Aspirin Instead of Blood Thinners Often Prescribed for Patients With Atrial Fibrillation

More than one-third of patients with atrial fibrillation who are have a moderate to high risk for stroke are being treated with aspirin, even though it is well known that blood thinners provide more protection.

More than one-third of patients with atrial fibrillation (AF) who are have a moderate to high risk for stroke are being treated with aspirin, even though it is well known that blood thinners are more effective, according to a new study published online in Journal of the American College of Cardiology. The study found that approximately 40% of more than 200,000 patients with AF who were being treated by cardiovascular specialists were receiving aspirin alone.

The study’s authors, led by Jonathan C. Hsu, MD, MAS, of the University of California San Diego School of Medicine, noted that the incidence of stroke is up to seven times greater among AF patients than in those without the condition because AF causes abnormal contractions in the heart’s upper chambers that make formation of blood clots more likely.

“Giving aspirin alone to this population may not be the best treatment because it is either minimally effective or not effective at all and still comes with risks, such as intracranial hemorrhage,” Hsu said in a statement. “Our study results show a gap in the appropriate treatment of AF patients at risk for stroke.”

The findings also reveal a critical need for cardiology specialists to adhere to the standardized recommendations regarding the use of oral anticoagulants instead of aspirin.

The study followed 2 groups of AF outpatients who had at intermediate to high risk of stroke and who were enrolled in the American College of Cardiology PINNACLE registry between 2008 and 2012. The authors used statistical analyses and models, adjusting for patient and real-world cardiology practice characteristics, to examine the predictors and prevalence of receiving aspirin alone versus oral anticoagulation prescriptions in AF patients at risk for stroke. They found that conditions related to coronary artery disease including hypertension, high cholesterol, and prior heart attack were associated with more frequent prescription of aspirin only. Male sex, a higher body mass index, a prior stroke, and congestive heart failure were associated with more frequent prescription of oral anticoagulants.

The researchers expressed concern about the high rate of aspirin-only prescriptions for AF patients with coronary artery disease uncovered in their study.

“It appears patients with more risk factors for having a stroke with AF are less likely to get the proper treatment, which is oral blood thinners,” said Hsu.

Approximately one-third of the AF patients who didn’t have significant coronary artery disease were prescribed both an oral anticoagulant and aspirin, putting them at higher risk for bleeding without any evidence that it would benefit them, the investigators said.

The biggest reason for underuse of appropriate oral anticoagulation therapy in AF patients may be physicians’ concern about bleeding, the authors surmise. More studies evaluating cardiovascular outcomes in AF patients prescribed aspirin only versus oral blood thinners, or a combination of the 2, are needed.