Nearly 40 percent of
patients treated with aspirin alone despite previous data showing blood
thinners more beneficial
Newswise, June 22, 2016 — Researchers at University of
California San Diego School of Medicine and University of California, San
Francisco School of Medicine report that more than 1 in 3 atrial fibrillation
(AF) patients at intermediate to high risk for stroke are treated with aspirin
alone, despite previous data showing this therapy to be inferior to blood
thinners.
The findings publish online June 20 in theJournal of the
American College of Cardiology.
The study, which examined more than 200,000 AF patients at
risk for stroke, found approximately 40 percent were treated with aspirin alone
even though previous studies have demonstrated this treatment option is not as
beneficial as oral blood thinners, such as warfarin, for reduction of
thromboembolism, an obstruction of a blood vessel by a clot that has become
dislodged.
The incidence of stroke for AF patients is up to seven times
greater than in those without the condition. In AF, electrical impulses in the
upper chambers of the heart are chaotic and the atrial walls quiver rather than
contract normally in moving blood to the lower chambers. As a result, blood
clots may form.
“Stroke prevention is critical to the management of AF
patients. However, giving aspirin alone to this population may not be the best
treatment therapy because it is either minimally effective or not effective at
all and still comes with risks, such as intracranial hemorrhage,” said lead
author Jonathan C. Hsu, MD, cardiologist at UC San Diego Health and assistant
clinical professor of medicine at UC San Diego School of Medicine.
“Our study results show a gap in the appropriate treatment of
AF patients at risk for stroke. The findings also highlight the critical need
for cardiology specialists to adhere to standardized recommendations regarding
the use of oral blood thinners instead of aspirin.”
Health issues related to coronary artery disease (blockages of
the heart arteries), including hypertension, dyslipidemia (abnormal amounts of
fats in the blood) or a prior heart attack were associated with more frequent
prescription of aspirin only; being male, a higher BMI, a prior stroke and
congestive heart failure were associated with more frequent prescription of
blood thinners.
“The high rate of an aspirin-only prescription for AF patients
with coronary artery disease and other stroke risk factors is concerning,” said
Hsu. “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.”
Hsu and his team also found approximately one-third of AF
patients in the study without significant coronary artery disease were
prescribed both a blood thinner and aspirin, placing them at higher risk for
bleeding without any evidence of benefit.
“The combination of drugs does not necessarily reduce
cardiovascular events and stroke in an AF patient population and likely
increases the risk of bleeding," he said.
“Even the most knowledgeable physicians may find themselves in
a bind when encountering a patient who needs antiplatelet drugs, such as aspirin,
due to coronary disease and blood thinners for atrial fibrillation,” said
senior author Gregory Marcus, MD, cardiologist and endowed professor in AF
research at UC San Francisco School of Medicine.
“While a large proportion of AF patients meeting the
guidelines for stroke prevention medications fail to receive them, a lack of
sufficient data regarding the clinical benefit among those with strong
indications for both antiplatelet drugs and anticoagulants may in part be to
blame.”
Both Hsu and Marcus say concerns for bleeding may be the
biggest reason for the underutilization of appropriate blood thinners in AF
patients. However, the perception that aspirin by itself is sufficient or that
the risk of aspirin plus a blood thinner is not worth the benefit may also be
driving forces.
Both researchers said
more studies evaluating cardiovascular outcomes in AF patients prescribed
aspirin-only versus oral blood thinners (or in combination) are needed.
Co-authors include: Thomas M. Maddox and Kevin Kennedy, VA
Eastern Colorado Health Care System and University of Colorado School of
Medicine; David F. Katz and Lucas N. Marzec, University of Colorado School of
Medicine; Steven A. Lubitz, Cardiac Arrhythmia Service and Cardiovascular
Research Center, Massachusetts General Hospital; Anil K. Gehi, and ll Mintu P.
Turakhia, University of North Carolina.
This research was funded, in part, by the American College of
Cardiology National Cardiovascular Data Registry.
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