Magazine article Clinical Psychiatry News

MRI Opens Thrombolysis Window after Stroke

Magazine article Clinical Psychiatry News

MRI Opens Thrombolysis Window after Stroke

Article excerpt

NEW ORLEANS -- The presence of a favorable pattern of cerebral perfusion on magnetic resonance imaging may tell physicians which patients with acute ischemic stroke stand to benefit from thrombolysis even hours after the onset of symptoms.

Findings from two phase II studies using MRI show that some patients were able to safely receive a thrombolytic drug as long as 9 hours after the onset of their stroke symptoms. Results from the most recent of these studies were reported at the 30th International Stroke Conference.

Results from the prior study, which was conducted in Europe, were published in January.

"These are the first trials to test the hypothesis that selecting patients with favorable imaging patterns can extend treatment beyond the current 3-hour window," said Anthony J. Furlan, M.D., head of the section of stroke and neurologic intensive care at the Clevel and Clinic and principal investigator of the new study.

"If this hypothesis is borne out, it could have an enormous impact on how we use thrombolytic therapy for stroke," he added. "It has the potential to at least triple the number of acute stroke patients who are eligible for thrombolytic therapy."

Like the study done in Europe, Dr. Furlan's research used a combination of perfusion-weighted and diffusion-weighted imaging by MR to identify patients with at least a 20% mismatch between the two.

The mismatch is a marker for patients with a significant penumbra region in their brain, tissue that might be salvageable by thrombolytic therapy because it is still viable despite being hypoperfused. "Most patients who made it to MR were eligible," Dr. Furlan said. "The MR criteria did not exclude a lot of patients."

The other novel feature of both the European and U.S. studies was the thrombolytic drug used; desmoteplase, a plasminogen activator derived from vampire bat saliva. Desmoteplase has several potential advantages over tissue plasminogen activator (TPA).

In animal studies, desmoteplase showed no neurotoxicity, and it did not activate [beta]-amyloid, a process that's been linked to an increased risk of intracranial hemorrhage. Desmoteplase also has very high specificity and selectivity for fibrin and a long serum half-life of 4 hours. This last property means that it can be given as a bolus dose and may also help prevent acute reocclusion of newly opened arteries.

Desmoteplase is being developed in the United States by Forest Laboratories and in Europe by PAION, a German drug company. Dr. Furlan is a consultant to both companies, and he received compensation from both for acting as a principal investigator in these and ongoing studies. …

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