More than one-third of patients with atrial fibrillation (AF) and a moderate-to-high stroke risk are treated with aspirin therapy without oral anticoagulation (OAC) therapy, according to research published in the Journal of the American College of Cardiology.

Jonathan C. Hsu, MD, MAS, Division of Cardiology, Department of Medicine, University of California, San Diego, and colleagues examined patients with AF from 2 outpatient cohorts who had intermediate-to-high thromboembolic risk (CHADS2 score ≥2 and CHADS2-VASc ≥2) and had been enrolled in the American College of Cardiology PINNACLE (Practice Innovation and Clinical Excellence) registry between 2008 and 2012. The researchers analyzed patient and practice-level factors involved in the prescription of either aspirin or oral anticoagulants (OAC) therapy.

The investigators identified 210,380 patients with a CHADS2 score ≥2 on antithrombotic therapy. Of those patients, 38.2% were treated with aspirin alone; 61.8% were treated with warfarin or a non-vitamin K antagonist OAC. In the patient cohort of CHADS2-VASc ≥2, 118,398 (40.2%) were treated with aspirin alone, and 176,244 (59.8%) were treated with warfarin or non-vitamin K antagonist OAC.

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After performing a multivariable adjustment, the researchers found that treatment with a prescription of aspirin alone was associated with hypertension, dyslipidemia, coronary artery disease, prior myocardial infarction, stable and unstable angina, recent coronary artery bypass graft, and peripheral artery disease. Conversely, male sex, higher BMI, prior stroke or transient ischemic attack, prior systemic embolism, and congestive heart failure were associated with prescriptions of OACs.

“In a large, real-world cardiac outpatient population of AF patients … more than 1 in 3 were treated with aspirin alone without OAC,” concluded Dr Hsu. “Specific patient characteristics predicted the prescription of aspirin therapy over OAC.”


  1. Hsu JC, Maddox TM, Kennedy K, et al. Aspirin instead of oral anticoagulant prescription in atrial fibrillation patients at risk for stroke. J Am Coll Cardiol. 2016;67(25):2913-2923; doi: 10.1016/j.jacc.2016.03.581