Background: Final infarct volume after thrombolysis for acute ischemic stroke depends on time to, and degree of reperfusion and residual blood flow, which is influenced by leptomeningeal collateralization. We evaluated the role of collateralization in the ischemic territory as a predictor of infarct size. Methods: Twenty-five patients (17 women, 8 men, mean age: 67.6 ± 12.4 years) selected by non-contrast-enhanced CT and CT angiography (CTA) underwent intra-arterial thrombolysis (iaT) within 6 h after symptom onset (mean 4.1 ± 1.3 h) for middle cerebral and terminal internal carotid artery (MCA/ICA) stroke. CTA was evaluated for collateralization using thick-slice coronal and axial maximum-intensity projection reconstructions according to a simple score, the CTA collateralization score (CTA-cs): 0 = no collateral filling, 1 = ≤50%, 2 = >50% but <100%, and 3 = 100% collateral filling. We analyzed the association between the final infarct volume on CT 5 days after the intervention and the CTA-cs, successful reperfusion (Thrombolysis in Myocardial Infarction, TIMI, grades 2 and 3) and time to treatment in a prospective study approved by our institutional review board, with informed consent from all patients. Results: Reperfusion was achieved in 72%. Asymptomatic and symptomatic parenchymal hemorrhage occurred in 2 patients (8%) each and hemorrhagic transformation in 4 (16%). CTA-cs (r = –0.63; p < 0.001) and postinterventional TIMI grade (r = –0.403; p = 0.046) were inversely associated with final infarct volume. After multiple regression analysis, CTA-cs and reperfusion remained as independent predictors of final infarct volume whereas time to treatment and initial stroke severity did not. Conclusion: The extent of collateralization and reperfusion are independent predictors of final infarct volume in acute MCA/ICA stroke treated with iaT. Time to treatment and stroke severity had no independent effect on final infarct volume.

Keywords:
Collateralization, Infarct volume, Acute ischemic stroke, CT angiography
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2010
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