HONOLULU, Feb. 8, 2013 — In the first comparison of mechanical devices versus standard medical care for clot-caused strokes, mechanical clot removal showed no benefit over standard medical care, according to late-breaking science presented at the American Stroke Association’s International Stroke Conference 2013.
Furthermore, using advanced CT scans or magnetic resonance imaging (MRI) prior to treatment didn’t help identify patients most likely to benefit from treatment, researchers found.
The only FDA-approved and research-proven treatment for a blockage-caused (ischemic) stroke is tissue plasminogen activator (tPA), which must be given within 3-4.5 hours of the onset of symptoms. For those who arrive later or whose obstructions don’t respond to tPA, researchers hoped that mechanical clot removal would possibly result in better outcomes.
“The hope was, and to some degree still is, that if you pull out the clot within a certain period of time and there is salvageable brain tissue, there will be better outcomes,” said Chelsea Kidwell, M.D., lead researcher and professor of neurology and director of the Stroke Center at Georgetown University in Washington, D.C.
“We found no data that imaging could help select patients for treatment and did not show an overall benefit of physically removing the clot. However, further studies are needed because there are new devices that open up vessels better and faster, and with fewer complications, than the first generation devices used in our trial,” said Reza Jahan, M.D., co-principal investigator for the trial and associate professor of interventional neuroradiology at the University of California in Los Angeles.
The 22-center Mechanical Retrieval and REcanalization of Stroke Clots Using Embolectomy (MR RESCUE) trial included 118 patients, average age 65.5, treated within 8 hours after experiencing an ischemic stroke in one of the large blood vessels carrying blood to the front of the brain (the most common location for this type of stroke).
Physicians measured regions of the brain that were in danger of dying, but might be salvaged if blood flow was restored quickly, with specialized evaluation of CT scans or MRI.
Researchers divided patients into those showing a large area of at-risk but salvageable brain tissue near the clot and those without. They then randomly assigned patients in both groups to receive either standard medical treatment (according to current guidelines) or to have their clot removed by the MERCI Retriever (a tiny corkscrew device) or the Penumbra System (an aspiration device).
“The data are encouraging as far as safety, but we really need randomized controlled trials of newer devices to see if they improve outcome,” Kidwell said. “At this point we can say that the MR RESCUE trial failed to demonstrate that advanced imaging techniques identify patients who will benefit from mechanical clot retrieval for acute ischemic stroke and failed to demonstrate superiority of embolectomy compared with standard medical care. If you experience signs of stroke, the important thing is to get to a stroke center in time to qualify for the only proven treatment — tPA.”
Other co-authors are Jeffrey Gornbein, Dr.P.H.; Jeffry R. Alger, Ph.D.; Val Nenov, Ph.D.; Zahra Ajani, M.D.; Lei Feng, M.D., Ph.D.; Brett C. Meyer, M.D.; Scott Olson, M.D.; Lee H. Schwamm, M.D.; Albert J. Yoo, M.D.; Randolph S. Marshall, M.D., M.S.; Philip M. Meyers, M.D.; Dileep R. Yavagal, M.D.; Max Wintermark, M.D.; Judy Guzy, R.N.; Sidney Starkman, M.D.; and Jeffrey L. Saver, M.D. Author disclosures are on the abstract.
The National Institutes of Health, National Institute of Neurological Disorders and Stroke funded the study.
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Statements and conclusions of study authors that are presented at American Stroke Association scientific meetings are solely those of the study authors and do not necessarily reflect association policy or position. The association makes no representation or warranty as to their accuracy or reliability. The association receives funding primarily from individuals; foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific association programs and events. The association has strict policies to prevent these relationships from influencing the science content. Revenues from pharmaceutical and device corporations are available at www.heart.org/corporatefunding.
Note: Actual presentation is 10:48 a.m. HT Friday, Feb. 8, 2013.
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