More than one-in-three patients with atrial fibrillation (AFib), or irregular heartbeat, with an intermediate-to-high-risk of stroke are prescribed aspirin instead of oral anticoagulants, despite guidelines recommending the use of oral anticoagulants for this group of patients, according to a study published in the Journal of the American College of Cardiology.
Oral anticoagulants are one type of blood thinner used to prevent blood clots, which can lead to stroke. Warfarin or the newer oral anticoagulants are recommended for patients identified as at-risk for stroke using the CHADS2 model. This model uses age, defined as 75 or older; congestive heart failure; hypertension; diabetes, and prior stroke to assess a patient’s likelihood of having a stroke. A newer model, CHA2DS2-VASc, which incorporates additional variables – including an age range between 65 and 74, gender, and the presence of vascular risk factors – has been recommended in updated guidelines. It is considered a more sensitive tool for stroke risk assessment. For both models, patients with a score greater than or equal to 2 should be considered for anticoagulation therapy.
Using data from the American College of Cardiology’s PINNACLE Registry, researchers looked at records from 210,380 patients with a CHADS2 score greater than or equal to 2 between January 2008 and December 2012. In a secondary analysis, the researchers assessed records from 294,642 patients with a comparable CHA2DS2-VASc score during the same timeframe.
Results showed that among the CHADS2 group, 38 percent were treated with aspirin, and nearly 62 percent were treated with oral anticoagulants. Among the CHA2DS2-VASc group, 40 percent were treated with aspirin, while 60 percent were treated with oral anticoagulants.
For both groups, AFib 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. Those prescribed oral anticoagulants were more likely to be male, have a higher body mass index, a history of a prior stroke or blood clot, or a history of congestive heart failure.
Jonathan C. Hsu, M.D., M.A.S., the study’s lead author and assistant clinical professor of medicine, cardiology and cardiac electrophysiology at the University of California, San Diego, said cardiovascular specialists may be prescribing aspirin instead of oral anticoagulants because they have “the misperception that aspirin exhibits adequate efficacy compared to oral anticoagulants.” He also noted that men had a 6 percent greater likelihood of being prescribed anticoagulants despite the fact that women have an increased risk of stroke.
In an accompanying editorial, Sanjay Deshpande, M.D., medical director of electrophysiology at Columbia St. Mary’s Hospital, in Milwaukee, and L. Samuel Wann, M.D., a cardiologist at Columbia St. Mary’s Hospital, said that clinicians may not realize that aspirin puts patients at risk for bleeding with “virtually no protection from stroke.”
“It is concerning that the highly motivated, conscientious, and talented cardiologists working in quality-conscious institutions that contribute their data to the NCDR are not prescribing anti-coagulation in one-third of their qualifying patients, as defined by our guidelines,” the editorial authors wrote.
Deshpande and Wann said “new and definitive evidence” demonstrates that anticoagulation, not aspirin, is the treatment of choice to prevent strokes related to atrial fibrillation, but they acknowledged that anticoagulation is difficult, “entailing compliance with a long-term regimen that many patients and their physicians find burdensome.”