A technique that can predict — with 95 percent accuracy — which stroke victims will benefit from intravenous, clot-busting drugs and which will suffer dangerous and potentially lethal bleeding in the brain has been developed by researchers. In an ischemic stroke, a blood clot is stuck in a vessel, cutting off blood flow to a portion of the brain, which will begin to die the longer the clot remains. When patients come to the hospital within a few hours of suffering an ischemic stroke, doctors quickly move to give intravenous tPA, hoping that it will dissolve the clot without causing additional damage.