Efficacy and Safety Study of Endovascular Treatment of Asymptomatic Carotid Artery Stenosis

Inclusion Criteria: 1. Age 40-80 years 2. Severe asymptomatic internal carotid artery stenosis (70-99%) confirmed by ultrasound/CTA/DSA 3. Contralateral ICA stenosis \<70% 4. No TIA/stroke related to target lesion in past 6 months 5. Declined carotid endarterectomy 6. Willing to complete 12-month follow-up 7. Signed informed consent by participant/legal representative Exclusion Criteria: 1. symptomatic internal carotid artery stenosis in the past 6 months 2. Spontaneous intracranial hemorrhage in nearly one year 3. Patients with larger intracranial aneurysms (diameter \>5 mm) who cannot undergo prior or concurrent treatment 4. Chronic occlusion without obvious symptoms of cerebral ischemic attack 5. Patients with transient or permanent neurological deficit resulting from Neurological deficits mimicking TIA/stroke from TIA or stroke 6. Common carotid artery ostial lesion 7. Tandem lesions with severe stenosis of the ipsilateral intracranial artery 8. Patients with severe dementia 9. Internal carotid artery dissection 10. Internal carotid artery aneurysm 11. Myocardial infarction within 30 days 12. Ejection fraction \<30% or New York Heart Association (NYHA) functional class III or higher; unstable angina, characterized by angina at rest with electrocardiogram changes 13. Cardiogenic embolism, including left ventricular aneurysm, intraluminal filling defects, cardiomyopathy, aortic or mitral valve-prosthetic heart valve, calcified aortic stenosis, infective endocarditis 14. Mitral stenosis, atrial septal defect, atrial septal aneurysm or left chamber myxoma 15. Two or more proximal or main coronary artery stenosis 70%, untreated or recanable 16. Platelets \<5 \* 104 / uL, INR\> 1.5, bleeding time\> 1min or heparin-related thrombocytopenia; heparin is a contraindication to antiplatelet drugs; coagulopathy 17. Poor controlled diabetes mellitus, fasting blood glucose\> 22 mmol/L and ketone body\>+2 18. Malignant tumor or respiratory insufficiency, and a life expectancy of \<5 years 19. Severe liver and kidney function impairment, ALT\> 3 times the upper limit of normal value or AST\> 3 times the upper limit of normal value, blood creatinine increase\> 2 times the upper limit of normal value 20. Contrast allergy 21. Other general anesthesia operations are required during the same period 22. Pregnant or lactating women 23. The patient does not attend the clinical trial of other drug or medical device before enrollment 24. The investigator is not considered fit to participate in this clinical study Imaging exclusion criteria: 1. Type III aortic arch 2. Severe angulation or tortuosity (≥90 degrees) of the common carotid artery or innominate artery that prevents safe and rapid placement of a guiding catheter or long sheath 3. Severe angulation or tortuosity of the internal carotid artery that prevents safe deployment of an embolic protection device or stent. Severe tortuosity is defined as the presence of two or more angles ≥90 degrees within 4 cm of the stenotic lesion 4. Stenosis of the beginning or proximal end of the common carotid artery, innominate artery, distal or intracranial segment of the internal carotid artery, and the stenosis degree is greater than that of the target stenosis 5. The stenotic lesion exhibits severe circumferential calcification, defined as calcification greater than 3 mm in thickness visible in orthogonal views during fluoroscopy. (Note: In elderly subjects aged ≥70 years, anatomical factors such as tortuosity, arch anatomy, and calcification must be assessed more carefully)