ABSTRACT NUMBER: ESOC2026A1118 RISK FACTORS FOR INTRACRANIAL HEMORRHAGE AFTER NON-ACUTE ENDOVASCULAR THERAPY OF SYMPTOMATIC MIDDLE CEREBRAL ARTERY STENOSIS

Abstract Background and aims Symptomatic middle cerebral artery stenosis (sMCAS) accounts for 40%-70% of intracranial atherosclerotic stenosis in Asians. While non-acute endovascular therapy (EVT) improves stenosis, postprocedural symptomatic intracranial hemorrhage (sICH) adversely affects outcomes. This study aimed to investigate sICH-associated risk factors following non-acute EVT in sMCAS patients. Methods We retrospectively analyzed 241 sMCAS patients undergoing EVT (2020-2024) included clinical characteristics, perioperative management, angiographic characteristics, and EVT strategies. Secondary collaterals were assessed via ASITN/SIR scale, tertiary collaterals via Matsushima grade and Baltsavias G’s method. SICH was confirmed via cranial computed tomography (CT) findings and clinical manifestations. Results 235 patients were finally analyzed (6 excluded for procedural failure or poor imaging), with 20 developing sICH. SICH patients had similar baselines to non-sICH patients (all P > 0.05), but showed higher critical stenosis (≥ 90%) prevalence (P = 0.008), inadequate secondary collaterals (P = 0.028), and more frequent tertiary collaterals formation (Matsushima, P = 0.011; Baltsavias G.’s method, P = 0.006). Multivariate regression identified inadequate secondary collaterals as an independent predictor of sICH (OR = 3.108, 95% CI: 1.067-9.047, P = 0.038). Conclusions Critical stenosis, inadequate secondary collaterals, and tertiary collaterals formation were linked to post-EVT sICH in sMCAS patients, with inadequate secondary collaterals as an independent risk factor. Conflict of interest Weidong Ling1, Yun Luo, Yun Xu，Xin Zhang, Qing Ye.nothing to disclose