Prevalence of atrial fibrillation and antithrombotic prophylaxis in emergency department patients

Background and Purpose-The emergency department (ED), as the point of first medical contact for many complaints referable to atrial fibrillation (AF) and a common source of primary care, occupies a unique position to identify AF patients at risk of stroke. This study evaluates that potential by determining the prevalence of AF in an ED population and assessing antithrombotic use in those patients with recurrent AF. Methods-This was a multicenter, retrospective, cross-sectional study of consecutive records of ED patients with AF identified by ECG between January and June 1998. American Heart Association and modified Stroke Prevention in Atrial Fibrillation criteria established high-risk patients and contraindications to anticoagulation, respectively. Results-We identified 866 records with ECG-proven AF in 78 787 patient visits for an estimated prevalence of 1.10% (95% CI, 1.03 to 1.17). We found that 556 records had a prior history of AF; of these, 221 (40%) used warfarin alone, 155 (28%) had antiplatelet therapy alone, 28 (5%) used both, and 152 (27%) had no antithrombotic therapy identified. Sixty-eight patients (12%; 95% CI, 0.10 to 0.15) were warfarin eligible and without antithrombotic therapy. An additional 64 (12%; 95% CI, 0.09 to 0.14) had antiplatelet therapy alone. In warfarin-eligible patients, no differences were identified between the anticoagulated and nonanticoagulated groups on the basis of age, sex, or race. Of patients on warfarin with a measured international normalized ratio, 61% (95% CI, 0.55 to 0.67) were outside the AHA-recommended range of 2.0 to 3.0. Conclusions-AF is a common finding in an ED population. Many are warfarin eligible and untreated or under-treated. Methods to increase anticoagulant use in this at-risk population warrant further investigation.