A New Angiographic Collateral Grading System for Acute Basilar Artery Occlusion Treated with Endovascular Therapy.

Poor clinical outcomes despite endovascular therapy (EVT) are common in patients with acute basilar artery occlusion (BAO). We aimed to develop a new angiographic collateral grading system for predicting 90-day functional outcomes of acute BAO after EVT. A prospectively registered consecutive cohort of acute BAO patients treated with EVT in our center during a 6-year period was reviewed. The angiographic collateral grading system for BAO (ACGS-BAO) included 4 grades for poor (grade 1-2), intermediate (grade 3), and good (grade 4) collateral statuses. First, the independent association of ACGS-BAO with 90-day functional independence (mRS ≤ 2), favorable outcome (mRS ≤ 3), and death was evaluated by multivariable logistic regression model; then, the heterogeneity in the effects of ACGS-BAO on 90-day outcomes was explored among the subgroups stratified by age, time window, stroke severity, and etiology. Finally, the interobserver agreement of ACGS-BAO was assessed by weighted kappa statistic. Of 173 patients included in this study, 62 (35.8%), 83 (48.0%), and 36 (20.8%) achieved 90-day functional independence, favorable outcome, and death, respectively. Multivariable logistic analyses showed that ACGS-BAO was independently associated with functional independence (OR = 2.07, 95% CI = 1.05-4.07) and favorable outcome (OR = 1.84, 95% CI = 1.02-3.43) but not related to death (OR = 0.78, 95% CI = 0.37-1.64). Similar effects of ACGS-BAO on 90-day outcomes were seen across all subgroups (P > 0.10 for all interactions). The interobserver agreement of ACGS-BAO was very high (weighted kappa = 0.96, 95% CI = 0.93-0.99). The ACGS-BAO is an angiographic tool with excellent interobserver reliability that can be used to predict the 90-day outcome of acute BAO treated by EVT. Nevertheless, our findings are still needed to be confirmed in a prospective multicenter study before clinical application.