Effect of Balloon Angioplasty vs Stenting Following Residual Stenosis After Endovascular Treatment of Intracranial Atherosclerotic Acute Ischemic Stroke

Inclusion Criteria: 1. Age 18 years or older. 2. Pre-stroke modified Rankin Scale (mRS) score of 0-1. 3. Symptoms of acute ischemic stroke presenting within 24 hours of the last known well time. 4. Baseline National Institutes of Health Stroke Scale (NIHSS) score of at least 6. 5. Baseline Alberta Stroke Program Early CT Score (ASPECTS) of at least 6 for anterior-circulation stroke, or posterior-circulation ASPECTS (pc-ASPECTS) of at least 6 for posterior-circulation stroke. 6. Occlusion of the intracranial internal carotid artery, M1 segment of the middle cerebral artery, V4 segment of the vertebral artery, or basilar artery. 7. The clinical care team plans to perform endovascular treatment. 8. The participant or the participant's legally authorized representative is able to provide written informed consent. 9. Baseline CT perfusion or MR perfusion imaging demonstrating an ischemic core volume of less than 70 mL, a mismatch ratio of at least 1.2, and a mismatch volume of at least 15 mL. 10. Intracranial atherosclerosis is considered the underlying etiology, with residual stenosis of at least 50% after endovascular treatment, and rescue balloon angioplasty or stenting is planned Exclusion Criteria: 1. Any intracranial hemorrhage identified on imaging before randomization; or major intracranial hemorrhage, defined as parenchymal hematoma type 1 or type 2, identified on intraprocedural flat-panel CT. Parenchymal hematoma type 1 is defined as blood clots involving less than 30% of the infarcted area, with or without a slight space-occupying effect; parenchymal hematoma type 2 is defined as blood clots involving more than 30% of the infarcted area with a substantial space-occupying effect. 2. Gastrointestinal or genitourinary bleeding within 30 days before stroke onset, or major surgery within 14 days before stroke onset. 3. Bleeding diathesis, including platelet count below 100 × 10⁹/L, activated partial thromboplastin time greater than 50 seconds, or international normalized ratio greater than 2.0; treatment with a direct oral anticoagulant within the preceding 48 hours; or a history of heparin-induced thrombocytopenia. 4. Pregnancy or breastfeeding at admission. 5. Contraindication to iodinated contrast agents, nickel, titanium, or their alloys. 6. Life expectancy of less than 6 months. 7. Pre-existing neurological or psychiatric disease that may confound neurological or functional outcome assessment. 8. Severe renal impairment, defined as glomerular filtration rate below 30 mL/min or serum creatinine above 220 μmol/L (2.5 mg/dL). 9. Arterial tortuosity or another arterial condition that would prevent the study device from reaching the target vessel. 10. Unlikely to complete the 90-day follow-up. 11. Any definite cardioembolic source, including chronic or paroxysmal atrial fibrillation, sick sinus syndrome, mitral stenosis, mechanical heart valve, endocarditis, history of atrial or ventricular thrombus, myocardial infarction within the preceding 3 months, dilated cardiomyopathy, spontaneous echo contrast in the left atrium, or left ventricular ejection fraction below 30%. 12. Use of any glycoprotein IIb/IIIa inhibitor other than tirofiban.