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Magnetic Resonance Imaging May Be Useful to Select Patients for Delayed Thrombolysis: Presented at ESC

By Michael J. Worthington

MANNHEIM-HEIDELBERG, GERMANY -- May 17, 2004 -- Thrombolysis after 3 to 6 hours of stroke onset is often considered to be too late, but it may still be effective in patients who display specific characteristics on magnetic resonance imaging (MRI), a new study finds.

Previous data concerning the efficacy of thrombolysis at delayed time points was mixed, according to Götz Thomalla, Department of Neurology, University Hospital Eppendorf, University of Hamburg, Hamburg, Germany, who reported the findings here on May 14^th[ at the 13^th[ European Stroke Conference.

The European Cooperative Acute Stroke Study II (ECASS) II, Acute Noninterventional Therapy in Ischemic Stroke (ATLANTIS) A and B revealed no effect if thrombolysis is given more than 3 hours after stroke onset. However, the Intra-arterial Prourokinase for Acute Ischemic Stroke (PROACT) II trial showed that intra-arterial thrombolysis was effective in selected patients (i.e. middle cerebral artery occlusion) if given within a 6-hour window.

The mismatch of diffusion- and perfusion-weighted (PWI/DWI) magnetic resonance imaging (MRI) is a phenomenon that shows a particular pattern. According to Dr. Thomalla, this phenomenon appears when a large penumbra exists around the lesion core, signifying an area of tissue that is poorly perfused, but still functional and salvageable.

To study outcome and bleeding complications of intravenous thrombolysis in patients with the PWI/DWI mismatch who are treated 6 hours or less after stroke onset, Dr. Thomalla and colleagues enrolled 80 patients. Forty-five patients received IV thrombolysis within 3 hours following ECASS criteria and 35 received thrombolysis within 3 to 6 hours based on MRI findings.

Results showed a favorable outcome (Modified Rankin Scale [MRS] 0-1) at day 90 in 46% of patients, moderate disability (MRS 2-3) in 28% and severe disability (MRS 4-5) in 19%. According to Dr. Thomalla, the frequency of parenchymal hemorrhage and symptomatic intracerebral hemorrhage was comparable or lower than in large thrombolysis trials. Hemorrhagic transformation was more frequent after 3-6 hours compared to 3 hours or less. The outcome appears to be comparable or better than in large thrombolysis trials (both at 3 hours or less and at 6 hours orless).

In his conclusion, Dr. Thomalla said there was no significant difference in outcomes between patients treated at 3 hours or less and those treated after 3 to 6 hours, and that MRI might be a useful tool to select patients for IV thrombolysis after 3 to 6 hours.


[Presentation title: "The Hamburg Acute MRI-guided Lysis Trial (HAMLeT): outcome and bleeding complications of thrombolysis within 6 hours in patients with PWI/DWI mismatch."]

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