CTA collateral score predicts infarct volume and clinical outcome after endovascular therapy for acute ischemic stroke: a retrospective chart review.

Background: Acute ischemic stroke (AIS) due to emergent large-vessel occlusion (ELVO) has a poor prognosis.

Objective: To examine the hypothesis that a better collateral score on pretreatment CT angiography (CTA) would correlate with a smaller final infarct volume and a more favorable clinical outcome after endovascular therapy (EVT).

Methods: A retrospective chart review of the University of Tennessee AIS database from February 2011 to February 2013 was conducted. All patients with CTA-proven LVO treated with EVT were included. Recanalization after EVT was defined by Thrombolysis in Cerebral Infarction (TICI) score ≥2. Favorable outcome was assessed as a modified Rankin Score ≤3.

Results: Fifty patients with ELVO were studied. The mean National Institutes of Health Stroke Scale score was 17 (2-27) and 38 of the patients (76%) received intravenous tissue plasminogen activator. The recanalization rate for EVT was 86.6%. Good clinical outcome was achieved in 32% of patients. Univariate predictors of good outcome included good collateral scores (CS) on presenting CTA (p=0.043) and successful recanalization (p=0.02). Multivariate analysis confirmed both good CS (p=0.024) and successful recanalization (p=0.009) as predictors of favorable outcome. Applying results of the multivariate analysis to our cohort we were able to determine the likelihood of good clinical outcome as well as predictors of smaller final infarct volume after successful recanalization.

Conclusions: Good CS predict smaller infarct volumes and better clinical outcome in patients recanalized with EVT. These data support the use of this technique in selecting patients for EVT. Poor CS should be considered as an exclusion criterion for EVT as patients with poor CS have poor clinical outcomes despite recanalization.