Aspirin Use in Anticoagulation-Eligible AF Patients
What are the patient and practice-level factors associated with use of aspirin alone as compared to oral anticoagulation (OAC) in patients with atrial fibrillation (AF) at intermediate or high risk of stroke?
The authors investigated the American College of Cardiology PINNACLE (Practice Innovation and Clinical Excellence) Registry between 2008 and 2012. Using hierarchical modified Poisson regression models, the authors examined the prevalence and predictors of aspirin only therapy versus OAC therapy in AF patients at intermediate or high risk of stroke, as estimated by the CHADS2 and CHA2DS2-VASc scores.
Of the 294,642 patients with a CHA2DS2-VASc score ≥2 on any antithrombotic therapy, 118,398 (40.2%) were treated with aspirin alone and 176,244 (59.8%) were treated with warfarin or a direct oral anticoagulant. Hypertension, dyslipidemia, coronary artery disease, prior myocardial infarction, unstable and stable angina, recent coronary artery bypassin grafting, and peripheral arterial disease were predictors of aspirin only therapy. Male gender, higher body mass index, prior stroke/transient ischemic attack, prior systemic embolism, and congestive heart failure were associated with more frequent use of OAC therapy.
The authors concluded that more than one in three patients at intermediate or high risk of stroke were treated with aspirin therapy only.
Although somewhat dated, this study highlights significant underuse of OAC therapy in AF patients at intermediate and high risk of therapy. Interestingly, the majority of patient characteristics predicting aspirin only therapy are those where patients would commonly necessitate antiplatelet therapy (e.g., coronary arterial disease and peripheral arterial disease). Recent studies have highlighted the potential role for OAC + clopidogrel therapy (without aspirin) in patients with acute coronary syndromes or recent percutaneous coronary intervention as a strategy to improve stroke prevention while minimizing bleeding complications. More contemporaneous data will be needed to assess the impact of these studies.
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