Window of Time Greater for Treating Stroke
The study, published this week in the New England Journal of Medicine, suggests that patients benefit from intravenous tissue plasminogen activor (tPA) as long as four and a half hours after the onset of a stroke.
"With more than 750,000 strokes in this country every year, being able to extend the window means there are thousands more people who can be treated," Sattin says.
The drug breaks up the blood clot that causes an ischemic stroke by blocking an artery in the brain. The previous benchmark for tPA use was three hours. After that, doctors worried about bleeding in the damaged part of the brain. But the study concluded there was more benefit than risk in administering tPA during the extra hour and a half. Of 821 patients in the study, those who received tPA between three and four and a half hours after the stroke were more likely to survive, and had less disability three months later than those who received a placebo.
"Does this mean we can relax? No,"’ Sattin continues. "With every minute that goes by, our chances for success go down."
In an accompanying editorial, stroke expert Dr. Patrick Lyden of University of California-San Diego made that point, as well.
"The very real peril of (this) data is that some may take an even more leisurely approach to treating acute stroke," he writes. "Nothing could be more wrong . . .it is very clear that our focus must remain on the door-to-needle time. Every minute matters during a stroke."
Sattin, and fellow UW health neurologists Marcus Chacon and Matthew Jensen, did stroke fellowship training under Lyden at San Diego.
University of Wisconsin Hospital and Clinics has been designated as a Primary Stroke Center by the Joint Commission, currently its highest award. UW Hospital's Comprehensive Stroke Center has a goal of identifying a potential stroke patient within 10 minutes of arrival, getting the patient to a scan for diagnosis within a half hour, and into treatment within an hour.
Sattin said that while he doesn't expect the FDA to officially raise the three-hour limit on tPA intravenous use, the study "provides robust scientific evidence" that tPA can be used a bit longer. Some, but not all, previous studies had also suggested this, but this large scale, double-blind, clinical trial is more definitive.
"Now we're on much more solid ground to advocate tPA in a longer window," he said. "It gives the physician down in the clinical trenches another weapon."
But the first weapon is still time itself. It's key to recognize the signs of stroke, including:
- The sudden onset of weakness, especially on one side
- Sudden loss of vision, balance or speaking
- Sudden headache with no known cause
Date Published: 09/29/2008