Thrombolysis Window May Be Longer Than Thought

Patients with proximal arterial occlusion more likely to have lengthy diffusion-perfusion mismatch
By Jane Parry
HealthDay Reporter

THURSDAY, Feb. 12 (HealthDay News) -- Patients with acute stroke may have a diffusion-perfusion mismatch after nine hours of stroke onset, particularly those with proximal arterial occlusion, suggesting the treatment window for stroke may be extended in some cases, according to the results of a study published in the March issue of Radiology.

William A. Copen, M.D., of Massachusetts General Hospital and Harvard Medical School in Boston, and colleagues conducted a study of 109 patients who underwent diffusion-weighted and perfusion-weighted MRI within 24 hours of the onset of a stroke. There were 68 patients with proximal arterial occlusion and 41 without, and the patients were all assessed as to their eligibility for hypothetical thrombolysis.

There were 77 patients (71 percent of the total) who met the Desmoteplase in Acute Ischemic Stroke Trial and Dose Escalation of Desmoteplase for Acute Ischemic Stroke Trial criteria for thrombolysis eligibility, and 61 (56 percent) of the patients were eligible on the basis of 160 percent mismatch between the two imaging tests, the researchers report. Among patients with no proximal arterial occlusion, eligibility was less after nine hours. Patients with proximal arterial occlusion became increasingly eligible for thrombolysis with no significant difference seen for after nine hours versus before nine hours, the investigators found.

"Our findings expand on those of prior studies by showing that the existence of the mismatch after more than nine hours is dependent on the existence of a proximal arterial occlusion," the authors write.

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