Using advancing imaging after the onset of acute stroke does not help physicians identify patients who benefit from a clot-removal procedure, according to results from the Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy (MR RESCUE) Trial published online Feb. 6 in the New England Journal of Medicine.
Patients who suffer from ischemic strike are at risk of suffering brain cell death, which can be avoided if physicians are able to quickly open the blocked artery. Intravenous issue plasminogen activator (t-PA) has been effective in dissolving clots and improving outcomes in some stroke patients, but has been less effective in patients with clots in the larger brain arteries associated with the most serious strokes.
The MR RESCUE Trial tested a different strategy--the use of a catheter threaded through an artery in the groin up to the site of the brain artery in order to removed the blockage--on patients who were enrolled at 22 centers across the U.S. within 5.5 hours of the onset of stroke.
All of the patients were given either emergency CT or MRI perfusion imaging to identify areas of reduced blood flow and areas that couldn't be salvage. The investigators proceeded on the hypothesis that patients would benefit from the clot removal procedure if a scan showed that less than 70 percent of the brain with decreased blood flow had already died.
Based on the imaging results, 118 patients randomly were either assigned to receive the clot removal procedure or standard therapy, according to medical protocols.
The researchers found that the patients who had what was hypothesized to be a favorable imaging result actually had the same level of disability at 90 days, no matter whether they had the standard therapy or the invasive clot removal procedure.
"Despite a lack of evidence showing that these clot-removal devices improve outcomes, they are already widely used in patients who are not able to get to the hospital in time to receive t-PA," Walter J. Koroshetz, M.D., deputy director of the National Institute of Neurological Disorders and Stroke, which funded the trial, said in an announcement. "Though some patients have had dramatic improvements with clot removal, it has not been shown effective in this or another larger study, the Interventional Management of Stroke, which was halted early because it did not find the procedure to be of significant benefit.
Koroshetz added that neuroimaging advances are promising and "may someday help to identify who will benefit from a device-based approach."