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That risk increases about the same whether they are taking warfarin or a newer, more expensive drug, Xarelto (rivaroxaban).
Atrial fibrillation is an abnormal heart rhythm in which the upper chambers of the heart quiver or flutter instead of contracting correctly, raising the risk of stroke fivefold. Patients are often put on anti-clotting drugs to ward off stroke.
But some people need to temporarily stop taking anti-clotting drugs before surgery or other medical procedures to prevent excess bleeding, while other patients permanently stop taking anti-clotting drugs because of side effects, researchers said.
Researchers analyzed data from a previous trial including more than 14,000 patients with atrial fibrillation. In that trial, rivaroxaban was found to be as effective as warfarin in preventing stroke and blood clots. Both drugs carried about an equal risk of causing excessive bleeding.
In the new study, researchers concentrated on patients who had stopped taking the drugs, either temporarily or permanently. Regardless of which drug was stopped, the rate of strokes and blood clots went up about the same.
Decisions to halt either warfarin or rivaroxaban should be made carefully, since going off the drugs means the heightened stroke risk associated with atrial fibrillation returns, said lead researcher Dr. Manesh Patel, an assistant professor of medicine at Duke University School of Medicine.
"All anticoagulation decisions in patients with atrial fibrillation require risk benefit analysis, and for patients and physicians periods without anticoagulation coverage should be minimized," Patel said.
The study was to be presented Wednesday at the American Heart Association Emerging Science Series.
Atrial fibrillation affects more than 2.3 million men and women in the United States and accounts for more than 15 percent of all strokes, said Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles. Anticoagulation therapy reduces the risk of stroke by 60 to 80 percent in patients with atrial fibrillation, Fonarow said.
Yet there are key differences between the older and the new drug, including price and how much monitoring is needed, experts said.
Patients taking warfarin need to have the levels of the drug monitored and adjusted regularly to insure it is being effective and not increasing the risk of serious bleeding, while patients taking rivaroxaban don't require as careful monitoring.
"While the newer oral anticoagulants rivaroxaban and dabigatran (Pradaxa) cost approximately $250 a month compared with warfarin, which costs only a few dollars a month, these new agents have the advantage of not requiring monthly blood draws and providing more reliable anticoagulation," Fonarow said.
Because this research has not yet been published, it has not been subjected to the rigorous scrutiny given to research published in peer-reviewed medical journals and should be viewed as preliminary.
The study was partly funded by Johnson & Johnson and Bayer HealthCare AG, which makes rivaroxaban.
Copyright © 2012 HealthDay. All rights reserved.
SOURCES: Manesh Patel, M.D., assistant professor, medicine, Duke University School of Medicine, Durham, N.C.; Gregg Fonarow, M.D., professor, cardiology, University of California, Los Angeles; April 25, 2012, presentation, American Heart Association's Emerging Science Series