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May 8, 2000
News this month
Clot-dissolving treatment for stroke investigated
Strokes afflict
more than 600,000 Americans each year. About 43 percent of these
are women, but women account for more than 60 percent of stroke
deaths. The great majority of the time, the culprit is some kind
of clot that obstructs the flow of blood through an artery, where
for a variety of reasons, blood-starved brain cells don't die right
away. If the offending clot is broken up quickly enough, normal
blood flow is restored and the brain is spared.
"tPA
is
the only medication approved
for the treatment of acute ischemic stroke."
In 1996, the U.S. Food and Drug Administration approved a clot-dissolving
drug called tissue-type plasminogen activator (tPA) for use in stroke
patients. It is, to date, the only medication approved for the treatment
of acute ischemic stroke. The approval was based on the results of
a clinical trial sponsored by the National Institute of Neurological
Disorders and Stroke (NINDS) that found substantial and statistically
significant benefits in stroke patients.
Proper use of tPA
The use of tPA in appropriate patients has been strongly endorsed
by the American Heart Association, the National Stroke Association
and the American Academy of Neurology, but only a small fraction of
eligible patients currently receive the therapy. Physicians have expressed
a fear that the risk of hemorrhage may be higher in clinical practice
than the 6.4 percent experienced in the NINDS-sponsored clinical trial.
"tPA
must be administered within three
hours of the first symptom of a stroke
"
Strict guidelines apply to tPA usage. It must be administered within
three hours of the first symptom of a stroke; and, in addition to
this three-hour treatment window, patients who have been taking blood
thinners, whose blood pressure is out of control or who have a few
other health problems are not supposed to receive tPA.
When administered by experienced doctors, tPA can improve the recovery
of stroke patients, according to two studies published in the Journal
of the American Medical Association in March. But these
studies find that physicians often give the medication to patients
who shouldn't receive it and sometimes don't administer it quickly
enough.
STARS Study
The FDA mandated the Standard Treatment with Alteplase to Reverse
Stroke (STARS) Study to assess the safety of tPA use in actual clinical
practice. The study involved close to 400 stroke patients who received
tPA between February 1997 and December 1998 at 57 medical centers
in the U.S. Nearly all of the physicians involved were experienced
with tPA, having participated in other studies with the medication.
In the STARS Study, 3.3 percent had bleeding in the brain after treatment
with tPA, a better result than the 6.4 percent who experienced bleeding
in the brain in the earlier, NINDS-sponsored clinical trial. In the
STARS Study, approximately one-third of the treated patients had favorable
outcomes.
However, these researchers also found that about a third of the time,
physicians violated the treatment guidelines for using tPA, often
giving it after the three-hour limit and when patients had taken blood
thinners, both contraindications based on treatment guidelines.
"
patients did better overall, but it
should be a wake-up call to physicians that we need to treat them
sooner in the ER."Dr. Gregory
Albers, Stanford Univ.
"I think the findings should be a reassuring message to consumers
since one of the most convincing things about the study was that patients
did better overall, but it should be a wake-up call to physicians
that we need to treat them sooner in the ER," said Dr. Gregory
Albers of Stanford University who led the STARS study.
Cleveland area study
Researchers in the other study were interested in investigating the
use of tPA in Cleveland area hospitals among physicians who were not
necessarily part of major stroke centers experienced in the use of
tPA. The retrospective study involved 3,948 patients with a primary
diagnosis of ischemic stroke admitted between July 1997 and June 1998
to 29 community hospitals in the Cleveland area.
Only 70 of these patients, just 1.8 percent, were given tPA, suggesting
that eligible patients were probably not being treated. Treatment
guidelines were violated in half of those who got the drug, and
those violations contributed to a slightly higher death rate and more
cases of bleeding in the brain.
Both studies showed physicians seem to be giving tPA at the latest
possible minute, with patients getting the medication, on average,
two hours and 44 minutes after symptoms began.
According to Dr. Irene Katzan, the lead researcher in the second study
who is with the Cerebrovascular Center of the Cleveland Clinic, this
study suggests education is needed for all physicians in all specialties.
"While I think the report is important, it should serve to remind
us of the importance of following the national guidelines." Patients
should be encouraged to seek early care, she emphasized, since the
consequences of stroke are so devastating.
Risk factors for stroke:
- Age 60 or older
- Previous stroke
- High blood pressure
- Smoking
- Heart disease
- Diabetes
- Sedentary lifestyle
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tPA offers hope for recovery
The anti-clotting
drug tPA has been used in heart attacks for several decades, but
we have been cautious about using it for stroke patients because
of concerns about bleeding in the brain. The study conducted in
1995 by the National Institute of Neurological Disorders and Stroke
(NINDS) demonstrated that if patients were carefully selected to
minimize the risk of bleeding and treated within three hours with
a slightly lower dose of tPA than is used for heart attacks, it
can improve outcomes. If the drug is used according to guidelines,
tPA improves the odds of being cured from stroke by 30 percent.
