Abstract Number: Esoc2026ot47 Clinical Outcomes After Extracranial-Intracranial Bypass in Occlusive Cerebrovascular Disease: Study Protocol for a Prospective Single-Arm Interventional Cohort Study

Abstract Background and aims Occlusive cerebrovascular disease is a major cause of ischemic stroke, and patients with large-vessel disease remain at high risk of recurrence despite available medical therapy, with reported recurrence rates of 12-14%. Extracranial-intracranial (E-IC) bypass is a preventive strategy in selected patients with hemodynamic compromise. However, changes in superficial temporal artery diameter after bypass and their relationships with postoperative cerebral perfusion and neurocognitive outcomes have not been systematically studied. Methods To evaluate vascular-morphological, perfusional, and cognitive changes following superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass in patients with chronic internal carotid artery (ICA) occlusion and documented cerebral hypoperfusion. Results Patients with asymptomatic or symptomatic ICA occlusion undergoing STA-MCA bypass (N=60) will be prospectively enrolled between August 2025 and December 2027. Time-to-event outcomes (recurrent stroke/TIA) will be analyzed using Kaplan-Meier methods, with exploratory Cox regression to evaluate associations with baseline covariates (e.g., age, sex, vascular risk factors, baseline perfusion). Multivariable linear or logistic regression will be used to explore predictors of perfusion or cognitive improvement and perioperative events, with effect estimates reported with 95% confidence intervals and two-sided p-values (α=0.05). Conclusions Primary outcomes include bypass patency, cerebral perfusion improvement, and perioperative ischemic events (stroke or TIA within 30 days). Patency will be assessed by postoperative vascular imaging, and perfusion changes will be quantified using Arterial Spin Labeling-MRI or CT perfusion. Secondary outcomes include recurrent stroke or TIA, neurological status, and neuropsychological performance, assessed at baseline, 6 months, and during follow-up. Conflict of interest