EVT in Acute Basilar Artery Occlusion With Large Infarction Core

This trial aims to evaluate whether best medical management (BMM) combined with endovascular treatment (EVT) versus BMM alone improves neurological outcomes in acute basilar artery occlusion (BAO) patients with large infarct cores. A centralized 1:1 simple randomization design assigns participants to receive either EVT or BMM based on randomization results.

• Endovascular Treatment (Procedure): The vascular access route is selected based on the patient's anatomical characteristics and operator discretion. Endovascular treatment (EVT) procedures must adhere to each participating center's standardized operating protocols. Upon confirmation of vascular occlusion, EVT may be performed using devices approved by China's National Medical Products Administration (NMPA). Based on lesion-specific features and operator judgment, permissible techniques include stent retriever thrombectomy, aspiration thrombectomy, balloon angioplasty with or without stenting, or intra-arterial thrombolysis. Investigational devices are strictly prohibited.

Primary outcomes

• Shift analysis of the improvement trend in modified Rankin Scale (mRS) scores at 90 (±7) days after randomization. [90 (±7) days after randomization]: Shift analysis is a statistical method used to evaluate the overall distribution change in modified Rankin Scale (mRS) scores, assessing whether an intervention leads to a general shift toward better outcomes across all score categories.

Secondary outcomes

• Proportion of patients with a modified Rankin Scale (mRS) score of 0-3 at 90 (±7) days after randomization. [90 (±7)days after randomization]: The modified Rankin Score is an ordinal hierarchical scale ranging from 0 to 6, with higher scores indicating more severe disability.
• Proportion of patients with a modified Rankin Scale (mRS) score of 0-2 at 90 (±7) days after randomization. [90 (±7) days after randomization]: The modified Rankin Score is an ordinal hierarchical scale ranging from 0 to 6, with higher scores indicating more severe disability.
• Change in Posterior National Institutes of Health Stroke Scale (POST-NIHSS) from baseline at 24 hours after randomization [24 hours after randomization]: The Posterior National Institutes of Health Stroke Scale (POST-NIHSS) is a tool used to assess the severity of stroke symptoms by evaluating various neurological functions, such as consciousness, vision, movement, and speech. The POST-NIHSS ranges from 0 to 52, with higher scores indicating more severe neurological deficits and a worse clinical condition.The score helps in gauging the degree of impairment caused by a stroke.
• Change in Posterior National Institutes of Health Stroke Scale (POST-NIHSS) from baseline at discharge or 7±1 days after randomization. [Discharge or 7±1 days after randomization]: The Posterior National Institutes of Health Stroke Scale (POST-NIHSS) is a tool used to assess the severity of stroke symptoms by evaluating various neurological functions, such as consciousness, vision, movement, and speech. The POST-NIHSS ranges from 0 to 52, with higher scores indicating more severe neurological deficits and a worse clinical condition.The score helps in gauging the degree of impairment caused by a stroke.
• Successful reperfusion (modified Thrombolysis in Cerebral Infarction [mTICI] score, 2b-3) [At the end of the operation]: Reperfusion was assessed using the modified Thrombolysis in Cerebral Infarction (mTICI) scale, which ranges from grade 0 (no perfusion) to grade 3 (complete reperfusion), with higher grades indicating greater reperfusion and therefore a better angiographic outcome.

Other outcomes

• All-cause mortality at 90 (±7) days after randomization. [90 (±7) days after randomization]: All-cause mortality refers to the rate of death from any cause within a specific time period, without considering the underlying cause of death.
• Incidence of symptomatic intracerebral hemorrhage (sICH) within 48 hours after randomization (Heidelberg bleeding classification). [Within 48 hours after randomization]: Intracranial hemorrhage (ICH) was assessed with the Heidelberg Bleeding Classification within 48 hours after randomization. Intracranial hemorrhage was classified as hemorrhagic infarction or parenchymal hematoma. The sICH was defined as ICH associated with a worsening of 4 or more points on the NIHSS or resulting in death and cerebral herniation, which were not present at baseline.
• Incidence of any intracerebral hemorrhage within 48 hours after randomization (Heidelberg bleeding classification). [within 48 hours after randomization]: Intracranial hemorrhage (ICH) was assessed with the Heidelberg Bleeding Classification within 48 hours after randomization. Intracranial hemorrhage was classified as hemorrhagic infarction or parenchymal hematoma.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* 1\. Age ≥18 years. 2. Symptoms and signs consistent with basilar artery ischemia. 3. Basilar artery or vertebral artery occlusion confirmed by computed tomography angiography (CTA), magnetic resonance angiography (MRA), digital subtraction angiography (DSA); if vertebral artery occlusion is present, it must completely obstruct blood flow to the basilar artery.

  4\. POST-NIHSS score ≥10 at randomization. 5. Time from symptom onset to randomization ≤24 hours (symptom onset defined as last known well time).

  6\. pc-ASPECTS of 3-5 on CT/MRI (for patients aged <80 years) or pc-ASPECTS of 3-7 (for patients aged ≥80 years).

  7\. Willingness of the patient or legally authorized representative to comply with protocol requirements and data collection procedures, with documented informed consent.

Exclusion Criteria:

* 1\. Pre-stroke modified Rankin Scale (mRS) score >2. 2. Factors in the target vessel that are expected to prevent completion of endovascular treatment.

  3\. Concurrent anterior and posterior circulation strokes or multivessel occlusions.

  4\. Significant mass effect with imaging or clinical signs of obstructive hydrocephalus or tonsillar herniation.

  5\. Basilar artery occlusion confirmed as chronic by prior imaging or investigator judgment.

  6\. Presence of untreated intracranial aneurysms, intracranial tumors (except small meningiomas), or intracranial vascular malformations.

  7\. Intracranial hemorrhage within the past 6 months, including parenchymal brain hemorrhage, intraventricular hemorrhage, or subarachnoid hemorrhage.

  8\. Presence of active bleeding, coagulation disorders, or uncorrectable bleeding tendencies.

  9\. Severe heart, liver, or kidney dysfunction or other severe systemic late-stage diseases.

  10\. Known allergy to iodine contrast agents or other treatment-related drugs. 11. Medically uncontrolled refractory hypertension (defined as persistent systolic blood pressure >185 mmHg or diastolic blood pressure >110 mmHg) (Note: Participants can be included if their blood pressure is controllable with medication and maintained at an acceptable level).

  12\. Uncontrollable blood glucose <2.8 mmol/L or >22.2 mmol/L. 13. Pregnancy or breastfeeding. 14. Life expectancy <6 months. 15. Participation in other clinical studies that may affect outcome assessment. 16. Investigator's judgment that the patient is unsuitable for participation in this study or may face significant risks (e.g., due to mental illness, cognitive, or emotional disorders preventing understanding and/or compliance with study procedures and/or follow-up).