Lead researcher Dr. Chelsea Kidwell, a professor of neurology and director of the Stroke Center at Georgetown University in Washington, said the study also found using advanced computerized tomography scans or magnetic resonance imaging prior to treatment did not help identify patients most likely to benefit from treatment.
The only government-approved and research-proven treatment for a blockage-caused -- ischemic -- stroke is tissue plasminogen activator, or tPA, known as the clot-busting drug. It 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," Kidwell said in a statement.
Dr. Reza Jahan, co-principal investigator for the trial and associate professor at the University of California, Los Angeles, said the study found no data that imaging -- CT and MRI -- 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," Jahan said.
The findings were presented at the American Stroke Association's International Stroke Conference.