Aspirin Lowers Stroke Risk in Peripheral Artery Disease
TUESDAY May 12, 2009 -- There haven't been enough studies to tell whether aspirin reduces the risk of heart attack and death for people with the blocked leg blood vessel condition called peripheral arterial disease, but it does cut the incidence of stroke, researchers report.
The finding comes from a meta-analysis of the not-too-many studies of aspirin use with peripheral arterial disease (PAD); it appears in the May 13 issue of the Journal of the American Medical Association.
It's not clear why PAD has been a neglected subject, said study co-author Dr. Mori J. Krantz, an associate professor of medicine at the University of Colorado. "PAD is the unloved stepchild of atherosclerosis, in that it has been understudied."
The degree of neglect was evident in numbers cited in the report. Studies of aspirin therapy in other kinds of atherosclerosis have been numerous. But the largest of the 18 studies of PAD cited in the report included just 1,276 people. The total of all the people in those studies was 5,269.
And 15 of those 18 studies were done more than 10 years ago, said Dr. Mary McGrae McDermott, a professor of medicine at the Northwestern University Feinberg School of Medicine and co-author of an accompanying editorial. "How relative they are to the PAD patient today is not clear."
Overall, those studies found a 12 percent reduction in all cardiovascular events among patients receiving aspirin therapy, compared to those who were not -- a number that did not reach statistical significance. There was no significant reduction in the death rate or incidence of heart attacks, but the incidence of nonfatal stroke was 34 percent lower in the aspirin-taking group.
"We found no evidence of harm or increased bleeding risk with aspirin," Krantz said. "We think that aspirin, for the most part, is a good treatment for atherosclerosis."
"The fact that a statistically significant reduction was not found has a lot to do with the fact that the studies were clinically underpowered," McDermott said. "Antiplatelet therapy should be used for atherosclerosis, and aspirin is certainly the cheapest antiplatelet therapy for PAD."
Antiplatelet therapy is directed at platelets, the blood cells that clump together to form clots that block arteries.
A larger study of antiplatelet therapy such as aspirin in PAD is needed to resolve any doubts, Krantz said. And, in fact, such a study is nearing completion, McDermott said. It is being done in Europe, and its leader has said that results should be available by the end of August, McDermott added.
Meanwhile, what are doctors and people with PAD to do? Pretty much what they have been doing, Krantz said.
"What I do for patients with heart disease is use aspirin," Krantz said. "For those with stroke, I use aspirin. For PAD, we vary it -- sometimes aspirin, sometimes Plavix. But even now, evidence for those combinations has not been proven. We don't know the optimum regimen for patients with PAD."
Plavix is a commonly used prescription drug used to prevent clotting.
"We don't think that anyone with PAD should be stopping their aspirin," said study author Dr. Jeffrey S. Berger, a cardiology fellow at the University of Pennsylvania. "But we need more data to show benefit with 100 percent certainty. It is well known that people with PAD need antiplatelet therapy, but it's unclear what the appropriate agent should be. It is a question that all patients need to address with their health-care providers."
Learn all about PAD from the American Heart Association.
Posted: May 2009