A multicenter, prospective, open-label, blinded endpoint, randomized controlled trial that aims to evaluate the effect of immediate angioplasty (with or without stenting) for acute ischemic stroke (AIS) with severe intracranial atherosclerotic stenosis (ICAS) in improving the 90-day functional outcome.

This study is a multicenter, prospective, open-label, blinded endpoint, randomized controlled trial designed to evaluate the effect of immediate angioplasty (with or without stenting) for AIS with severe ICAS. The primary outcome is the proportion of patients with a 90-day modified Rankin scale (mRS) of 0-2.

Study intervention: (1) Participants in the intervention group will undergo immediate angioplasty (with or without stenting), and will receive the best medical treatment (BMT) after the procedure. (2) Participants in the control group will receive BMT alone.

This study is anticipated to enroll 412 participants.

Inclusion Criteria:

1. Aged 18 years or older.
2. Diagnosed with AIS and baseline NIHSS ≥6.
3. Pre-stroke mRS ≤2.
4. Time from symptom onset to randomization ≤ 24 hours; the onset time refers to "Last Known Well" (LKW).
5. Non-contrast CT ASPECTS score ≥6.
6. CTA confirmed severe ICAS (70-99%) of the intracranial segment of the internal carotid artery, or M1 or M2 segment of the middle cerebral artery, and is presumed to be responsible for the stroke.
7. Informed consent signed by the patient or authorized representative.

Exclusion Criteria:

1. Normal diameter of the culprit vessel <2.0 mm.
2. Isolated perforator artery infarction (except for combined cortical hypoperfusion).
3. Hemorrhagic stroke within the past 90 days.
4. Cerebrovascular conditions such as vasculitis, moya-moya disease, arterial inflammatory stenosis, vasospasm, traumatic dissection, etc..
5. Severe calcification at the stenosis site, where expected residual stenosis ≤50% cannot be achieved with procedure.
6. Known cardiac thrombus source (e.g., atrial fibrillation, patent foramen ovale, infective endocarditis).
7. INR >1.7 when using warfarin; coagulation dysfunction or uncorrectable bleeding factors.
8. Platelet count <50×10^9/L.
9. Intracranial hemorrhage confirmed by CT or MRI.
10. Women who are pregnant or breastfeeding.
11. Participation in other intervention clinical trials.
12. Known severe renal insufficiency with glomerular filtration rate <30 ml/min or blood creatinine >220 μmol/L (2.5 mg/dl).
13. Severe allergy to contrast (non-mild rash allergy) or absolute contraindication to iodine contrast.
14. Aortic dissection.
15. Concomitant intracranial tumor (except for meningioma <10mm) or arteriovenous malformation.
16. Severe vascular tortuosity, difficult access for intervention, or inability to complete endovascular treatment.
17. Any active bleeding or recent bleeding in the last 1 month.
18. SBP>185 mmHg or DBP>110 mmHg refractory to treatment.
19. Anticipated life expectancy <3 months (e.g., malignancy, severe cardiopulmonary disease, etc.).
20. Any condition that, in the judgment of the investigator, makes the patient unsuitable for this study or where this study may impose a significant risk to the patient (e.g., inability to understand and/or comply with study procedures and/or follow-up due to psychiatric disorders, cognitive or emotional impairment).

The IPD will be available from Principal Investigators (Prof. Yamei Tang and Prof. Yajie Liu) upon reasonable request 6 months after the trial completion.

6 months after the trial completion.

The IPD will be available from Principal Investigators (Prof. Yamei Tang and Prof. Yajie Liu) upon reasonable request.