Eptifibatide for Extended Window Ischemic Stroke After Thrombolysis

Inclusion Criteria: 1. Age ≥ 18 years. 2. Acute ischemic stroke, with the time interval from last known well to hospital presentation being 4.5 to 24 hours. 3. NIHSS score ≥ 4 before randomization; if large or medium vessel occlusion is present, an NIHSS score ≤ 10 is also required. 4. Presence of any of the following conditions after completion of standard intravenous thrombolysis: 1. No significant neurological improvement within 1 hour (defined as a change in NIHSS score ≤ 1 point from baseline). 2. Early neurological deterioration within 1 hour of onset (defined as an increase in NIHSS score ≥ 2 points from baseline). 3. Neurological fluctuation within 24 hours after symptom onset (defined as an increase in NIHSS score ≥ 2 points from the lowest value post-thrombolysis). 5. Ability to receive the assigned study drug within 60 minutes after intravenous thrombolysis. 6. Signed written informed consent obtained from the patient or their legal representative. Exclusion Criteria: 1. Intracranial hemorrhage confirmed by CT or MRI. 2. Planned endovascular therapy. 3. Presence of any definite cardioembolic source, including: chronic or paroxysmal atrial fibrillation, sick sinus syndrome, mitral stenosis, mechanical heart valve, endocarditis, intracardiac thrombus or vegetation, myocardial infarction within 3 months, dilated cardiomyopathy, spontaneous echo contrast in the left atrium, or ejection fraction \< 30%. 4. Pre-stroke modified Rankin Scale (mRS) score ≥ 2. 5. Renal insufficiency (glomerular filtration rate \< 30 ml/min or serum creatinine \> 220 μmol/L \[2.5 mg/dL\]). 6. Known hypercoagulable state. 7. Platelet count \< 100 × 10⁹/L. 8. Pregnancy or lactation. 9. Allergy to eptifibatide, other glycoprotein IIb/IIIa inhibitors, aspirin, or clopidogrel. 10. History of non-atherosclerotic arteriopathy, including moyamoya disease, arterial dissection, or fibromuscular dysplasia. 11. Pre-existing neurological or psychiatric disease that would preclude accurate neurological assessment. 12. History of bleeding diathesis, severe cardiac disease, liver disease, or sepsis. 13. Brain tumor with mass effect on imaging (except for small meningiomas). 14. Evidence of intracranial arteriovenous malformation or aneurysm with diameter \> 5 mm on CT or MR angiography. 15. Current participation in another clinical trial. 16. Any terminal illness with life expectancy \< 6 months. 17. Anticipated inability to complete follow-up.