Composite arterial and venous collateral score on single-phase CTA predicts 90-day outcomes in anterior circulation large-vessel occlusion stroke

BACKGROUND: Collateral circulation influences clinical outcomes in patients with acute ischemic stroke due to anterior circulation large-vessel occlusion (LVO). While both arterial and venous collateral assessments on single-phase computed tomography angiography (CTA) have prognostic value, they have traditionally been evaluated independently. PURPOSE: We developed the CTA Collateral Impairment Score (CCIS), a composite measure incorporating arterial (Tan) and venous (Cortical Venous Opacification Score (COVES)) scores, and investigated its association with 90-day functional outcomes. MATERIALS AND METHODS: We conducted a retrospective cohort study including 1080 patients with anterior circulation LVO stroke across four comprehensive stroke centers. Patients were assigned a CCIS of 0 (preserved), 1 (moderate impairment), or 2 (severe impairment) based on predefined thresholds for Tan and COVES scores. RESULTS: Favorable outcomes (modified Rankin Scale (mRS) score 0-2) occurred in 66% of patients with CCIS 0, 32% with CCIS 1, and 17% with CCIS 2 (P<0.001). Mortality increased with higher CCIS (11%, 25%, and 36% for CCIS 0, 1, and 2 respectively; P<0.001). In multivariable models, CCIS 0 and 1 were independently associated with greater odds of favorable outcomes compared with CCIS 2 (adjusted odds ratio (aOR) 5.77 (95% confidence interval (CI), 3.78 to 8.82) and 1.72 (95% CI, 1.14 to 2.60), respectively). CCIS also predicted mortality (aOR for CCIS 0 vs 2: 0.39 (95% CI, 0.25 to 0.61); P<0.001). The predictive performance of CCIS (area under the curve (AUC) 0.73) exceeded that of the Alberta Stroke Program Early CT Score (ASPECTS) and occlusion site and approximated National Institutes of Health Stroke Scale (NIHSS); inclusion of CCIS improved multivariable model discrimination (AUC 0.84). CONCLUSION: CCIS, a composite arterial and venous collateral score derived from single-phase CTA, was strongly and independently associated with 90-day outcomes in anterior circulation LVO stroke. Its integration into acute stroke imaging assessment may improve risk stratification and guide therapeutic decisions.