Inclusion Criteria- Acute ischemic stroke
- Age ≥ 19 years old
- Modified Rankin Scale score before qualifying stroke, 0 or 1
- Baseline National Institute of Health Stroke Scale, 5 or greater
- Baseline Alberta Stroke Program Early Computed Tomographic Sign, 6 or greater
- Documented occlusion of relevant intracranial internal carotid artery or middle cerebral artery M1 segment on multiphase CT angiogram
- Starting of endovascular treatment (femoral artery puncture) should be possible between 150 minutes and 600 minutes after last seen well time.
- Nonenhanced CT and multiphase CT angiogram should be obtained in the participating hospital
- If indicated, intravenous administration of tissue plasminogen activator should be given.
Exclusion Criteria- Femoral puncture is impossible
- Pregnancy or positive on serum beta-hCG test
- Known uncontrollable allergic reaction to iodized contrast media
- Intracranial cerebral artery dissection
- Suspected chronic occlusion of the relevant intracranial large artery
- In hospital stroke
- Bilateral internal carotid artery or middle cerebral artery occlusion
- Underlying severe medical or surgical disease which may affect treatment response.
- Clinical follow is impossible because of social or medical problems.