Targeted Clot-Busting Stops Stroke Damage

The technique, known as intra-arterial thrombolysis, involves threading a catheter with clot-busting medication such as tissue plasminogen activator (tPA) through a large blood vessel in the groin up to the brain. Using imaging tools and contrast dye, doctors pinpoint the precise location of the brain blockage and deliver the medication to that spot. Researchers reviewed the medical records of 90 acute stroke patients treated with the technique at UCLA Medical Center between July 1992 and June 2000. Subjects were an average age of 69; 53 percent were female and 53 percent also had atrial fibrillation at the time of their stroke.

Atrial fibrillation is a disorder in which the heart’s upper chambers do not constrict properly, sometimes leading to the formation of blood clots. A blood clot can cause a stroke if it dislodges from the heart wall, enters the blood stream and encounters a narrowed artery in the brain.

About 2 million Americans have atrial fibrillation and about 15 percent of strokes occur in people with the condition. Under-treated atrial fibrillation is a well-recognized risk factor for more severe, and debilitating strokes.

"Atrial fibrillation is associated with increased stroke severity and a greater stroke death rate," says David S. Liebeskind, M.D., lead author of the study and clinical instructor at the University of Pennsylvania Medical Center’s Comprehensive Stroke Center. "Intra-arterial thrombolysis may be of substantial benefit for these individuals by opening arteries more frequently and permitting treatment up to six hours after symptom onset."

Intravenous tPA for acute stroke can be administered only during a three-hour window of time after stroke onset. Intra-arterial thrombolysis can be performed up to six hours after a stroke’s onset. However, extra time is needed to assemble a team of medical personnel with special expertise and training.

In the study, 40 percent of the group showed good functional outcomes after intra-arterial thrombolysis – only slight disability and adequate ability to look after their own affairs without assistance – one week after the stroke.

"We found intra-arterial thrombolysis opened blocked arteries in 67 percent of acute stroke patients with atrial fibrillation. Traditional intravenous delivery of clot busters opens arteries in 30 to 40 percent of all patients," says Liebeskind.

The investigators cautioned that brain hemorrhage occurred in 25 percent of the group. Hemorrhage rates were higher among those with atrial fibrillation and in-hospital death rates were also higher – 19 percent compared to 7 percent for those without atrial fibrillation. The brain hemorrhage rate for intravenous tPA is 6 percent.

Liebeskind says it is a promising treatment for ischemic stroke patients with atrial fibrillation, although the technique remains experimental.

He also notes that the study raises red flags about whether individuals with atrial fibrillation are getting adequate treatment before they have an acute stroke.

"At the time of admission, only 30 percent of individuals known to have atrial fibrillation were being treated in accordance with American Heart Association/American College of Chest Physician guidelines," he says. "And among those on blood thinning medications because of atrial fibrillation before their stroke, all were treated at below optimal doses."

Other authors are Jeffrey L. Saver, M.D.; Gary R. Duckwiler, M.D.; Chelsea S. Kidwell, M.D.; Joaquin Carneado; Sidney Starkman, M.D.; Paul M. Vespa, M.D.; Y. Pierre Gobin, M.D.; Reza Jahan; Fernando Vinuela, M.D.; and Scott E. Kasner, M.D.