Abstract WP258: Predicting Stroke Outcomes Using Cerebrovascular Collateral Circulation in Patients with Large Ischemic Core

Introduction: Endovascular Thrombectomy (EVT) is highly effective for the treatment of acute ischemic stroke (AIS), but patients with large core infarcts (LC-AIS), defined by low ASPECTS or large infarct volume, were initially excluded from EVT trials. Emerging evidence suggests that select LC-AIS patients may benefit from EVT. Collateral circulation robustness is a key factor in preserving brain perfusion and limiting infarct growth. We hypothesize that collateral status significantly influences outcomes in LC-AIS patients undergoing EVT. Methods: We retrospectively analyzed LC-AIS patients who underwent EVT between 2019 and 2024, using a prospectively collected database at our comprehensive stroke center. Quantitative collateral index (qCI) was calculated from the initial computed tomography angiography (CTA) using our validated and fully automated machine-learning algorithm. The primary outcome was hospital disposition. Results: Patients with ASPECTS <6 were included in the analysis. Those who achieved a favorable outcome, defined as discharge to home, were significantly younger (mean age 56 vs. 72 years, p=0.0010) and had lower admission NIHSS scores (mean 10 vs. 19, p=0.0001) compared to those discharged to rehabilitation, nursing care, hospice, or deceased. There were no statistically significant differences between groups in terms of sex, race, core infarct volume, penumbra volume, time from symptom onset to recanalization, and rate of successful recanalization (TICI ≥2B). The qCI was significantly higher in patients without good outcomes versus those with poor outcomes (p=0.028) Multivariate logistic regression analysis identified younger age (OR = 1.04; 95% CI: 1.003–1.098; p = 0.0383), lower NIHSS score at admission (OR = 1.19; 95% CI: 1.06–1.34, p = 0.0003) and qCI (OR = 1.8, 95% CI:0.93-3.60, p value = 0.08) as independent predictors of favorable discharge disposition. Conclusion: Among LC-AIS patients, younger age, lower NIHSS at presentation and quantitative assessment of collateral circulation were associated with favorable discharge disposition. These findings demonstrate the potential to enhance stroke prognosis and guide personalized therapeutic interventions by incorporating patient-specific quantitative cerebrovascular metrics to identify at LC-AIS patients at risk of worse outcomes.