Recanalization after intravenous thrombolysis: does a recanalization time window exist?

BACKGROUND: To evaluate the time course of major vessel recanalization under IV thrombolysis in relation to functional outcome in acute ischemic stroke.

METHODS: A total of 99 patients with an acute anterior circulation vessel occlusion who underwent IV thrombolysis were included. All patients had a standardized admission and follow-up procedure. Color-coded duplex sonography was performed on admission, 30 minutes after thrombolysis, and at 6 and 24 hours after onset of symptoms. Recanalization was classified as complete, partial, and absent. Functional outcome was rated with the modified Rankin Scale on day 30.

RESULTS: Complete recanalization occurred significantly more frequently in patients with multiple branch occlusions compared to those with mainstem occlusion (OR 5.33; 95% CI, 2.18 to 13.05; p < 0.0001) and was associated with lower NIH Stroke Scale (NIHSS) scores (p < 0.001). Not the specific time point of recanalization at 6 or 24 hours after stroke onset, but recanalization per se within 24 hours (OR 7.8; 95% CI 2.2 to 28.2; p = 0.002) was significantly associated with a favorable outcome. Multivariate analysis revealed recanalization at any time within 24 hours and NIHSS scores on days 1 and 7 together explaining 75% of the functional outcome variance 30 days after stroke.

CONCLUSIONS: Complete recanalization up to 24 hours after stroke onset is significantly associated with the short-term clinical course and functional outcome 30 days after acute stroke.