Abstract 233: Collateral Status and Outcomes in ICAS‐LVO: Insights From the RESCUE‐ICAS Registry

Introduction The influence of collateral circulation on outcomes in intracranial atherosclerotic stenosis‐related large vessel occlusion (ICAS‐LVO) treated with mechanical thrombectomy (MT) with or without rescue stenting is not well defined. We aimed to determine whether collateral status modifies the effect of stenting on angiographic and clinical outcomes. Methods We analyzed patients with ICAS‐LVO in the RESCUE‐ICAS registry who underwent MT alone or with rescue stenting in the anterior circulation. Collaterals were graded as good or bad based on ASITN/SIR score. Outcomes included functional independence (mRS 0‐2 at 90 days), mortality, successful recanalization, sICH, and 24‐hour DWI infarct volume. Regression models evaluated stenting and collateral status interaction, adjusted using inverse probability weighting for age, sex, race, diabetes, hypertension, atrial fibrillation, hyperlipidemia, prior stroke, smoking, pre‐stroke mRS, admission NIHSS, IV tPA, and baseline ASPECTS, with weights trimmed at ≤4. Results A total of 324 patients were included (MT alone, n=182; stent+MT, n=142). Median age was 67 years, 57% were male, and vascular comorbidities were frequent. Good collaterals were present in 27% of cases. Interaction analysis between stenting and collateral status showed no significant effect modification for functional independence (adjusted OR 0.78, 95% CI 0.33‐1.82, p =0.560), mortality (adjusted OR 1.56, 95% CI 0.52‐4.68, p =0.425), sICH (adjusted OR 0.22, 95% CI 0.04‐1.42, p =0.112), or infarct volume (β = ‐10.1 mL, 95% CI ‐32.9 to 12.7, p =0.656). A borderline interaction was observed for successful recanalization, with stenting in the setting of good collaterals associated with higher odds of reperfusion (adjusted OR 5.34, 95% CI 0.90‐31.7, p =0.065). Conclusions In patients with anterior circulation ICAS‐LVO, collateral status did not significantly modify the benefit of rescue stenting. These findings suggest that good collaterals alone do not obviate the need for stenting, and highlight the need for prospective studies to define optimal medical management strategies in this population. image image