Abstract Body: Introduction
Current guidelines solely recommend optimal medical therapy including antiplatelet, lipid lowering, and antihypertensive treatment due to the unclear efficacy of stenting and endarterectomy for symptomatic vertebral artery (VA) stenosis. However, the incidence of recurrent ischemic stroke(RIS) in symptomatic VA steno-occlusion under optimal medical therapy in the real-world settings is not well established. This study aims to assess the incidence of RIS and identify high-risk populations who might benefit from additional interventions among patients with symptomatic VA steno-occlusion.

Methods
This retrospective study enrolled acute ischemic stroke and TIA patients from a single comprehensive stroke center between 2011 and 2022. The cumulative incidences of RIS were evaluated in patients with symptomatic VA steno-occlusion (>50% stenosis or occlusion). Outcomes were compared between patients with symptomatic VA stenosis (51-99%) and occlusion. A multivariable Cox proportional hazard model was used to assess the risk of RIS, adjusting demographics, vascular risk factors, discharge treatment, stroke severity and hyperacute treatments. Additionally, the predictors for RIS were separately analyzed in symptomatic VA stenosis and occlusion subgroups.

Results
Among 11,884 patients with acute ischemic stroke and TIA, 928 (7.8%) had symptomatic VA steno-occlusion. The mean age was 62.7 (± 14.4) years, with a male predominance (72.6%). Most patients prescribed antiplatelets (92.5%) and statins (92.8%) at discharge. EVT and angioplasty were performed in 34 (3.7%) and 29 (3.1%), respectively. The cumulative incidence of RIS in symptomatic VA steno-occlusion was 13.6% (95% CI 11.5-16.0%) at 1 year. The incidence in 517 patients with symptomatic VA stenosis (12.6% [95% CI 10.1-15.7%]) and 14.9% (95% CI 11.6-18.9%) in 386 patients with occlusion, showing similar results (Img 1). In multivariable analysis, age (HR 1.02, 95% CI 1.00-1.03, p=0.022) and endovascular treatment (EVT) (HR 2.68, 95% CI 1.36-5.28, p=0.004) increased the risk of RIS (Img 2). Age and initial NIHSS score increased the risk of RIS in symptomatic VA stenosis subgroup, while EVT increased the risk in symptomatic VA occlusion subgroup (Img 3).

Conclusion
Despite most patients with symptomatic VA steno-occlusion receiving medical treatment, the risk of RIS remains significant. Additional intervention might be considered, particularly for VA stenosis in elderly and VA occlusion in post-EVT patients.