Blood-Thinning Drug's Benefit in Stroke Prevention

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American Heart Association journal report: Blood-thinning drug's benefit in stroke prevention extends to elderly with irregular heartbeat

DALLAS, April 7 -- Using a blood-thinning drug in elderly people with an irregular heartbeat may provide stroke-preventing benefits that had previously been found only in younger people, according to a report in today's Stroke: Journal of the American Heart Association.

Atrial fibrillation is an irregular heart rhythm, or arrhythmia, affecting about two million Americans, according to the American Heart Association. The condition leads to nearly 90,000 strokes or mini-strokes (transient ischemic attacks) each year. One way to treat atrial fibrillation is with a clot-inhibiting drug called warfarin.

Elderly people are, by virtue of their age, at greater risk of stroke. Additionally, warfarin must be used cautiously in those over 80 years of age because of the increased risk of internal bleeding, one of the major potential side effects of using the drug.

"Ironically, because of their higher risk of stroke, the net benefit of blood-thinning therapy may be greater in the elderly than in those who are younger," says the study's lead author, Brian F. Gage, M.D., assistant professor of medicine at Washington University in St. Louis and director of Barnes-Jewish Hospital Blood Thinner Clinic.

Prior studies have shown the usefulness of warfarin in middle-aged people who have the heart rhythm disorder. Because the elderly aren't usually included in clinical trials, the usefulness of warfarin in the elderly was still unclear. Gage says this is the first study to find a statistically significant benefit of using warfarin in the elderly.

Researchers studied 597 Medicare beneficiaries who had atrial fibrillation and found that when compared to those not receiving the drug, people getting warfarin had a 24 percent reduced risk of death and hospitalizations from stroke or mini-stroke. Only about half of the ideal candidates for the drug received it.

"Among people in this age group who have atrial fibrillation -- and if they don't have any contraindications -- we found that warfarin is the best drug for them," says Gage. "We found that the benefit of warfarin for younger people with atrial fibrillation also extends to frail, elderly people."

Researchers determined that by increasing the appropriate use of warfarin by just 5 percent, 91 deaths or hospitalizations could be prevented among the 20,000 Missouri Medicare beneficiaries who are annually hospitalized with atrial fibrillation.

Echoing previous research, Gage and his colleagues found that the use of warfarin was very low in those patients who could most benefit from it. Only 328 of the 597 people studied (55 percent) were prescribed clot-inhibiting therapy at hospital discharge. Only 34 percent received warfarin, while the other 21 percent were put on aspirin therapy.

Those who were older, female or lived in rural areas were less likely to receive drugs such as warfarin or aspirin. The researchers say it is not clear why women may be undertreated and add that the therapy is effective in both men and women.

The study found that people who received warfarin had a 24 percent relative risk reduction of death or hospitalization for stroke or mini-stroke compared to a 5 percent relative risk reduction in those who received aspirin.

"In light of the evidence that stroke can be prevented by antithrombotic therapy, the low use of warfarin and aspirin in this population is disappointing," says Gage.

The researchers say there are two main reasons for the low use of antithrombotic therapy: inconvenience and physicians' fear of causing excessive bleeding. Patients receiving warfarin must be regularly monitored to ensure they are not at increased risk for bleeding. Special clinics have been developed for the specific purpose of monitoring those on blood-thinning treatment. However, it can be difficult for those in rural areas to make trips to the clinics.

"On the horizon, I see some potential for removing these barriers," says Gage. "Home monitors, similar to what diabetes patients use to check their glucose levels, are being developed so that people can get the benefits of antithrombotic drugs in an easy and safe manner. Blood-thinner clinics can also help to facilitate the use of warfarin."

Co-authors are Michael Boechler, Ph.D.; Amy L. Doggette, M.A.; Gary Fortune, D.O.; Greg C. Flaker, M.D.; Michael W. Rich, M.D.; and Martha J. Radford, M.D.

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NR00-1129 (Stroke/Gage)

Media advisory: Dr. Gage may be reached by phone at (314) 454-8369, by fax at (314) 454-5554 or by e-mail at [email protected]. (Please do not publish numbers.)