Basilar Artery Occlusion Chinese Endovascular Trial

Inclusion Criteria: 1. Posterior circulation AIS within 6-24 hours from symptom onset/last seen well where patient is ineligible for i.v. thrombolytic treatment, or patient has received i.v. thrombolytic therapy without recanalization. 2. Occlusion (Thrombolysis in Myocardial Infarction, TIMI 0-1) of the basilar artery or intracranial segments of both vertebral arteries as evidenced by computed tomography (CT) angiography, magnetic resonance (MR) angiography or angiogram. 3. Age ≥18 and ≤80 years. 4. Baseline National Institutes of Health Stroke Scale (NIHSS) score obtained prior to randomization must be equal to or higher than 6 points. 5. No significant pre-stroke functional disability (modified Rankin Scale, mRS ≤ 1). 6. Patient treatable within 24 hours from time last seen well. Isolated vertigo with nausea and/or vomiting is not considered onset of symptom. 7. Informed consent obtained from patient or acceptable patient surrogate. Exclusion criteria General Exclusion Criteria: 1. Known hemorrhagic diathesis, coagulation factor deficiency, or oral anticoagulant therapy with international normalized ratio \> 3.0. 2. Baseline platelet count \< 50.000/µL. 3. Baseline blood glucose \< 50mg/dL or \> 400mg/dL. 4. Severe, sustained hypertension (systolic blood pressure \> 220 mm Hg or diastolic blood pressure \> 110 mm Hg). 5. Patients in sedation and/or intubated patients could not be included if baseline NIHSS is not obtained by a neurologist or emergency physician prior to sedation or intubation. 6. Seizures at stroke onset which would preclude obtaining a baseline NIHSS. 7. Serious, advanced, or terminal illness with anticipated life expectancy of less than one year. 8. History of life threatening allergy (more than rash) to contrast medium 9. Subjects who has received i.v. tissue plasminogen activator (t-PA) treatment beyond 4.5 hours from the beginning of the symptoms. 10. Patients with acute stroke within the first 48 hours after percutaneous cardiac, cerebrovascular interventions and major surgery (beyond 48h they should be randomized in BAOCHE or excluded for endovascular treatment if poor medical conditions). 11. Renal insufficiency with creatinine ≥ 3 mg/dl. 12. Woman of childbearing potential who is known to be pregnant or lactating or who has a positive pregnancy test on admission. 13. Subject participating in a study involving an investigational drug or device that would impact this study. 14. Cerebral vasculitis. 15. Patients with a pre-existing neurological or psychiatric disease that would confound the neurological or functional evaluations; mRS score at baseline must be ≤ 1. 16. Unlikely to be available for 90 days follow-up. Neuroimaging Exclusion Criteria: 1. Hypodensity amounting to a posterior circulation Acute Stroke Prognosis Early CT score (pc-ASPECTS) \< 6 and Pons-midbrain-index of ≥ 3 on CT angiography source images or MR with diffusion-weighted imaging or NCCT. 2. CT or MR evidence of hemorrhage (the presence of microbleeds on MRI is allowed). 3. Complete cerebellar infarct on CT or MRI with significant mass effect and compression of the fourth ventricle. 4. Complete unilateral or bilateral thalamic infarction on CT or MRI 5. Evidence of vertebral occlusion, high grade stenosis or arterial dissection in the extracranial or intracranial segment that cannot be treated or will prevent access to the intracranial clot or excessive tortuosity of cervical vessels precluding device delivery/deployment. 6. Subjects with occlusions in both anterior and posterior circulation. 7. Evidence of intracranial tumor (except small meningioma).