• Ratika Parkash, Vinnie Wee, Martin J Gardner, Jafna L Cox, Kara Thompson, Brenda Brownell, and David R Anderson.
• Department of Medicine, Dalhousie University and Capital Health, Halifax, Canada. ratika.parkash@cdha.nshealth.ca
• Can J Cardiol. 2007 May 1; 23 (6): 457-61.

BackgroundAtrial fibrillation (AF) is the most common adult arrhythmia, and significantly increases the risk of ischemic stroke. Oral anticoagulation may be underused and may be less effective in community settings than clinical trial settings.ObjectivesTo determine the rates of thromboembolism and bleeding in an ambulatory cohort of patients with AF.MethodsObservational study of Nova Scotian residents with AF identified by electrocardiogram in ambulatory settings between November 1999 and January 2001. Main outcome measures were rates of thromboembolism and bleeding over two years.ResultsFour hundred twenty-five patients were included in the study. The mean (+/-SD) age was 70.6+/-11.1 years, and 40% were women. Warfarin therapy was used by 68% of patients. Sixty-two per cent of patients had hypertension, 21% had a previous stroke or transient ischemic attack, 44% had congestive heart failure and 20% were diabetic. The overall rate of thromboembolic events was 2.7% in warfarin users and 8.5% in nonwarfarin users over two years, with an RR reduction of 68% (OR 0.31, 95% CI 0.09 to 0.91; P=0.047). The annual rate of ischemic stroke was 1.2% and 3.1% in warfarin and nonwarfarin users, respectively, with an RR reduction of 62% (OR 0.29, 95% CI 0.08 to 1.04; P=0.057). The overall rate of major bleeding was 2.6% in warfarin users and 1.4% in nonwarfarin users (P=0.667). The annual mortality rate was 7.79% in warfarin users and 9.93% in nonwarfarin users (P=0.192).ConclusionsWarfarin use was found to significantly reduce the rate of thromboembolic events without a concomitant increase in hemorrhagic events. The present study confirms the effectiveness of warfarin therapy in a population-based cohort.

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