Introduction The natural history of acute ischemic stroke (AIS) due to basilar artery occlusion (BAO) is poor. Endovascular reperfusion therapy (EVT) improves recanalization rates in patients with emergent large vessel intracranial occlusion.

Objective To examine the hypothesis that good collateral patterns identified by pretreatment CT angiography (CTA) might be associated with favorable outcomes after EVT.

Methods We conducted a retrospective chart review of patients presenting with AIS due to BAO in a tertiary care stroke center during a 4-year period. BAO was diagnosed by CTA in all cases. Admission stroke severity was documented using the National Institute of Health Stroke Scale (NIHSS) score. Pretreatment collateral score for posterior circulation was defined as follows: 0, no posterior communicating artery (PCOM); 1, unilateral PCOM; 2, bilateral PCOM. Favorable outcome was defined as modified Rankin Scale score of 0–2 at 3 months.

Results A total of 21 patients with AIS due to BAO (age range 31–84 years, median admission NIHSS score: 18 points, range 2–38) underwent EVT. Eleven of 21 patients (52.4%) had bilateral PCOMs, while unilateral PCOM was seen in 3 patients (14.3%). Patients with bilateral PCOMs tended (p=0.261) to have less severe stroke at admission than those with absent/unilateral PCOM (median NIHSS score 18 vs 27 points). Neurological improvement during hospitalization (quantified by the median decrease in NIHSS score) and the rate of 3-month functional independence were greater in patients with good collaterals (16 vs 0 points (p=0.016) and 72.7% vs 0% (p=0.001)).

Conclusions The presence of bilateral PCOMs on pretreatment CTA appears to be associated with more favorable outcomes in BAO treated with EVT.