Abstract WMP17: Time to Treatment, Collaterals and Recanalization in Basilar Artery Occlusion: Which Factors Determine Prognosis?

Abstract

Background: Whether radiological factors influence the effect of time to recanalization on outcome in basilar artery occlusion (BAO) is uncertain. We evaluated the association between onset time to treatment (OTT), radiological prognostic factors (presence of collaterals and extent of the occlusion) and clinical outcome in endovascular BAO patients. Methods: Clinical and radiological data of consecutive endovascular-treated stroke patients with BAO diagnosed on CT angiography at Royal Melbourne Hospital (Australia), Royal Adelaide Hospital (Australia), University Hospital of Tor Vergata (Rome, Italy) and from the international BASICS registry were retrospectively analysed. The Basilar Artery on Computed Tomography Angiography (BATMAN) score and Posterior Circulation Collateral Score (PC-CS) were assessed by two investigators blinded to clinical outcome. Previously validated dichotomies for favorable BATMAN score (≥7) or PC-CS (≥6) were used. Good outcome was defined as modified Rankin Scale≤3 within 3 months; successful reperfusion as mTICI 2b-3 (or TIMI 2-3 in BASICS). Results: We included 155 BAO patients treated with intra-arterial urokinase and/or mechanical thrombectomy (86 with mechanical thrombectomy): mean(SD) age 65(14), median NIHSS 22 (IQR 12-30), median OTT 348.5 min [(IQR 246-480), 37% treated beyond 6hours]. In logistic regression adjusted for age and NIHSS, OTT>6h was associated with poor outcome (OR 3.0, 95%CI 1.4-6.6, p=0.006) but this association was only present in the subgroup with unfavourable BATMAN score (adjusted OR 4.6, 95%CI 1.7-12, p=0.002) or PC-CS (3.7, 95%CI 1.3-11, p=0.02) and not in those with favorable BATMAN score (adjusted OR 0.7, 95%CI 0.2-3.6, p=0.7) or PC-CS (2.7, 95%CI 0.6-12, p=0.2). When successful reperfusion was added to the model with age and NIHSS, OTT>6h remained significantly associated with poor outcome in patients with unfavorable BATMAN score (OR 5.0, 95%CI 1.8-14, p=0.002) or PC-CS (4.5, 95%CI 1.4-14, p=0.01), but not in patients with favorable BATMAN score (OR 1.6, 95%CI 0.2-13, p=0.6) or PC-CS (3.2, 95%CI 0.6-17, p=0.2). Conclusions: BAO patients with good collaterals and less extensive occlusion may have good outcome if recanalization is achieved even in a delayed time window.