Effect of intravenous thrombolysis in stroke depends on pattern of intracranial internal carotid artery calcification

Abstract

BACKGROUND AND AIMS: The pattern of intracranial internal carotid artery calcification (ICAC) has been identified as an effect modifier of endovascular treatment in patients with acute ischemic stroke, but it is unclear whether it modifies the effect of intravenous thrombolysis. The purpose of this study was to evaluate the association between intravenous thrombolysis and 90-day clinical outcome, follow-up infarct volume, intracranial hemorrhage and recanalization across different patterns of ICAC. METHODS: Patients with acute ischemic stroke were selected from the Dutch acute stroke study, a prospective multicenter observational cohort study. ICAC pattern was determined on admission thin-slice non-contrast CT and categorized as absent, intimal, medial or indistinguishable. The primary outcome was the ordinal 90-day modified Rankin Scale. Other outcomes included follow-up infarct volume, intracranial hemorrhage, recanalization and collateral status. Associations were quantified with regression analyses and stratified by ICAC pattern. RESULTS: Of 982 patients, 609 (62%) received intravenous thrombolysis and 381 (39%) had a 90-day modified Rankin Scale of 3-6. Intravenous thrombolysis was associated with a lower 90-day modified Rankin Scale in the group without ICAC (adjusted OR 0.3; 95%-CI 0.1-0.9) and in the group with a medial ICAC pattern (adjusted OR 0.5; 95%-CI 0.3-0.8), but not in the groups with intimal (adjusted OR 0.9; 95%-CI 0.5-1.5) or indistinguishable patterns (adjusted OR 0.6; 95%-CI 0.2-1.8). The associations between intravenous thrombolysis and follow-up infarct volume and intracranial hemorrhage were not significant for any of the ICAC pattern groups. Intravenous thrombolysis was only associated with recanalization in the group with a medial ICAC pattern (adjusted OR 3.5; 95%-CI 1.2-11.0). Compared to an intimal ICAC pattern, a medial ICAC pattern was associated with good collateral status (adjusted OR 2.6; 95%-CI 1.1-6.0). CONCLUSIONS: Intravenous thrombolysis was significantly associated with favorable clinical outcome and successful recanalization in the group with a medial ICAC pattern, but not in the group with an intimal ICAC pattern.