Abstract Body: Background: Intracranial Atherosclerosis carries a high recurrence rate. Single center studies have shown that impaired distal perfusion is a driver of early recurrence. In this study, we aim to identify predictors of 30-day ischemic stroke recurrence in a multicenter cohort.

Methods: This is a pooled analysis of individual patient data from four comprehensive stroke centers of hospitalized patients with symptomatic intracranial arterial stenosis (50-99%) of the intracranial ICA and proximal middle cerebral artery (M1 or proximal M2). The study outcome was recurrent ischemic stroke by day 30. We compared baseline demographics (age, sex, race, ethnicity), vascular risk factors (hypertension, hyperlipidemia, diabetes, atrial fibrillation), NIHSS score, last known well to arrival, home medications (aspirin, anticoagulation), imaging variables (prior infarct in territory, degree of stenosis, perfusion delay volume, borderzone infarct pattern), and in-hospital treatments (thrombolysis, dual antiplatelet therapy, statin, permissive hypertension). Variables with p<0.1 on univariate analyses were included in a Cox regression model to identify important outcome predictors. Missing data was imputed as absent for categorical variables and at the median for continuous variables.

Results: We identified 274 patients hospitalized with symptomatic intracranial stenosis who met the inclusion criteria; 70 patients (25.5%) had a recurrent ischemic stroke within 30 days. In unadjusted Cox regression models, predictors of early recurrence were mismatch volume of 25 ml or greater at T max of 6 seconds (HR 2.19 95% CI 1.37-3.51, p = 0.001), 70-99% (vs. 50-69%) stenosis (HR 3.34 95% CI 1.05-10.60, p = 0.041), diabetes (HR 1.60 95% CI 1.0-2.57, p = 0.048), home aspirin (HR 1.77, 95% CI 1.06-2.95, p = 0.029), and home statin (HR 1.73 95% CI 1.04-2.89, p = 0.039). In adjusted Cox regression, the only predictors of 30-day recurrence were T max 6 mismatch volume 25 mL or more (adjusted HR 2.14 95% CI 1.27-3.61, p = 0.004), and 70-99% (vs. 50-69%) stenosis (adjusted HR 3.37 95% CI 1.05-10.84, p = 0.041).

Conclusions: One in four medically treated patients with proximal anterior circulation symptomatic ICAS have a recurrent stroke within 30 days with impaired distal perfusion being an important driver of recurrence. Studies are needed to validate these findings and test reperfusion strategies in those with impaired perfusion.