The clot-busting compound tPA, approved by the federal government for use against strokes in 1996, has opened a new era in stroke treatment. Used within a 3-hour window after a stroke, the drug improves the chances for a full recovery from 33 percent to 50 percent. But a new study confirms that beyond that 3-hour window, the drug can be ineffective or even harmful to patients. Wayne Clark, M.D., director of the Oregon Stroke Center at Oregon Health Sciences University, is presenting results of the "ATLANTIS" study at the American Heart Association's annual Stroke Conference in Nashville, Tenn. The research was funded by Genentech.
"After that 3-hour window, this study shows tPA has no benefit in improving stroke recovery," said Clark. "In addition, there's a 7 percent risk the stroke will get worse if the drug is used after three hours, including a 3 percent chance of early death." This study confirms that beyond three hours, tPA can cause dangerous bleeding in the brain. The Oregon Stroke Center was the leading enrolling site in the country in this multi-center study involving 542 patients.
Currently, Clark said tPA is used in about 5 percent of the 500,000 stroke cases across the U.S. annually. "This is a very effective drug that could be used in a lot more stroke cases if patients got to the hospital within three hours," said Clark. "This study firms up the guidelines for using TPA. The bottom line is it should not be used after three hours. A quick response can make a life or death difference for these patients."