Abstract TP310: Collateral Status and Infarct Volume as Determinants of 90-Day Disability After Large-Core Thrombectomy

Background: Endovascular Thrombectomy (EVT) improves outcomes in patients with large core acute ischemic stroke, but identifying patients who benefit remains a challenge. Here, we study whether pre-procedure CTA collateral scoring successfully classifies treatment benefit. Methods: We analyzed consecutive patients from the prospectively collected, multi-center PRIME registry cohort (11 certified stroke centers, January 2018-March 2024) with anterior circulation large vessel occlusion acute ischemic stroke and large core (ASPECT score 0-5) who underwent EVT. Collateral status was assessed on baseline single-phase CTA maximum intensity projection images using the Tan system (0-3). Final infarct volumes were measured on MRI performed 48-72 hours after reperfusion. Predictors of 90-day functional independence (mRS 0-2 vs 3-6) were evaluated using multivariable logistic regression, adjusting for collateral score, age, sex, baseline NIHSS, time from symptom onset to hospital arrival, and final infarct volume. Results: A total of 114 patients were included (mean age 64.7 years; 50% male), with a mean final infarct volume of 115.6 mL using the ABC/2 method. Collateral scores were 0 in 20 patients (18.5%), 1 in 50 (46.3%), 2 in 28 (25.9%), and 3 in 10 (9.3%). At 90 days, functional independence (mRS 0-2) was achieved in 19 patients (16.7%), with rates rising in step with better collateral status (score 0: 5%, score 1: 22%, score 2: 14.3%, score 3: 30%). On multivariable logistic regression (mRS 0-2 vs 3-6), adjusting for age, sex, baseline NIHSS, time from onset, and infarct volume, collateral score was not significantly associated with functional independence (OR 1.23, 95% CI 0.60–2.59, p = 0.57). Larger infarct volume remained independently associated with lower odds of functional independence (OR 0.985 per mL, 95% CI 0.974–0.995, p = 0.009), while age showed a trend toward worse outcome (OR 0.958 per year, 95% CI 0.913–1.002, p = 0.068). NIHSS and time from onset were not significantly associated with the 90-day outcome. Conclusion: In large-core anterior circulation strokes treated with EVT, a large infarct volume independently predicts lower odds of 90-day functional independence, while collateral score, NIHSS, and time from onset were not significant predictors. A larger cohort may help better evaluate the prognostic value of baseline collateral status.