To evaluate the efficacy and safety of endovascular therapy for posterior circulation ischemic stroke presenting more than 24 hours after symptom onset.

This study is a multicenter, open-label, blinded-endpoint, randomized controlled trial designed to evaluate the efficacy and safety of endovascular treatment administered beyond 24 hours after the onset of posterior circulation ischemic stroke. A total of 244 patients (122 per group) will be enrolled, aged ≥18 years, with a baseline NIHSS score ≥4, onset of stroke or last known well time >24 hours and within 7 days, and confirmed occlusion of the basilar artery or the intracranial segment of bilateral vertebral arteries as the culprit vessel. Patients will be randomly assigned to the experimental group (endovascular treatment plus standard medical therapy) or the control group (standard medical therapy alone). The primary endpoint is the proportion of patients with a 90-day modified Rankin Scale (mRS) score of 0-3. Secondary endpoints include the distribution of 90-day mRS scores, the proportion of patients with a 90-day mRS score of 0-2, and the 90-day EQ-5D-5L scale score. The study is led by Union Hospital, Tongji Medical College, Huazhong University of Science and Technology as the coordinating center and will be conducted at multiple centers across China, with a planned duration of 36 months.

Inclusion Criteria:

1. Age ≥ 18 years old
2. Baseline NIHSS score of 4 or higher, maintained prior to randomization
3. Stroke onset or more than 24 hours since the last known good state, but within 7 days
4. CTA/MRA/DSA confirmed occlusion of the responsible vessel in basilar artery or intracranial segments of both vertebral arteries (V4)
5. Modified Rankin Scale (mRS) score of 0 or 1 pre-stroke
6. The subject or their legally authorized representative has signed the informed consent form for the study

Exclusion Criteria:

1. Hemorrhage on CT or MRI
2. Based on the judgment of the treating physician, the patient is considered unlikely to benefit from the trial (e.g., advanced dementia, severe pre-stroke disability (mRS ≥ 2), or high risk of early mortality)
3. Major comorbidities that may interfere with outcome assessment and follow-up (e.g., severe heart failure, renal failure, etc.).
4. Evidence of vascular recanalization prior to randomization
5. Uncontrolled seizures at the time of stroke onset, if they interfere with obtaining an accurate baseline NIHSS
6. Posterior circulation Acute Stroke Prognosis Early CT score (pc-ASPECTS) < 6 on non-contrast CT or CT angiography source images or MR with diffusion-weighted imaging
7. Complete cerebellar infarct with significant mass effect and compression of the fourth ventricle,or bilateral thalamic infarction on CT or MRI
8. Baseline platelet count <50,000/uL
9. Severe, persistent hypertension (systolic blood pressure > 220 mmHg or diastolic blood pressure > 120 mmHg)
10. Known hereditary or acquired bleeding disorders, coagulation factor deficiencies, or recent oral anticoagulant therapy with an International Normalized Ratio (INR) > 3
11. Suspected purulent embolism, with a suspicion of bacterial endocarditis
12. Known allergies to iodine, heparin, anesthetics, or other explicit contraindications to the endovascular treatment procedure
13. Pregnancy
14. Other serious, progressive, or end-stage diseases (as determined by the investigator) or a life expectancy of less than 6 months
15. Attempted use of a neurothrombectomy device to remove the clot prior to randomization
16. Currently participating in a study involving other investigational drugs or devices
17. Evidence of intracranial tumor on CT or MRI (excluding meningioma)
18. CTA/MRA showing excessive tortuosity of the cervical vessels, which may interfere with endovascular treatment
19. Suspicion of aortic dissection based on medical history and CTA/MRA findings
20. Any other conditions that the investigator believes may interfere with the endovascular procedure or pose significant risk to the subject during the procedure