"
tPA improves the odds of being cured from stroke by
30 percent."
The guidelines exclude patients with very high blood pressure, those
who take blood thinners such as coumadin and those who have recently
had surgery. Even if the guidelines are followed, the original study
showed the drug does carry an increased bleeding risk of 6.4 percent
particularly among elderly patients and those who had experienced
very severe strokes.
The results of the STARS Study relieve some concern about a possible
increase in the rate of dangerous side effects when the drug moves
out of clinical trials and into real-world use. The new multicenter
study found the risk of intracranial hemorrhage after tPA treatment
does not outweigh the clear benefits of the drug for most patients.
The results indicate an even lower risk of bleeding, 3.3 percent,
than might have been expected based on earlier studies.
"
risk of intracranial hemorrhage after tPA treatment does not outweigh the clear benefits of the drug for most patients."
The Cleveland area study indicates, however, a higher risk in clinical
settings. About half of the patients treated with tPA in this study
did not meet the drugs guidelines, and the risk of bleeding,
about 16 percent, was more than double that of earlier studies.
Why the higher risk? Its difficult to say. Two major hospitals
in the Cleveland study who admitted large numbers of stroke patients
failed to use tPA on any of their patients. Some of the results may
reflect the pro- and anti-tPA camps that existed soon after the FDAs
approval of the drug in 1996.
"
how well you do depends to a large extent on two factors:
the experience of the team that treats you and how quickly you seek
help."
What you need to know
What is clear is when you seek treatment for a stroke, how
well you do depends to a large extent on two factors: the experience
of the team that treats you and how quickly you seek help. Treatment
with tPA within three hours of a stroke improves chances of complete
recovery and reduces the severity of long-term disability.
Yet because many people aren't aware that anything can be done to
treat stroke, only 5 percent of stroke victims make it to the
hospital in time to be helped. The pain of a heart attack motivates
people to call 911 right away, but someone who drops a coffee cup
or has trouble talking often goes to bed in hopes of feeling better
later. Getting to the hospital quickly is critical. Call 911 if
you think you may be having a stroke or if you are with someone
you suspect might be having a stroke. Watchful waiting only makes
it more difficult for a stroke sufferer to receive treatment
in time to prevent permanent brain damage.
Stroke symptoms include sudden onset of symptoms such as:
- Muscle weakness
or numbness often isolated on one side of the body
- Impaired speech
or inability to understand speech
- Visual loss
- Poor balance
and loss of coordination
- Severe headache
- Mental confusion
The challenge of treating
stroke patients within such a narrow time window is compounded
by the fact that tPA is not warranted in every situation. In a hemorrhagic
stroke, caused when a blood vessel in the brain ruptures and blood
pools in the surrounding tissue, tPA treatment would be very
dangerous. It could cause additional bleeding in the brain. The drug
is used to treat acute ischemic stroke only, which occurs when
a clot lodges in a blood vessel in the brain and blocks the normal
flow of blood. The oxygen-starved brain cells downstream of the obstruction
quickly begin to die.
This difference in cause and treatment make a correct yet speedy
diagnosis particularly essential. Emergency room physicians use a
CT scan to quickly visualize the brain and determine which type of
stroke is affecting the patient before deciding on a course
of treatment.
In addition to intravenous injections of tPA, there are ongoing investigational
trials assessing the effectiveness of direct injection of anti-clotting
medications into a catheter threaded through the arteries of the brain
to deliver treatment directly to the site of the clot. This approach
on appropriate patients can be used as long as six hours after the
onset of a stroke.
Prevention the best cure
There are also several new surgical and medical approaches to prevent
stroke in high-risk individuals. Blood pressure control, heart medications,
anticoagulants and dietary changes all show success. People with a
severely blocked artery to the brain may be candidates for a carotid
endarterectomy, in which surgeons scrape built-up plaque out of the
artery. A newer, less invasive procedure uses a tiny catheter to place
a titanium stent to permanently hold the artery open.
Finding the right care
Choosing a hospital with comprehensive stroke services is one way
to improve your chances of the best outcome. Quick assessment and
diagnosis in the Emergency Department by an experienced team of caregivers
can make all the difference. Check with local branches of national
organizations such the National Stroke Association or the stroke section
of the American Heart Association to determine what medical centers
in your area have the resources and volume of patients that indicate
expertise in stroke care. When you evaluate a hospital's treatment
of stroke, make sure it offers tPA. Find out what experimental trials
it participates in. Does it enroll just two patients a month or 20
in these studies?
Then if stroke occurs, don't forget to act. Most stroke patients who
got treated in time did so because they or someone nearby recognized
the symptoms and got them to the hospital in a hurry. 
Dr. Fayad is a
neurologist on staff at Yale-New Haven Hospital, associate professor
of neurology at the Yale School of Medicine, co-director of the Yale
Cerebrovascular Center and director of the Yale Vascular Neurology
Program.
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