Copenhagen Atrial Fibrillation, Aspirin and Anticoagulation (1989)


Prevention of VTE in chronic non-rheumatic AF

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To compare the efficacy of ASA and warfarin in preventing thromboembolic complications in chronic AF

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Trial design

Randomized, open (warfarin), double-blind (ASA) placebo-controlled phase III study
Active treatment: ASA 75 mg once daily (n=336)
Control treatment: warfarin standard dose (target INR 2.8–4.2) (n=335), placebo (n=336)

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Primary endpoint: thromboembolic complication (stroke, transient cerebral ischemic attack, or embolic complications to the viscera and extremities)
Secondary endpoint: death

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Trial participants

1007 patients aged ≥18 years (mean age 74.2 years), with ECG-verified chronic non-rheumatic AF

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Efficacy outcome: The incidence of thromboembolic complications (stroke, TIA, or embolic complications) on treatment was significantly lower in the warfarin group (5 of 335 patients, 2.0%/year) than in the ASA group (20 of 336 patients; 5.5%/year) or the placebo group (21 of 336 patients, 5.5%/year; relative risk reduction for warfarin vs. placebo 71%). There were 3 vascular deaths in the warfarin group (0.9%), 12 in the ASA group (3.6%), and 15 in the placebo group (4.5%). The trial was terminated early when interim analysis demonstrated a significant benefit from warfarin therapy
Safety outcome: Bleeding complications were more common in the warfarin group (21/335 patients) than in the ASA (2/336 patients) or placebo group (0)

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Efficacy: The incidence of thromboembolic complications and vascular mortality was significantly lower in the warfarin group than in the ASA and placebo groups, which did not differ significantly
Safety: There were more bleeding episodes with warfarin than with ASA

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Petersen P, Boysen G, Godtfredsen J, Andersen ED, Andersen B. Placebo-controlled, randomised trial of warfarin and aspirin for prevention of thromboembolic complications in chronic atrial fibrillation. The Copenhagen AFASAK study. Lancet 1989;1:175-179

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Corresponding author

Palle Petersen, MD, Department of Neurology, University Hospital, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark, e-mail:

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