CHICAGO (Reuters) - A study aiming to expand the three-hour time window for giving a clot-busting drug to stroke patients fell short of its goal, Australian researchers said on Friday, but the study hinted that certain stroke sufferers might still benefit from late administration of the drug.
They had hoped to prove the clot-buster known as tissue plasminogen activator or tPA would significantly reduce the spread of a stroke three to six hours after the first symptoms appeared.
Under current guidelines, the drug can only be given within three hours of the first symptoms, a restriction that leaves out all but a lucky few who get immediate help.
When given promptly, tPA can reduce permanent disability. It only works on ischemic stroke, which is caused when a blood clot chokes off blood flow to the brain.
Stephen Davis of Royal Melbourne Hospital in Victoria, Australia, wanted to see if the drug could help a subset of stroke patients with salvageable brain tissue after the three-hour time limit had passed.
He and colleagues studied 101 patients who received tPA or placebo three to six hours after their stroke started. Of these, 99 people or 86 percent were believed to have salvageable brain tissue. About half of these got tPA and half got placebo.
While the late use of the drug did not show statistically significant improvement, it did show a strong trend toward saving brain tissue, said Davis, whose study was published in the journal Lancet.
It also helped improve blood flow into the damaged area, a finding that was statistically significant.
The researchers said the study, known as EPITHET, suggests extending the time window beyond three hours could be useful for some patients.
"EPITHET provides strong encouragement but it should not change any clinical guidelines," Davis told a media briefing at the American Stroke Association's International Stroke Conference in New Orleans.
"It gives a clear message we believe as to the design of the next trial," said Davis, whose comments were broadcast on the Internet.
At the same conference, researchers said a device that suctions out blood clots helped improve blood flow to the brain in 82 percent of 125 patients studied, even eight hours after the onset of the stroke. About 40 percent of the patients showed improvement 30 days after treatment.
The study tested the Penumbra System, made by privately held Penumbra Inc. of Leandro, California, which recently won U.S. regulatory approval. It did not compare the treatment's performance to any other device or placebo.
Dr. Cameron McDougall of Barrow Neurological Institute in Phoenix, Arizona, said the device performed better than he had expected and said it might offer a safe way of treating ischemic stroke.
Editing by Stuart Grudgings