UT Medical School study combines blood thinner with clot-buster for treating acute stroke patients

HOUSTON—(Aug. 14, 2006)— A blood thinner given in combination with a clot-busting drug may help acute stroke patients by restoring blood flow through blocked arteries, according to a preliminary study by a team of stroke experts at The University of Texas Medical School at Houston. The study, underwritten by a grant from the National Institutes of Health, is published in the August issue of Archives of Neurology, one of the JAMA/Archives journals.

In the study, patients received a low dose of the blood thinner argatroban just after receiving a regular dose of recombinant tissue plasminogen activator (rtPA), which works to dissolve the blood clot that causes an ischemic stroke, the most common type of stroke.

But rtPA works only in about half of the patients who receive the drug within three hours of the onset of stroke symptoms, which include numbness, weakness or paralysis of the face, arm or leg, especially on one side of the body; vision problems; confusion; difficulty in speaking or walking; dizziness and severe headache. The study sought to discover if argatroban, shown in animal studies to speed the opening of vessels and prevent recurring blockages, could safely enhance the effects of rtPA in more stroke patients without causing severe bleeding.

“Everybody has been focused on the risks of rtPA, which include bleeding,” said James C. Grotta, M.D., professor and chairman in the Department of Neurology and director of the Stroke Program at the UT Medical School. “To me, the question is how to amplify the benefit. This is the first drug trial that attempts to amplify the effect of rtPA and according to the results it does appear worth further study.”

The initial safety trial included 15 stroke patients. They received the standard dose of rtPA intravenously an average of 118 minutes after symptoms began. Within one hour of the rtPA treatment, patients received a dose of argatroban, followed by a continuous 48-hour infusion.

Physicians closely monitored patients for signs of excessive bleeding and all but one participant, who showed early signs of hemorrhage, received the full dose of argatroban. The physicians used transcranial Doppler imaging to monitor blood vessel blockages.

Two patients experienced hemorrhage, of which one was severe. Grotta said this was within expected safety limits. Another patient had asymptomatic bleeding. One person died of natural consequences of the stroke.

Within two hours of medical treatment, six patients experienced recanalization (re-opening of the arteries) and four patients had partial recanalization. Three of those patients experienced blockage recurrence. Those results were better than an earlier study using only rtPA. Grotta said the use of a blood thinner in combination with rtPA now is being studied in the second phase of the trial, which will include 50 patients.

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Deborah Mann Lake

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University of Texas Medical School at Houston

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