Clot-busting drug treatment, when administered to patients after a stroke, appear to work more effectively if the patient was already on an anti-platelet medication. However, this might also increase the risk for bleeding within the brain. These are the conclusions of an article to be released in the May 2008 print issue of the Archives of Neurology, one of the JAMA/Archives journals.

The administration of tissue plasminogen activator (tPA) to dissolve blood clots has been associated with improved outcomes in some stroke patients. However, the medicantion itself is associated with a 10-fold increas in risk of symptomatic brain hemorrhage, or bleeding. Antiplatelet medications, including aspiring, could further increase this risk because the function of these drugs impairs the work of cells that are essential in forming blood clots.

Maarten Uyttenboogaart, M.D., and colleagues at the University of Groningen, Groningen, the Netherlands, examined 301 patients who were given tPA following a stroke between 2002 and 2006. Of these patients, 89 hd used antiplatelet drugs before tPA.

Of the patients receiving antiplatelet therapy, 13.5% (12 patients) suffered symptomatic brain hemorrhages. In contrast, only 2.8% (6 patients) of those who had not received the additional therapy did. Thus, patients who had been taking antiplatelt therapy were at a higher risk for symptomatic brain hemorrhages.

The authors point out that this was not the only outcome, as there were many positive aspects of this therapy. “Despite this increased risk, prior antiplatelet therapy increased the odds of a favorable outcome.” This was defined as an ability to carry out daily activities independently after three months. This means that the positive effects could outweigh the negatives. “Therefore, our study suggests that tPA treatment should not be withheld from patients receiving antiplatelet therapy.”

Aspirin can remain active in the body for four to six days, and could help prevent additional blood vessel blockage after tPA therapy, which would explain the improved outcomes. “Larger prospective studies are warranted to further investigate the influence of antiplatelet therapy on outcome after thrombolytic therapy for acute ischemic stroke,” the authors conclude.

Safety of Antiplatelet Therapy Prior to Intravenous Thrombolysis in Acute Ischemic Stroke
Maarten Uyttenboogaart, MD; Marcus W. Koch, MD; Karen Koopman, MD; Patrick C. A. J. Vroomen, MD, PhD; Jacques De Keyser, MD, PhD; Gert-Jan Luijckx, MD, PhD
Arch Neurol. 2008;65(5):
doi:10.1001/archneur.65.5.noc70077
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Written by Anna Sophia McKenney