New Stroke Therapies Show Promise
FRIDAY, Feb. 22 -- Several new studies point to the promise of new ways to treat different types of stroke.
The research was presented during a teleconference Friday at the American Stroke Association's International Stroke Conference in New Orleans.
The first trial found some benefit when tPA, the only approved therapy for acute ischemic stroke, was given outside the usual three-hour treatment window. Patients in this Australian trial who were given tPA three to six hours after having a stroke had increased restoration of blood flow and a smaller area of the brain was deprived of blood. The study was expected to be published in the April issue of The Lancet Neurology, but was released Friday to coincide with the meeting presentation.
Ischemic stroke involves an obstruction in one of the vessels supplying blood to the brain. Currently, "clot busters" are only considered effective for the first three hours after a stroke.
"The issue is that we've got a three-hour label, and can we extend that to six hours," said study author Dr. Stephen M. Davis, of Royal Melbourne Hospital. "Based on our results, it gives a lot of encouragement that you can enrich that population. A lot of people arrive too late, and these are ones we would be targeting."
The findings are enough to warrant further trials but not to change current clinical guidelines just yet.
"This should be viewed as very encouraging, as an intermediate step that's leading to the formation hopefully of a larger study that can be more definitive and that could impact our guidelines significantly," said Dr. Philip Gorelick, moderator of the teleconference and head of the department of neurology and rehabilitation at the University of Illinois at Chicago.
A second study looked at patients in China, South Korea and Australia with acute cerebral hemorrhage, the most serious form of stroke.
"High blood pressure is a cause of intercerebral hemorrhage and is also very common at [the] acute state, and we don't know what to do about it," said study author Dr. Craig Anderson, from the University of Sydney in Australia. "We believe that having high blood pressure causes extra bleeding and expansion of blood in the brain. If we can bring blood pressure down, we may be able to arrest bleeding in the brain and bring it under control."
In fact, intensive lowering of blood pressure arrested about half a teaspoon of blood and, Anderson said, "in real life, it might have a bigger treatment effect."
Again, the authors hope the findings will lead to funding for larger trials.
A third trial found that reducing blood pressure in the 60 percent to 70 percent of patients who have elevated levels following acute stroke resulted in reduced dysphasia (communication problems) and some mortality benefits.
"These are very small numbers, and I don't want to hang too much on those results, but I think it's very encouraging, so we can probably go forward and do a much larger phase 3 study," said British study author Dr. John Potter.
For now, Gorelick said, "we continue to recommend that physicians follow American Heart Association/American Stroke Association guidelines. The blood pressure [issue] has not been resolved, and there are important questions of what to do with blood pressure. . . [although] it would be nice to have a definitive plan here and get people on blood pressure-lowering medicine."
Other studies being presented at the conference found that:
- The recently approved Penumbra device, a "vacuum cleaner" which sucks clots out of the brain, was effective for eight hours after the onset of a stroke, adding five hours to a patient's treatment window.
- Aricept (donepezil) improved several measures of executive function and processing speed in patients with a subcortical form of vascular dementia but did not improve overall cognitive scores, according to researchers from the University of Muenchen in Muenchen, Germany.
- Certain chromosomal regions may harbor genes important in assessing individuals at risk for aneurysms. "This is a critical first step if you want to find genes," said study author Dr. Tatiana Foroud, of Medical & Molecular Genetics in Indianapolis. "The ultimate goal is a genetic test to identify individuals at higher risk for aneurysm, and those individuals could have targeted and more costly screening pursued on a regular basis."
Posted: February 2008
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