THURSDAY, Feb. 10 (HealthDay News) -- A new anti-clotting drug
works better than aspirin for stroke prevention in some patients
with the common, sometimes lethal, heart rhythm problem known as
atrial fibrillation, according to research presented Thursday.
The new drug, apixaban, is not yet approved for use by the U.S.
Food and Drug Administration. But study co-author Dr.
Hans-Christoph Diener said the pill "reduced stroke risk [in
patients with atrial fibrillation] by 55 percent, compared to
aspirin." He believes that "the results of this clinical trial will
change clinical practice."
Diener, of the department of neurology and the Stroke Center at
University Hospital Essen in Germany, presented the findings at the
annual meeting of the American Stroke Association's International
Stroke Conference in Los Angeles. The findings are also published
online Feb. 10 in the
New England Journal of Medicine.
In atrial fibrillation, an irregular beating of the heart causes
blood to pool in the heart's chambers. The heart can then "throw"
clots up into the arteries supplying blood to the brain, greatly
raising the risks for stroke.
Patients with atrial fibrillation are typically prescribed
anticoagulants such as warfarin, which is notoriously hard to
manage, Diener said at a news conference announcing the study
Anticoagulants taken orally can decrease stroke risk by up to 70
percent, according to Diener, but many patients don't comply with
the regimen. "About half of all patients refuse to take
[warfarin]," he noted, because its use is accompanied by dietary
restrictions and the need for frequent blood tests to check blood
levels of the drug. Some patients also fear the possibility of a
known hazard of warfarin, an excess risk for bleeding.
Many patients who can't or won't take warfarin do take daily
aspirin, which cuts the odds of stroke in atrial fibrillation by
about 20 percent, according to background information in the
In the new study of apixaban, researchers assigned almost 5,600
patients with atrial fibrillation and an increased risk of stroke
(due to age or prior stroke, for instance) to one of two groups:
apixaban, at 5 milligrams taken twice daily; or aspirin, with doses
ranging from 81 to 324 milligrams per day.
The study was done at 522 centers in 36 countries from late 2007
to late 2009. The researchers wanted to compare which drug was
better at preventing stroke or blockages due to blood clots
elsewhere in the body, called systemic embolism.
Among patients on apixaban, there were 51 strokes or embolisms,
or 1.6 percent per year, compared to 113 such events, or 3.7
percent, among those on aspirin.
While apixaban patients experienced 44 major bleeding events,
aspirin takers had 39, but the difference was not great enough to
be significant from a statistical point of view, Diener said.
The study was funded by Bristol-Myers Squibb and Pfizer, who are
working jointly to develop apixaban.
The drug has been shown in previous research to be better at
preventing dangerous leg blood clots and lung clots after hip
replacement surgery than an older drug, enoxaparin.
Apixaban works by blocking a crucial step in the formation of
blood clots. The study of the drug's effects on stroke prevention
was actually halted early after one year, Diener said, because of
the huge difference found between the two drugs and the superiority
The new drug isn't yet approved by the FDA and Diener couldn't
predict when that might happen. Results of another study, a
head-to-head comparison of apixaban against warfarin, is due out in
August, he said.
A 55 percent reduction in stroke risk compared to aspirin is
impressive, said Dr. Larry Chinitz, professor of medicine at the
New York University School of Medicine and director of the Heart
Rhythm Center at NYU Langone Medical Center. He reviewed the study
findings but was not involved in the research.
"I think it's a game-changer" for higher risk patients with atrial fibrillation, he said, such as those over age 70.
The new drug, if approved, ''will certainly improve the
lifestyle of patients," Chinitz said, as it won't require, as
warfarin does, frequent blood tests or dietary restriction.
Another new anti-clotting drug, Pradaxa (dabigatran), was
approved by the FDA in October 2010 for stroke prevention in those
with atrial fibrillation. It inhibits an enzyme involved in blood
To learn stroke's warning signs, head to the
American Stroke Association.