Some Atrial Fibrillation Patients Receive Unnecessary Blood Thinners

UCSF Researchers Believe Cardiology Specialists May Be Unaware of Risk

By Scott Maier

About a quarter of all atrial fibrillation (AF) patients at the lowest risk for stroke receive unnecessary blood thinners from cardiology specialists, according to UCSF researchers, and these providers must be made aware of the resulting potential health risks.

Their research letter appears online and will be in the June 1 issue of JAMA Internal Medicine.

“The irony is that there is a general push to get providers to prescribe these drugs, and they are also generally under-prescribed among many AF patients who actually need them,” said senior author Gregory Marcus, MD, MAS, director of clinical research in the UCSF Division of Cardiology. “Our study suggests people are trying to do the right thing but, due to a lack of understanding of some of the critical nuances, go too far in that direction in low-risk patients.”

In AF, electrical impulses are triggered from many areas in and around the upper chambers (atria) of the heart instead of just one area. This activity is chaotic, and the atrial walls quiver rather than contract normally in moving blood to the lower chambers (ventricles).

For atrial fibrillation patients at risk for thromboembolism, anticoagulation therapies with warfarin or other drugs reduce morbidity and mortality. But because their use carries a bleeding risk, they are not recommended for AF patients at a particularly low risk for stroke.

In fact, current guidelines do not recommend oral anticoagulation in patients under age 60 without heart disease or other known risk factors for thromboembolism or in AF patients without any established risk factor for stroke. The previous guidelines, which were in place at the time the data for this study were collected, had, in fact, a very strong recommendation specifically to avoid anticoagulants in that population.

Marcus and his colleagues examined the prevalence of non-guideline adhering oral anticoagulant prescription in young and healthy patients at the lowest risk for thromboembolism by reviewing nearly 11,000 patients nationwide age 60 and under from the overall Practice Innovation and Clinical Excellence (PINNACLE) Registry® of the National Cardiovascular Data Registry between 2008-2012. The PINNACLE Registry was created in 2008 by the American College of Cardiology as the first national, prospective, office-based cardiac quality improvement registry in the United States and enrolled more than 1.7 million patients.

Surprisingly, about 25 percent of patients (2,561) were prescribed oral anticoagulant therapy contrary to contemporary guideline recommendations. Further, the researchers found males with AF at the lowest risk of stroke were more likely to be prescribed oral anticoagulation than females, as were older patients and overweight patients without stroke risk factors.

As a result, providers may not be fully aware of the potential risks of these drugs or the particularly low risk of stroke in certain populations.

“Practitioners who prescribe blood thinners need to be diligent about weighing the risks and benefits of these medications,” said lead author Jonathan C. Hsu, MD, MAS, of the UC San Diego Division of Cardiology and recent UCSF cardiology and electrophysiology graduate. “In those patients with no risk factors for stroke, the risk of bleeding likely outweighs the benefit of stroke reduction. The fact that blood thinners were prescribed to so many patients with no risk factors for stroke is a wake up call that we need to do better for our patients.”

Other contributors to the JAMA Internal Medicine research letter were Paul S. Chan, MD, MSc, and Fengming Tang, MS, of the Saint Luke Mid America Heart Institute and the University of Missouri, Kansas City; and Thomas M. Maddox, MD, MSc, of the Veterans Affairs Eastern Colorado Health Care System/University of Colorado School of Medicine. Funding was provided by the National Heart Lung and Blood Institute and the U.S. Department of Veterans Affairs.

UCSF is the nation's leading university exclusively focused on health. Now celebrating the 150th anniversary of its founding as a medical college, UCSF is dedicated to transforming health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. It includes top-ranked graduate schools of dentistry, medicine, nursing and pharmacy; a graduate division with world-renowned programs in the biological sciences, a preeminent biomedical research enterprise and top-tier hospitals, UCSF Medical Center and UCSF Benioff Children's Hospitals.