NEW ORLEANS — A lower-than-usual intravenous dose of tissue plasminogen activator may still be effective for treating patients with acute stroke, according to a review of 83 patients.
“A low dose of 0.6 mg/kg was safe and effective,” Marilyn M. Rymer, M.D., and associates reported in a poster at the 30th International Stroke Conference.
The usual dose of intravenous tissue plasminogen activator (TPA) is 0.9 mg/kg, based on the regimen's safety and efficacy in the original thrombolytic therapy trial by the National Institute of Neurological Disorders and Stroke (NINDS) and reported in 1995, according to Dr. Rymer, medical director of the stroke center at Saint Luke's Hospital in Kansas City, Mo., and colleagues.
The idea of treating patients initially with a 0.6-mg/kg IV dose began with the Interventional Management of Stroke (IMS) trial, which reserved a 0.3-mg/kg dose for subsequent intraarterial delivery. Hospitals in the Mid America Brain and Stroke Institute (MABSI) regional network now routinely use the 0.6-mg/kg dose of intravenous TPA, and then send the patient by ambulance to a hospital or a referral center for further evaluation, Dr. Rymer and her associates reported in a poster at a conference sponsored by the American Stroke Association.
Dr. Rymer and her colleagues identified 83 patients who received the 0.6-mg/kg dose only in the MABSI database, as well as another 50 patients who received a 0.6-mg/kg dose initially that was later followed by intraarterial treatment with 0.3 mg/kg of TPA to assess in-hospital mortality and patients' NIH Stroke Scale (NIHSS) score at discharge. This analysis used a discharge NIHSS of 4 or less and 2 or less as criteria for good outcomes.
The in-hospital mortality rates were 6% in the 83 patients treated with 0.6 mg/kg of TPA only and 12% in all 133 patients in the MABSI database. The 90-day mortality rates were 17% in the original NINDS trial and 16% in the IMS trial.
At hospital discharge, 71% of the patients who received just the 0.6-mg/kg dose had an NIHSS of 4 or less, and 63% had a score of 2 or less. In the entire MABSI group, 62% had discharge scores of 4 or less and 48% had scores of 2 or less. In the NINDS and IMS studies, NIHSS were measured 90 days after treatment; 31% and 28% of patients, respectively, had scores of 1 or 0 at that time, the investigators reported.