Abstract WP22: Collateral Score and Outcome After Endovascular Treatment for Basilar Occlusion

Abstract

Introduction: Basilar artery occlusion (BAO) is a rare stroke subtype with high morbidity and mortality rates. Best reperfusion strategy is still somewhat controversial and is currently under investigation in multicenter randomized trials. We aim to describe outcomes of BAO patients submitted to mechanical thrombectomy in a comprehensive stroke center in Brazil and analyze which previous published computed tomography angiography (CTA) collateral score better predicts functional outcomes. Methods: Retrospective analysis of consecutive BAO patients from a prospective stroke registry. BAO was diagnosed through CTAs, which were also used to evaluate the Posterior Circulation Collateral Score (PC-CS), the Basilar Artery on Computed Tomography Angiography (BATMAN) scores and also for the presence of both posterior communicating arteries. A favorable outcome was defined as a mRS ≤3 at 90 days. After univariate analyses, multivariate logistic regression was used to identify if any collateral score independently predicts a favorable outcome. We also used ROC curves and C-statistics for score comparisons. Results: Between January/2011 and April/2017, 27 (85% male) BAO patients with median NIHSS of 26 (IQR:15-32) were identified. Twenty-five (93%) patients were treated with a stent-retriever or an aspiration device, and only 2 (7%) patients were treated with basilar artery angioplasty and stenting. Recanalization rate was 85% and only 1 (3.7%) patient had a symptomatic hemorrhagic transformation. Favorable outcomes were reached in 10 (37%) patients at 90-days and mortality rate was 37%. In univariate analysis, female sex, NIHSS, onset-to-groin time and PC-CS predict favorable outcomes. In multivariate analysis, only PC-CS (OR=1.69;95%CI:1.10-2.60;p=0.016) and the baseline NIHSS (OR=0.84;95%CI:0.77-0.93;p=0.001) remained as independent predictors of favorable outcomes. The PC-CS AUC for favorable outcome was 0.80 (95%CI:0.62-0.98;p=0.012). Conclusions: Mechanical thrombectomy seems to be a promising strategy for patients with acute BAO. Collateral flow assessment using the PC-CS is an independent predictor of favorable outcomes among acute BAO patients treated with mechanical thrombectomy.