Endovascular Treatment Beyond 24 Hours for Acute Ischemic Stroke Caused by Anterior Circulation Large Vessel Stenosis

Inclusion criteria: * Age \> 18 years * Acute ischemic stroke with a time window of 24 to 120 hours from symptom onset or last known well, or progressive ischemic stroke with a time from symptom onset of 24 hours to 7 days (A ≥4-point increase in NIHSS attributable to the culprit vessel territory ) * NIHSS score 5-25 * Occlusion or ≥70% stenosis of the internal carotid artery or the M1/M2 segment of the middle cerebral artery, confirmed by CTA, MRA, or DSA, and deemed to be the culprit vessel responsible for the clinical presentation of acute ischemic stroke * Meet one of the following imaging criteria: 1. MRI-based criteria: the infarct volume on DWI is less than one-third of the MCA territory, with evidence of DWI-FLAIR mismatch or MR perfusion showing a core infarct volume ≤30 ml, a mismatch ratio ≥1.8, and a mismatch volume ≥15 ml; 2. CTA-based criteria: good collateral circulation on the affected side defined ascollateral filling \>50% of the MCA territory (Tan score ≥2) and an ASPECTS score ≥6); 3. CTP-based criteria: ischemic core volume ≤30 ml, mismatch ratio ≥ 1.8, and mismatch volume ≥ 15mL * Signed informed consent obtained Exclusion criteria: * Pre-stroke mRS ≥ 2 * Patients unable to undergo vascular imaging * Patients with known allergies to iodine contrast agents, anesthetics, or any contraindication to endovascular treatment * Prior endovascular therapy performed after the index stroke event during the current hospitalization * Intracranial hemorrhage identified on initial imaging * Platelet count \<50×10⁹/L, or presence of a known hemorrhagic diathesis , coagulation factor deficiencies, or use of oral anticoagulation therapy with an International Normalized Ratio (INR) \> 3.0 * Refractory hypertension, defined as sustained systolic blood pressure \>200 mmHg or diastolic blood pressure \>120 mmHg despite optimal medical management * History of intracranial hemorrhage within the past 3 months, including parenchymal hemorrhage, intraventricular hemorrhage, subarachnoid hemorrhage, epidural hemorrhage, or subdural hemorrhage * Significant mass effect with midline shift confirmed by CT or MRI * Suspected cardioembolic stroke or stroke due to non-atherosclerotic etiologies, such as:arterial dissection,Moyamoya disease, Infective endocarditis, or Immune-mediated vasculitis * Prior intracranial stent placement in the same culprit vessel * Major surgery performed within the past 30 days * Pregnant or current breastfeeding * Presence of severe systemic comorbidities with a life expectancy of less than 3 months * Deemed unsuitable for participation by the investigator for any reason