Acute basilar artery occlusion is associated with high mortality and severe disability. Previous randomized trials have demonstrated the benefit of endovascular therapy in selected patients with basilar artery occlusion; however, patients with large ischemic core, commonly defined by low posterior circulation Alberta Stroke Program Early CT Score (pc-ASPECTS), remain underrepresented and the benefit-risk profile of endovascular therapy in this subgroup is uncertain.

This prospective, multicenter, randomized, open-label, blinded-endpoint trial will evaluate the efficacy and safety of endovascular therapy plus best medical management compared with best medical management alone in patients with acute basilar artery occlusion within 24 hours from symptom onset or last known well and pc-ASPECTS <7. Eligible participants will be randomized in a 1:1 ratio to receive endovascular therapy plus best medical management or best medical management alone. The primary outcome is favorable functional outcome, defined as a modified Rankin Scale score of 0 to 3 at 90 days.

This is a prospective, multicenter, randomized, open-label, parallel-group, blinded-endpoint clinical trial. Patients aged 18 to 80 years with acute posterior circulation ischemic stroke, angiographically confirmed basilar artery occlusion, pc-ASPECTS <7 on CT/CTA source images or MRI-DWI, baseline NIHSS score ≥6, and randomization within 24 hours from symptom onset or last known well will be enrolled.

Participants will be randomly assigned in a 1:1 ratio to either endovascular therapy plus best medical management or best medical management alone. Randomization will be performed using a centralized randomization system with stratified permuted blocks. Stratification factors include study center, baseline NIHSS severity category, and onset-to-randomization time window.

Patients in both groups may receive standard intravenous thrombolysis if eligible according to current guidelines. Endovascular therapy may include stent retriever thrombectomy, direct aspiration thrombectomy, or combined techniques, at the discretion of the treating neurointerventionalist.

The primary efficacy endpoint is the proportion of patients achieving a modified Rankin Scale score of 0 to 3 at 90 days. Secondary endpoints include modified Rankin Scale score of 0 to 2 at 90 days, ordinal shift analysis of the modified Rankin Scale, changes in NIHSS and GCS scores, imaging outcomes, quality of life assessed by EQ-5D, and Barthel Index at 90 days. Safety outcomes include symptomatic intracranial hemorrhage, any intracranial hemorrhage, mortality, procedure-related complications, and serious adverse events.

Inclusion Criteria:

• Clinical symptoms or imaging findings suggestive of acute posterior circulation ischemic stroke.
• Basilar artery occlusion confirmed by CTA, MRA, or DSA.
• Posterior circulation ASPECTS <7 on CT, CTA source images, or MRI-DWI.
• Age 18 to 80 years.
• Time from symptom onset or last known well to randomization within 24 hours.
• Written informed consent obtained from the patient or legally authorized representative.
• Baseline NIHSS score ≥6 before randomization.

Exclusion Criteria:

• Pre-stroke modified Rankin Scale score ≥3.
• Pregnancy or lactation.
• Known allergy to contrast agents or nickel-titanium alloy.
• Current participation in another clinical trial.
• Systolic blood pressure >185 mmHg or diastolic blood pressure >110 mmHg that cannot be controlled with antihypertensive therapy.
• Known hereditary or acquired bleeding diathesis, coagulation factor deficiency, or current oral anticoagulant use with INR >1.7.
• Blood glucose <50 mg/dL or >400 mg/dL, platelet count <50 × 10^9/L, or hematocrit <25%.
• Life expectancy less than 1 year.
• Inability to complete 90-day follow-up.
• Definite history of cerebral vasculitis.
• Pre-existing neurological or psychiatric disorder that may interfere with neurological or functional assessment.
• Intracranial hemorrhage on CT or MRI, except for cerebral microbleeds <5 mm on MRI.
• Vascular tortuosity, anatomical variation, or arterial dissection on CTA, MRA, or DSA that precludes endovascular treatment.
• Intracranial tumor, except for small meningioma.

ndividual participant data will not be publicly shared due to restrictions related to patient privacy, ethics approval, institutional policies, and informed consent. Reasonable requests for de-identified data may be considered after publication of the primary results, subject to approval by the principal investigator and relevant ethics committees.

Due to the nature of endovascular therapy, treating physicians and participants will not be masked to treatment assignment. Outcome assessors for the 90-day modified Rankin Scale and the independent imaging core laboratory will be blinded to treatment assignment.