Aspirin Often Wrongly Prescribed for Atrial Fibrillation. nlm.nih.gov. 20/06/16. Blood thinners — not aspirin — dramatically cut the risk of stroke, researchers say. More than one-third of U.S. patients with the abnormal heartbeat atrial fibrillation who need a blood thinner to prevent strokes aren’t getting one, researchers say. About 40 percent of "a-fib" patients deemed at moderate to severe risk of stroke because of age or other conditions are prescribed aspirin alone rather than recommended blood thinners such as Xarelto (rivaroxaban) or warfarin, according to a new study.

"Despite clear guideline recommendations that patients at risk for stroke that have atrial fibrillation should be given blood thinners, many of these patients are not prescribed these potentially lifesaving medications," said lead researcher Dr. Jonathan Hsu. He is an assistant professor of medicine, cardiology and cardiac electrophysiology at the University of California, San Diego.
Another heart specialist agreed. "Aspirin is not an anticoagulant and is not effective in preventing strokes in patients with atrial fibrillation," said Dr. Samuel Wann, a cardiologist at Columbia St. Mary’s Hospital in Milwaukee. Wann is co-author of an editorial published with the study.
Also, even though women are at higher risk for stroke, men are more likely to get recommended blood thinners, the researchers noted.
In atrial fibrillation, the upper chambers of the heart beat rapidly and not in sync. The consequence of this irregular heartbeat is that blood clots can form and travel to the brain, causing a stroke. Blood thinners are used to help prevent clots.
This study — based on patients from 123 cardiology practices in the United States — highlights inappropriate prescribing practices, Hsu said. Aspirin helps prevent the molecules in blood called platelets from sticking together to form clots, but it’s not a blood thinner, he explained.
Hsu suggested that some doctors may be unaware of current guidelines. Also, he said some patients may not want to take blood thinners — perhaps because of the risk for bleeding — or are unaware of their higher odds for stroke.
Warfarin (Coumadin) was introduced about 60 years ago. Besides Xarelto, newer drugs include dabigatran (Pradaxa), apixaban (Eliquis) and edoxaban (Savaysa). But some patients find the newer drugs too expensive and the need for monthly doctor visits for blood tests while on warfarin too cumbersome, Hsu said.
"Nobody ever thanks me for putting them on a blood thinner, but we know this prevents strokes," Hsu added.
According to the latest guidelines, patients with atrial fibrillation who are 65 or older and those with at least one other condition — such as congestive heart failure, high blood pressure, diabetes or a prior stroke — should take a blood thinner. These factors are used by doctors to help assess stroke risk, Hsu said.
For the study, Hsu’s team used an American College of Cardiology registry to review medical records of more than 210,000 at-risk atrial fibrillation patients. They also conducted a secondary analysis of nearly 300,000 patients considered at-risk based on an updated guideline.
In both of these high-risk groups, roughly 40 percent were treated with aspirin and about 60 percent were prescribed a blood thinner, the investigators found.
Patients prescribed aspirin alone were more likely to be younger, thinner and female. They were also more likely to have another medical condition, such as diabetes, high blood pressure, high cholesterol, heart disease or a history of heart attack or heart bypass surgery, the findings showed.
Those prescribed blood thinners were more likely to be male, heavy, to have had a prior stroke or blood clot or congestive heart failure.
The study was published online June 20 in the Journal of the American College of Cardiology.
SOURCES: Jonathan Hsu, M.D., assistant clinical professor, medicine, cardiology and cardiac electrophysiology, University of California, San Diego; Samuel Wann, M.D., cardiologist, Columbia St. Mary’s Hospital, Milwaukee, Wis.; June 20, 2016, Journal of the American College of Cardiology, online
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