The association between collateral status, recanalization and long term outcome in stroke patients treated with stent retrievers - Are there indications not to perform thrombectomy based on CT angiography?

Background And Purpose: To investigate the association between baseline pial collateral status on computed tomography angiography (CTA) with recanalization and functional outcome in patients with acute anterior circulation stroke treated with stent retriever thrombectomy.

Material And Methods: Retrospective analysis of 87 patients from a prospective thrombectomy registry. Collateral status on CTA source images was categorized into good, moderate, and poor with the Tan and Miteff scores by two-blinded readers. Association between CTA collateral status and successful recanalization was investigated with univariate regression analysis. Multivariate logistic regression was used to analyse the association between collateral score and favourable clinical outcome (mRS 0-2) and death at follow-up.

Results: Mean age was 72.5 years and baseline median NIHSS score was 15. Patients with poor collaterals on Tan score had a significant higher mortality compared with moderate or good collaterals during a mean follow-up period of 5.2 months (85.7% vs. 30.6% vs. 25.7%, P<0.001). Univariate logistic regression analysis did not show a significant association between Tan score (OR 1.681, 95% CI 0.683-4.140) and successful recanalization. Higher age (OR 1.067, 95% CI 1.013-1.124; P=0.015) and lower Tan score (OR 0.421, 95% CI 0.192-0.922; P=0.031) were independent predictors of death at follow-up on multivariate analysis. The Miteff collateral score could be assessed only in 65 of the 87 patients and the Tan collateral score had a higher interrater reliability.

Conclusions: Poor collaterals on CTA were associated with a very high rate of fatal outcome in anterior circulation stroke patients despite a high rate of successful recanalization with stent retrievers.