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

Prior treatment

• Prior endovascular therapy performed after the index stroke event during the current hospitalization
• Prior intracranial stent placement in the same culprit vessel
• Major surgery performed within the past 30 days

Other illness

• Pre-stroke mRS ≥ 2
• Patients with known allergies to iodine contrast agents, anesthetics, or any contraindication to endovascular treatment
• Intracranial hemorrhage identified on initial imaging
• 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
• Suspected cardioembolic stroke or stroke due to non-atherosclerotic etiologies, such as:arterial dissection,Moyamoya disease, Infective endocarditis, or Immune-mediated vasculitis

Lab values

• 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

Other

• Patients unable to undergo vascular imaging
• Significant mass effect with midline shift confirmed by CT or MRI
• 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

• 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:
  • 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;
  • 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);
  • CTP-based criteria: ischemic core volume ≤30 ml, mismatch ratio ≥ 1.8, and mismatch volume ≥ 15mL
• Signed informed consent obtained