Anticoagulants versus antiplatelet therapy for preventing stroke in patients with nonrheumatic atrial fibrillation and a history of stroke or transient ischemic attacks.

BACKGROUND: People with nonrheumatic atrial fibrillation who have had a transient ischemic attack or minor ischemic stroke are at risk of recurrent stroke. OBJECTIVES: The objective of this review was to compare the effect of anticoagulants with antiplatelet therapy, for secondary prevention, in people with nonrheumatic atrial fibrillation and previous cerebral ischaemia. SEARCH STRATEGY: The reviewer searched the Cochrane Stroke Group trials register and contacted trialists. SELECTION CRITERIA: Randomised trials comparing oral anticoagulants with aspirin in patients with non-rheumatic atrial fibrillation and a previous transient ischaemic attack or minor ischaemic stroke. DATA COLLECTION AND ANALYSIS: One reviewer extracted the data. MAIN RESULTS: One trial was included, involving 455 patients. They received either anticoagulants (International Normalised Ratio 2.5 to 4.0), or 300 milligrams of aspirin per day. People joined the trial within three months of transient ischaemic attack or minor stroke. The mean follow-up was 2.3 years. Anticoagulant therapy approximately halved the odds of serious vascular events (odds ratio 0.55, 95% confidence interval 0.36 to 0. 83). This equates to preventing an extra 50 vascular events per year for every 1000 patients treated. Anticoagulant therapy decreased the odds of recurrent stroke by two-thirds (odds ratio 0.35, 95% confidence interval 0.22 to 0.59). This translates to preventing an extra 60 strokes for every 1000 patients treated per year. Major extracranial bleeds occurred more often in patients given anticoagulants (odds ratio 4.65, 95% confidence interval 1.66 to 12.99). The absolute difference was 2.8% versus 0.9% bleeds per year. None of the patients on anticoagulants and one on aspirin had an intracerebral bleed. REVIEWER'S CONCLUSIONS: The evidence from one trial suggests that anticoagulant therapy can benefit people with nonrheumatic atrial fibrillation and recent cerebral ischaemia. Aspirin may be a useful alternative if there is a contraindication to anticoagulant therapy. The risk of adverse events appears to be higher with anticoagulant therapy than aspirin.