Acute ischemic stroke (AIS) is one of the leading causes of disability and mortality worldwide. The treatment of this condition is time-critical, with the key to effective therapy being the early recanalization of the occluded vessel and restoration of blood flow to salvage the ischemic penumbra tissue. Currently, the time window for endovascular treatment in the anterior circulation can be extended up to 24 hours. Exploring endovascular treatments for patients beyond this time window (from 24 hours to 30 days) could mean hope for a greater number of AIS patients.

Inclusion Criteria:

• General Inclusion Criteria

  1. Age≥18 and ≤80
  2. Baseline NIHSS ≥ 6 and maintained ≥ 6 before randomization
  3. Stroke onset or more than 24 hours from the last known well state and within 30 days.
  4. Pre-stroke mRS score of 0 or 1 points
  5. The subject or their legally authorized representative has signed the informed consent form for the study

• Imaging Inclusion Criteria

  1. Magnetic Resonance Angiography (MRA), Computed Tomography Angiography (CTA), or Digital Subtraction Angiography (DSA) confirms the occlusion of major intracranial vessels (occlusion of the internal carotid artery and/or the middle cerebral artery M1/M2 segment)
  2. Meets one of the following imaging evaluation criteria:

  1. Assessed by Computed Tomography Perfusion (CTP) or Perfusion Weighted Imaging (PWI) with MRI: Infarct core volume is less than 100 mL and the mismatch ratio is ≥1.2 or the mismatch volume is ≥10 mL.

  2. Clinical imaging mismatch is defined by MR-DWI or CTP-rCBF images as:

     1. Infarct volume is less than 30 mL and NIHSS score is ≥10;
     2. Infarct volume is between 30 mL and 100 mL and NIHSS score is ≥20

Exclusion Criteria:

• General Exclusion Criteria

  1. In the judgment of the clinician responsible for treatment, it is considered unlikely to benefit from the trial (e.g., advanced dementia, severe pre-stroke disability (mRS ≥2), high likelihood of early death)
  2. Major comorbidities that may interfere with the assessment of results and follow-up (e.g., severe heart failure, renal failure, etc.)
  3. Rapid improvement in neurologic status to NIHSS<6 or evidence of vascular reconstruction before randomization
  4. Uncontrolled seizures at the time of stroke onset that, if preventing the acquisition of an accurate baseline NIHSS
  5. Baseline platelet count<50,000/uL
  6. Severe persistent hypertension (systolic blood pressure >220 mmHg or diastolic blood pressure>120 mmHg)
  7. Known hereditary or acquired bleeding diathesis, coagulation factor deficiency, or recent oral anticoagulant therapy with an International Normalized Ratio (INR) >3
  8. Suspected septic emboli, suspected bacterial endocarditis
  9. Known allergy to iodine, heparin, anesthetics, or other clear contraindications to the endovascular treatment procedure
  10. Pregnant women
  11. Other serious, progressive, or terminal illnesses (as judged by the investigator) or life expectancy of less than 6 months
  12. Attempt to use a neurothrombectomy device to remove the blood clot before randomization
  13. Currently participating in other studies of investigational drugs or devices
  14. Any other conditions that, in the opinion of the investigator, would impede endovascular surgery or pose a significant risk to the subject during endovascular surgery

• Imaging Exclusion Criteria

  1. Intracranial hemorrhage, including parenchymal hemorrhage, ventricular hemorrhage, subarachnoid hemorrhage, and epidural/subdural hemorrhage;
  2. Evidence of intracranial tumors as shown by CT or MRI (except for small meningiomas);
  3. CTA/MRA showing excessive tortuosity of the cervical vessels, which may hinder endovascular treatment;
  4. Suspected aortic dissection based on medical history and CTA/MRA;
  5. Presence of an intracranial stent in the same vascular area, which would impede the smooth progress of surgery.