The goal of this clinical trial is to investigate if endovascular treatment (EVT) can effectively treat patients with large vessel occlusion (LVO) who present beyond the typical 24-hour window after symptom onset. The main questions it aims to answer are:
* Can EVT improve functional independence at 90 days for patients treated after 24 hours? * What is the safety profile of EVT in this delayed treatment group compared to best medical management (BMM)? Researchers will compare EVT outcomes in patients presenting after 24 hours to those receiving BMM to see if EVT offers significant benefits.
Participants will:
* Receive either EVT or BMM based on their eligibility. * Undergo CT angiography to assess collateral circulation and to confirm the presence of LVO. * Be followed for 90 days to evaluate functional outcomes and safety measures.
Confirmation of ICA or MCA-M1 occlusion, as detected by MRA or CTA, with carotid occlusions potentially occurring in either the cervical or intracranial regions, and the possibility of accompanying tandem MCA lesions.
Demonstration of moderate to good collateral flow, as evidenced by CTA imaging.
The patient must be aged 18 years or older.
The baseline NIHSSS score is equal to or greater than 2, and this score remains equal to or greater than 2 immediately prior to randomization.
The subject has a serious, advanced, or terminal illness (as determined by the investigator) or a life expectancy of less than six months.
The subject has a pre-existing medical, neurological, or psychiatric disease that would interfere with neurological or functional evaluations, or is already participating in another drug or device study.
The subject is pregnant.
The subject has contraindications for both MRI and CT contrast that prevent an MRI or CT contrast perfusion study. The hospital's local standard criteria should be applied to determine if contraindications exist.
Parallel
Endovascular Thrombectomy
Procedure/SurgeryEndovascular thrombectomy (EVT) in this clinical trial involves the mechanical removal of a thrombus from a blocked large cerebral artery using specialized devices like stent retrievers or aspiration catheters. Key distinguishing features of this EVT protocol include: * Extended Time Window: Unlike standard EVT, which is typically performed within 24 hours after symptom onset, this intervention targets patients presenting beyond 24 hours. * Collateral Circulation Assessment: Multi-phase CT angiography (CTA) is employed to evaluate collateral flow, prioritizing patients with favorable collateral grades. This selection process helps ensure the identification of patients most likely to benefit from EVT despite the late presentation.
modified Rankin Scale
a 7-point scale ranging from 0 (no symptoms) to 6 (death)
extended treatment in cerebral ischemia (eTICI) score
recanalization rate
score on the NIHSS
final infarct volume on MRI
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