The internationally recommended alteplase dosage for treating acute ischemic stroke is 0.9 mg/kg, according to the report in the January 20th online issue of Stroke. In Japan, however, based on encouraging data from the Japan Alteplase Clinical Trial (J-ACT) in 2002 to 2003, the Ministry of Health, Labor, and Welfare approved the use of the 0.6-mg/kg dose.
The Ministry stipulated, however, that angiography should be done to document the efficacy of the lower dose for recanalization. The present study, J-ACT II, provides the angiographic follow-up data from 57 stroke patients.
All were treated with 0.6 mg/kg of alteplase within 3 hours of documented middle cerebral artery occlusion.
According to lead author Dr. Etsuro Mori, from Tohoku University Graduate School of Medicine, Sendai, and colleagues, MR angiography showed recanalization in 51.7% of patients at 6 hours and 69.0% at 24 hours, the report indicates. Ten patients (17.5%) had delayed recanalization.
Roughly 47% of patients had a favorable clinical outcome, defined as a modified Rankin Scale score of 0 to 1 at 3 months after stroke onset. No patients had symptomatic intracranial hemorrhage within 36 hours. Eleven patients had asymptomatic hemorrhage between 24 and 36 hours.
On multivariate analysis, recanalization on 6- and 24-hour MR angiography increased the odds of a favorable outcome by 6.0- and 21.2-fold, respectively. A better baseline National Institutes of Health Stroke Scale score was also predictive of a favorable outcome.
“Early recanalization of an occluded middle cerebral artery can be provoked by 0.6 mg/kg intravenous alteplase and may induce a favorable clinical outcome,” the authors conclude. “The rates of recanalization and a favorable outcome are comparable to that previously reported with the 0.9-mg/kg dose.”