Endovascular Treatment for Acute Large Vessel Occlusion With Ultra-Large Ischemic Core

The primary objective is to determine whether EVT combined with BMM, compared with BMMalone, improves functional outcome in patients with intracranial LVO in anteriorcirculation and ultra large‐core treated within 24 hours of symptom onset.Primary Efficacy Endpoint Analysis The primary efficacy endpoint is the mRS score at 90days after randomization. The proportional odds assumption will be formally assessed. Ifthis assumption holds (score test p‐value > 0.05), the primary effect measure is thecommon odds ratio (cOR), which will be estimated using an ordinal logistic regressionmodel to assess the shift in the overall distribution of the mRS scale at 90 days. Themodel will be adjusted for known prognostic factors including baseline ASPECTS score,age, NIHSS score at admission, and intravenous thrombolysis, as well as the randomizationstratification factor, i.e., time from stroke onset or last known well to randomization(≤6 hours vs. >6 hours). Unadjusted cOR estimates and confidence intervals (CI) will alsobe reported. If the assumption is violated, the generalized odds ratio (GenOR) and its95% CI will be derived as a robust alternative measure of treatment effect.Secondary Efficacy Endpoints Analysis For the secondary endpoint of mRS score at 180 daysafter randomization, the same analysis method as for the primary endpoint will be used.For the proportions of mRS 0‐2 and mRS 0‐3 at 90 days and 180 days, early neurologicalimprovement, a modified Poisson regression model will be used, reporting Risk Ratio and95% CI, with the same adjustment factors as in the primary endpoint analysis. For thecomparison of EQ‐5D‐5L score at 90 days between two arms, a linear regression model willbe used to estimate the mean difference and 95% CI. For the change in infarct volume frombaseline assessed by NCCT at 7 (±1) days or discharge (whichever occurs earlier), or byMRI at 36 (±12) hours after randomization, a linear regression model will be used toestimate the mean difference and 95% CI, with treatment group as the study variable andbaseline measurement as a covariate; if normality assumptions are violated, the win ratiomethod will be used.Safety Analysis For the primary safety endpoint of all‐cause mortality within 90 daysafter randomization, the Chi‐squared test or Fisher's exact test will be used forbetween‐group comparison. For the secondary safety endpoints, including incidence of sICHwithin 24 hours from onset, proportion of early neurological deterioration, procedure‐ ordevice‐related complications, and serious adverse events adjudicated by the ClinicalEvents Committee, data summary will be performed by treatment group.