Large Artery Occlusion Treated in Extended Time with Mechanical Thrombectomy Trial

Inclusion Criteria:

1. Age ≥18 years

2. Present 24-72 hours of stroke onset or last seen well

3. Clinical diagnosis of AIS due to anterior circulation LVO (from internal carotidartery (ICA) extracranial segment to middle cerebral artery (MCA) M1 and M2 segment)on brain imaging

4. National Institute of Health stroke scale (NIHSS) ≥6 at randomisation

5. Viable cerebral tissue on computerized tomography perfusion (CTP) or magneticresonance imaging perfusion (MRP) assessed: infarct core volume <50mL, mismatchratio ≥1.8 and mismatch volume ≥15mL

6. Written informed consent (by patient or proxy, according to local requirements)

Exclusion Criteria:

Clinical Exclusion Criteria

1. Considered unlikely to benefit from trial (e.g. advanced dementia, major pre-strokedisability (prior modified Rankins scale (mRS) ≥2), high likelihood of early death),as judged by the responsible treating clinician

2. Major co-morbid disease that could interfere with outcome assessments and follow-up (e.g. cancer, severe heart failure, kidney failure)

3. Pregnancy

4. Unable to undergo a CTP or MRP

5. Known allergy to iodine, heparin, anaesthesia, or other definite contraindication toreceiving endovascular treatment (EVT) procedure

6. Seizures at stroke onset or before randomization and baseline NIHSS scores cannot beaccurately determined

7. Baseline blood glucose of <50mg/dL (2.78 mmol/L) or >400mg/dL (22.20 mmol/L)

8. Baseline platelet count <50,000/uL

9. Known hereditary or acquired hemorrhagic diathesis, coagulation factor deficiency;recent oral anticoagulant therapy with International normalized ratio (INR) >3

10. Severe, sustained hypertension (systolic blood pressure (BP) >220 mmHg or diastolicBP >120 mmHg)

11. Presumed septic embolus, suspicion of bacterial endocarditis

12. EVT attempted after stroke onset

13. Unlikely to participate in follow-up assessments

14. Currently participating in another trial that may affect outcomes.

15. Any other condition that, in the opinion of the investigator will pose a significanthazard to the subject if participating in the trial.

Neuroimaging Exclusion Criteria

1. Intracranial hemorrhage (ICH), including parenchymal hemorrhage, ventricularhemorrhage, subarachnoid hemorrhage, and subdural/exsanguination

2. Evidence of intracranial tumor (except small meningioma)

3. Significant mass effect with midline shift

4. Aortic dissection

5. Intracranial stent implanted in the same vascular territory

6. Any other condition that may affect EVT procedure, like the tortuous vascular paththe device is difficult to reach the target position or difficult to recover

7. Occlusions in multiple vascular territories confirmed on Computerized tomographyangiography (CTA)/ Magnetic resonance imaging angiography (MRA) (e.g. bilateral MCAocclusions, or an MCA and a basilar artery occlusion)