Get Adobe Flash player

More than 1 in 3 patients with atrial fibrillation and intermediate to high risk of stroke are prescribed aspirin instead of oral anticoagulants, contrary to guidelines, a recent study found.

Researchers examined data from the American College of Cardiology's PINNACLE Registry on 210,380 patients with a CHADS2 score greater than or equal to 2 between January 2008 and December 2012 and, in a secondary analysis, data on 294,642 patients with a comparable CHA2DS2-VASc score during the same timeframe. The goal was to examine the prevalence and predictors of treatment with aspirin only versus oral anticoagulation in patients with atrial fibrillation who were at risk for stroke and who were being treated by cardiovascular subspecialists. Results were published by the Journal of the American College of Cardiology on June 20.

A total of 210,830 patients were included in the CHADS2 group, and 294,642 patients were in the CHA2DS2-VASc group. Among the CHADS2 group, 38.2% were treated with aspirin alone and 61.8% were treated with oral anticoagulants. Among the CHA2DS2-VASc group, 40.2% were treated with aspirin and 59.8% were treated with oral anticoagulants. For both groups, patients who were prescribed aspirin were younger, had a lower body mass index, were more likely to be female, and were more likely to have another medical condition, including diabetes, hypertension, high cholesterol, coronary artery disease, prior heart attack, prior coronary artery bypass graft surgery, or peripheral artery disease.

After multivariable adjustment, hypertension, dyslipidemia, coronary artery disease, prior myocardial infarction, unstable and stable angina, recent coronary artery bypass grafting, and peripheral arterial disease were associated with prescription of aspirin alone. Meanwhile, male sex, higher body mass index, previous stroke or transient ischemic attack, previous systemic embolism, and congestive heart failure were associated with more frequent prescription of oral anticoagulation.

The authors noted that cardiologists may be prescribing aspirin instead of oral anticoagulants because they think that aspirin is as efficacious as oral anticoagulants. "Because many of the predictors of aspirin use alone include conditions that may warrant aspirin therapy regardless of the presence of [atrial fibrillation], much of the underutilization of appropriate anticoagulant agents may be driven by either the perception that aspirin by itself is sufficient or that the risk of aspirin plus anticoagulation is not worth the benefit," the authors wrote.

An editorial noted that clinicians may not realize that aspirin puts patients at risk for bleeding while providing no protection from stroke and that new and definitive evidence demonstrates that anticoagulation, not aspirin, is the treatment of choice to prevent strokes related to atrial fibrillation. The authors acknowledged that "The process of anticoagulation is not a particularly attractive proposition, entailing compliance with a long-term regimen that many patients and their physicians find burdensome, with inevitable nuisance, expense, annoying minor side effects, and infrequent, but devastating, complications, such as intracerebral hemorrhage, and with only an abstract future benefit for perhaps 4 or 5 of 100 patients who would suffer a stroke if they did not receive anticoagulation."

Still, the editorial stated, "Physicians and their patients should not sidestep the real risks of thromboembolism due to atrial fibrillation and the benefits of real anticoagulation, relying instead on aspirin, which has bleeding risk, but little, if any, therapeutic benefit. 'Take 2 aspirin and call me in the morning' is not appropriate treatment for a patient with atrial fibrillation at risk for thromboembolism."