Abstract Number: Esoc2026lb218 Impact of Nihss on Endovascular Treatment for Isolated Cervical Internal Carotid Artery Occlusion: A Secondary Analysis of the Etiica Study

Abstract Background and aims The optimal treatment strategy for patients with isolated cervical artery occlusion (i-ICA-O) remains unclear. Endovascular therapy (EVT) may be beneficial in certain subgroups – in particular in patients with severe neurological deficit. We therefore evaluated stroke severity as potential effect modifier of EVT in patients with c-ICA-O. Methods Pre-planned sub-analysis of ETIICA, a retrospective observational study conducted across 42 centers in Europe and North America, including consecutive patients with isolated c-ICA-O. The impact of the last NIHSS before treatment decision was analyzed using restricted cubic splines. We tested for interaction between NIHSS and treatment group with the 90-day mRS shift as primary outcome. Favorable outcome (mRS 0–2 or return to premorbid mRS 3) was used as secondary endpoint. Inverse probability of treatment weighting (IPTW) was combined with multivariable regression to compare EVT with best medical treatment (BMT). We further evaluated stroke severity thresholds at which EVT may be beneficial. Results Among 998 patients (mean age 71.1±13.2 years; 66.2% male), 487 (48.8%) received EVT and 511 (51.2%) BMT. No significant interaction between treatment and NIHSS was observed for mRS shift (p=0.123), but interaction was present for favorable outcome p=0.015). In patients with NIHSS 16 (EVT=182; BMT=90), EVT was associated with improved 90-day mRS (acOR 1.82, 95%CI 1.10–2.94). In this subgroup symptomatic intracranial hemorrhage occurred in 3.3% with EVT and 0% with BMT. Conclusions In patients with severe stroke due to isolated c-ICA-O, EVT may improve functional outcome. These findings may inform treatment decisions and future trial design. Conflict of interest