Abstract WP007: Impact of Residual Stenosis Severity on Clinical Outcome after Endovascular Therapy for Acute Large Vessel Occlusion

Introduction: The relationship between residual stenosis severity after endovascular therapy (EVT) and clinical outcomes in acute intracranial atherosclerosis-related large vessel occlusion (AT-LVO) remains unclear. Hypothesis: Severe residual stenosis is associated with worse clinical outcomes after EVT for acute intracranial AT-LVO. Methods: This post-hoc analysis of the RESCUE AT-LVO multicenter historical registry included 770 patients with AT-LVO treated with EVT between January 2017 and December 2019 in Japan. Patients with intracranial AT-LVO achieving sufficient recanalization (modified Thrombolysis in Cerebral Infarction mTICI ≥2a) were categorized into three groups based on their residual stenosis severity at final postprocedural angiography: mild (<50%), moderate (50%–69%), and severe (70%–99%). The primary outcome was a composite of ischemic stroke recurrence or target lesion reocclusion within 90days. Secondary outcomes included a 90-day modified Rankin Scale score of 0–2 and mortality. Results: After excluding patients with extracranial artery lesions (n=256), insufficient recanalization (n=67), or missing stenosis data (n=5), 442 patients (mild: n=174; moderate: n=172; and severe: n=96) were analyzed. Mean age was 72 years; 70% were male; median NIHSS was 14. Baseline atherosclerotic risk factors and occlusion sites were similar across groups. Direct aspiration was more common in the severe group (44% vs. 28% in mild/moderate groups, p=0.01), while balloon angioplasty and/or stenting was more frequent in the mild group (71% vs. 58% moderate, 55% severe, p=0.01). Successful recanalization (mTICI ≥2b) was less frequent in the severe group (88% vs. 97% mild/moderate, p=0.001). The primary outcome occurred in 16% (mild), 20% (moderate), and 30% (severe). Adjusted hazard ratios (95% CI) of primary outcome of the moderate and severe groups relative to the mild group were 1.51 (0.87–2.60) and 2.52 (1.42–4.47), respectively. Secondary outcomes did not differ significantly among groups. Conclusions: Severe residual stenosis was associated with a higher risk of ischemic stroke recurrence and reocclusion after EVT for acute intracranial AT-LVO. Strategies to mitigate severe residual stenosis, including rescue angioplasty and/or stenting, may improve outcomes in this population.