascular death and nonfatal stroke in high-risk patients with no significantly increased risk of severe hemorrhage. The benefit seemed to be greatest when treatment was started 7 to 8 weeks after ICH. For high-risk women, the total risk of vascular death or stroke recurrence within 3 years was 17.0% when anticoagulant treatment was initiated 8 weeks after ICH and 28.6% without any antithrombotic treatment (95% confidence interval for difference, 1.4%-21.8%). For high-risk men, the corresponding risks were 14.3% versus 23.6% (95% confidence interval for difference, 0.4%-18.2%).

CONCLUSIONS: This nationwide observational study suggests that anticoagulant treatment may be initiated 7 to 8 weeks after ICH in patients with atrial fibrillation to optimize the benefit from treatment and minimize risk.