This is a multicenter, open, randomized controlled trial to evaluate the efficacy and safety of carotid artery stenting/carotid endarterectomy versus best medical treatment for asymptomatic carotid artery stenosis in Chinese population.

This is a multicenter, open, randomized controlled trial to evaluate the efficacy and safety of carotid artery stenting/carotid endarterectomy versus best medical treatment for asymptomatic carotid artery stenosis in Chinese population. The study will be conducted at 11 centers and is expected to enroll 1056 patients.

Inclusion Criteria:

1. Age 40-80 years;
2. Carotid artery stenosis 50%-90% (ultrasound, CT, or DSA);
3. Asymptomatic carotid stenosis, that is, no transient ischemic attack, stroke, or other neurological symptoms in the past 6 months;
4. Patients who could complete 12 months of follow-up;
5. Patients who signed informed consent forms.

Exclusion Criteria:

1. Patients who had a TIA, stroke, or other related neurological symptoms within the previous 6 months;
2. Patients with spontaneous intracerebral hemorrhage in the past 12 months；
3. Patients with large intracranial aneurysms (diameter> 5mm)，and cannot be treated in advance or contemporaneous;
4. Chronic total occlusion without obvious cerebral ischemia symptoms；
5. Patients with neurologic disorder that caused transient or permanent neurological deficits and can not be identified with transient ischemic attack or stroke；
6. Patients with severe dementia;
7. Common carotid artery opening lesion；
8. Severe intracranial stenosis in tandem;
9. Carotid artery dissection;
10. Carotid artery aneurysm;
11. Myocardial infarction occurred within 30 days；
12. It is known that two or more proximal or main coronary artery stenosis ≥70%, untreated or unable to recanalize;
13. Ejection fraction <30% or New York Heart Association (NYHA) functional class III or higher；Unstable angina，ie angina at resting state and electrocardiogram changes；
14. Patients with cardiac emboli sources, such as left ventricular aneurysm, intraluminal filling defect, cardiomyopathy, aortic or mitral prosthetic heart valve, calcific aortic stenosis, infective endocarditis, mitral stenosis, atrial septal defect, atrial septal aneurysm, or left atrial myxoma；
15. Platelet count <5×104/μL, INR>1.5, Bleeding time > 1 min, or heparin-related thrombocytopenia；Patients contraindicated to heparin and antiplatelet drugs;
16. Patients with coagulation dysfunction.
17. Poor control of diabetes, fasting blood glucose >22mmol/L and ketone body > +2；
18. Malignant tumor or respiratory insufficiency, life expectancy < 5 years.
19. Insufficiency of vital organs: forced expiratory volume at one second < 30% (predicted)； dialysis-dependent renal failure; intolerance to anesthesia;
20. Currently waiting main organ transplants (ie heart, lung, liver, kidney), or are doing relevant evaluate；
21. Need to perform other general anesthesia surgery during the same period；
22. Pregnant or lactating women；
23. Those who participated in clinical trials of other drugs or medical devices before the inclusion did not reach the end of the time limit；
24. Investigators consider the patient inappropriate to participate in this clinical trial；