Results of the study were presented at a news conference on Dec. 13 held by the National Institute of Neurological Disorders and Stroke of the National Institutes of Health in Bethesda, Md., and were published in the Dec. 14 New England Journal of Medicine . The study received national attention from the media, including, among others, ABC and CBS national news broadcasts and front-page stories in The New York Times and USA Today . According to investigators in the study, timing is a critical factor. Over the past 12 years basic and clinical scientists have been working to discover the window of opportunity for emergency treatment of stroke. Based on research in animal models and clinical observations, the t-PA clinical investigators designed their highly coordinated emergency treatment program to work within the narrow time window of three hours.
Stroke occurs when blood flow to the brain is interrupted by either a blood clot or burst vessel.
Arteries blocked by a blood clot account for more than 80 percent of all strokes. More than 600 stroke patients in the national study received t-PA or placebo in emergency rooms within three hours of their first symptom. Of those, half were treated within 90 minutes. Before treatment could start, a medical team performed a CAT scan to be sure the stroke was not caused by bleeding, administered a variety of blood tests and obtained informed consent. Part one of the trial was designed to look for marked improvement in the patient's condition 24 hours after treatment.