Thrombectomy for Mild Large Vessel Occlusion With Neurological Deterioration Beyond 24 h From Last Known Well.

RATIONALE AND OBJECTIVES: Initially mild large vessel occlusion (LVO) with neurological deterioration beyond 24 h from last known well is a challenging entity, yet the benefit of endovascular thrombectomy (EVT) in this setting remains uncertain. MATERIALS AND METHODS: We identified consecutive patients at four centers with mild LVO (National Institutes of Health Stroke Scale (NIHSS) score <6) who encountered neurological deterioration beyond 24 h from last known well. Neurological deterioration was defined as NIHSS worsening by ≥4 points overall or ≥2 points in any single item. Patients were grouped by treatment (EVT vs medical management), with inverse probability of treatment weighting (IPTW) used to balance baseline characteristics. The primary outcome was 90-day functional independence (modified Rankin Scale (mRS) score, 0-2). RESULTS: A total of 121 patients were included: 49 received EVT and 72 received medical management. After IPTW adjustment, baseline characteristics were well balanced between groups. Ninety-day functional independence was achieved in 44.6% of EVT patients versus 16.7% of patients receiving medical management (adjusted odds ratio OR 3.60, 95% confidence interval (CI) 1.62-7.99). The rate of hemorrhagic transformation (HT) was higher in the EVT group (19.6% vs 6.0%; adjusted OR 3.72, 95% CI 1.05-13.20), whereas symptomatic intracranial hemorrhage did not differ significantly between groups. Sensitivity analysis based on unweighted cohort showed that EVT was also associated with a higher likelihood of functional independence (adjusted OR 2.65, 95% CI 1.08-6.49). CONCLUSION: EVT was associated with better functional outcomes in patients with mild LVO and neurological deterioration beyond 24 h, despite an increased risk of HT.