| |
|
Headlines:
|
 |
Back to Neurology Articles
|
|
|
Intracranial stenosis is caused by atherosclerosis - fatty deposits
that build up on the inner walls of the arteries and restrict blood
flow.
|
|
| |
|
|
| |
|
|
| |
|
|
| |
|
|
To reduce the risk of stroke, partial blockage of arteries in the
brain (intracranial stenosis) has for decades been treated with drugs
such as aspirin and warfarin that reduce blood clotting. However,
doctors have never had good evidence for choosing one therapy over the
other. Now, results of a double-blind, randomized clinical trial show
for the first time that aspirin works as well as warfarin with fewer
side effects.
The study was funded by the National Institute of Neurological
Disorders and Stroke (NINDS), part of the National Institutes of Health
(NIH).
"This trial is good news. A simple low-cost drug works just as well as
one that requires complicated and expensive monitoring and dose
adjustments,"
says John R. Marler, M.D., the Associate Director for Clinical Trials at
NINDS. The study appears in the March 31, 2005, issue of the New England
Journal of Medicine.*
Intracranial stenosis is caused by atherosclerosis -- fatty deposits
that build up on the inner walls of the arteries and restrict blood
flow.
Intracranial stenosis causes about 10 percent of the 900,000 strokes and
transient ischemic attacks (TIAs) in the United States each year. TIAs
are transient strokes that last only a few minutes and occur when the
blood supply to part of the brain is briefly interrupted. People with a
stroke or TIA due to intracranial stenosis have a greatly increased risk
of a second stroke – as much as 15 percent per year. Studies in the
1950s suggested that anticoagulants (a class of drugs that reduce blood
clotting), such as warfarin, can reduce the risk of stroke in people
with this disease.
In the new study, called the Warfarin Aspirin Symptomatic Intracranial
Disease (WASID) trial, investigators at 59 medical centers across the
United States, led by Marc I. Chimowitz, M.D., of Emory University in
Atlanta, compared warfarin to 1300 milligrams (mg) per day of aspirin in
a total of 569 patients for an average of 1.8 years. All of the patients
had a greater than 50 percent blockage of a major intracranial artery
and had experienced a TIA or non-disabling stroke within the 90 days
prior to their enrollment in the study.
The investigators found that about 22 percent of the patients had a
subsequent ischemic stroke (caused by blockage of an artery), brain
hemorrhage, or death from other blood vessel-related causes, regardless
of whether they received aspirin or warfarin. However, the rates of
major hemorrhage and death from all causes were significantly higher in
the patients treated with warfarin (event rates for aspirin compared to
warfarin, respectively, were 3.2 percent vs. 8.3 percent for major
hemorrhage and 4.3 percent vs. 9.7 percent for death). Enrollment in the
study was terminated earlier than originally planned on the
recommendation of an independent Data and Safety Monitoring Board
because of concern for the safety of the patients given warfarin.
Since warfarin treatment is a more expensive and complicated therapy
than aspirin, not using warfarin and preventing the bleeding
complications associated with it would save more than $20 million per
year in the United States, Dr. Chimowitz estimates.
"The results of this study are only relevant to people with intracranial
stenosis," Dr. Chimowitz notes. People who are receiving warfarin for
other conditions, such as an irregular heart rhythm (called atrial
fibrillation) or clots in the legs or lung, should not stop taking the
drug, as studies have found that it is the best option in those
conditions, he cautions.
The dose of aspirin used in this study – 1300 mg – is much higher than
the daily doses typically prescribed, which range from 81 to 325 mg.
While there is some concern that doses of 1300 mg aspirin may increase
the risk of gastrointestinal bleeding, the investigators chose this dose
because it was the only amount for which earlier studies had provided
good preliminary data. "This is the only dose we know is as effective as
warfarin for this disease, since it was the only dose studied. We just
don't know how other doses of aspirin would stack up," says Dr.
Chimowitz.
The major bleeding risk on high dose aspirin in WASID was similar to the
major bleeding risk in other stroke trials that have evaluated lower
doses of aspirin (e.g. 325 mg per day), he adds. Most experts believe
there are no advantages to aspirin doses greater than 325 mg for stroke
prevention, and the U.S. Food and Drug Administration-approved dose of
aspirin for prevention of vascular events is 50-325 mg. Patients should
consult their physicians before beginning any long-term or high-dose
aspirin treatment regimen.
Even with treatment, the rates of ischemic stroke in this clinical trial
were substantially higher than in stroke prevention trials that have
evaluated aspirin and warfarin in patients with other causes of stroke.
This underscores that patients with intracranial stenosis are at
particularly high risk for stroke and that better therapies are needed,
the investigators note.
###
The NINDS is a component of the National Institutes of Health within the
Department of Health and Human Services and is the nation's primary
supporter of biomedical research on the brain and nervous system.
*Chimowitz MI, Lynn MJ, Howlett-Smith H, Stern BJ, Hertzberg VS, Frankel
MR, Levine SR, Chaturvedi S, Kasner SE, Benesch CG, Sila CA, Jovin TG,
Romano JG, for the Warfarin Aspirin Symptomatic Intracranial Disease
(WASID) Investigators. "Comparison of warfarin and aspirin for
symptomatic intracranial arterial stenosis." New England Journal of
Medicine, March 31, 2005, Vol. 352., No. 12, pp. 1305-1316.
|
|
|
|
Are you a doctor or a nurse?
Do you want to join the Doctors Lounge online medical community?
Participate in editorial activities (publish, peer review, edit) and
give a helping hand to the largest online community of patients.
Click on the link below to see the requirements:
Doctors Lounge Membership
Application |
|
|
|
send
to a friend
printer
friendly version
