Mechanical Thrombectomy in Basilar Artery Occlusion: Clinical Outcomes Related to Posterior Circulation Collateral Score

Abstract

Background and purpose: Basilar artery occlusion (BAO) is associated with a high risk of disability and mortality. The objective of this study was to investigate prognostic factors in patients with acute basilar artery occlusion treated with mechanical thrombectomy, focusing on collateral status and recanalization time from symptom onset.

Methods: Eligible patients from January 2012 to October 2019 who underwent endovascular treatment due to acute BAO were reviewed. The baseline posterior circulation collateral status was assessed with the basilar artery on computed tomography angiography score and posterior circulation collateral score. Good outcomes were defined as a modified Rankin Scale score of ≤2 at 3 months and successful recanalization as Thrombolysis in Cerebral Infarction grades 2b, 3. The associations between baseline and clinical parameters and favorable outcomes were evaluated with logistic regression.

Results: Our sample included a total of 81 eligible patients (49 males, mean age 70.3 years) with a median baseline and discharge National Institutes of Health Stroke Scale score of 12. Patients with good outcomes showed a lower baseline National Institutes of Health Stroke Scale score, a greater proportion of distal BAO, and a higher basilar artery on computed tomography angiography and posterior circulation collateral score (P<0.001). According to subgroup analysis of patients within and over 6 or 12 hours, the time from symptom onset to recanalization was not correlated with good outcomes. Multivariable logistic analysis showed baseline National Institutes of Health Stroke Scale <15 (odds ratio, 8.49 [95% CI, 2.01-35.82]; P=0.004), posterior circulation collateral score ≥6 (odds ratio, 3.79 [95% CI, 1.05-13.66]; P=0.042), and distal BAO (odds ratio, 3.67 [95% CI, 1.10-12.26]; P=0.035) were independent predictors of good outcomes.

Conclusions: This study suggested that good collateral circulation and distal BAO are independent predictors of clinical outcome after endovascular treatment in patients with acute BAO. In particular, patients with good initial collateral status and distal BAO may consider endovascular treatment even if the treatment is started beyond the standard time limits.

Keywords: National Institutes of Health; basilar artery; collateral circulation; computed tomography angiography; prognosis.