This randomized controlled trial aims to evaluate whether adjunctive tirofiban therapy combined with endovascular treatment (EVT) improves neurological outcomes in patients with acute large vessel occlusion due to large-artery atherosclerosis. Patients will be randomized to receive either tirofiban or matching placebo after EVT. The primary efficacy endpoint is the proportion of patients achieving functional independence (modified Rankin Scale 0-2) at 90±7 days, while the safety endpoint is the probability of symptomatic intracranial hemorrhagewithin 48 hours after randomization.

Inclusion Criteria:

1. Age ≥18 years
2. Pre-stroke modified Rankin Scale (mRS) score of 0-1
3. Acute ischemic stroke symptoms present within 24 hours of last known well time
4. Baseline National Institutes of Health Stroke Scale (NIHSS) score ≥6
5. Anterior circulation: Alberta Stroke Program Early CT Score (ASPECTS) ≥6 Posterior circulation: pc-ASPECTS ≥6
6. Occlusion of intracranial internal carotid artery (ICA), M1 segment of middle cerebral artery (MCA), V4 segment of vertebral artery, or basilar artery
7. Clinical care team plans to perform endovascular thrombectomy (EVT)
8. Subject or legally authorized representative can provide informed consent
9. Residual stenosis ≥50% without planned angioplasty/stenting

Exclusion Criteria:

1. Intracranial hemorrhage confirmed by imaging prior to randomization, or major intracranial hemorrhage on intraprocedural flat-panel CT
2. Gastrointestinal or genitourinary bleeding within 30 days post-stroke onset, or major surgery within 14 days
3. Bleeding diathesis including coagulopathy (platelets <100×10⁹/L, aPTT >50s, or INR >2.0), DOAC use within 48 hours, or history of HIT
4. Pregnancy or lactation at admission
5. Contraindications to radiographic contrast agents, nickel, titanium or their alloys
6. Life expectancy <6 months
7. Pre-existing neurological/psychiatric conditions that may confound assessment
8. Severe renal insufficiency (GFR <30mL/min or Scr >220μmol/L [2.5mg/dL])
9. Arterial tortuosity or anomalies preventing device delivery
10. Unlikely to complete 90-day follow-up
11. Any confirmed cardioembolic source (including atrial fibrillation, valvular disease, intracardiac thrombus, recent MI, cardiomyopathy with EF <30%, etc.)
12. Tirofiban or other GP IIb/IIIa inhibitor use before randomization or other GP IIb/IIIa inhibitor used post treatment