Background: For moderate to severe carotid artery atherosclerotic stenosis, in the past decades, carotid artery stenting (CAS) has been an alternative to carotid endarterectomy (CEA) for the treatment of carotid artery stenosis. The transfemoral artery (TFA) using Seldinger's technique has been the most commonly used approach for CAS. The radial artery is an ideal puncture site for cerebrovascular intervention. Studies have shown that nerve intervention through radial artery approach can complete most cerebrovascular intervention procedures, including cerebral angiography, carotid artery stent implantation, vertebral artery stent implantation, intracranial artery stent implantation, mechanical thrombectomy, aspiration, intra-arterial thrombolysis and so on. However, the current studies are based on single center small sample studies, and there has been still a lack of large sample randomized controlled experiments to verify the safety and effectiveness of CAS in transradial artery (TRA) .

Objective: To evaluate the efficacy and safety of CAS via TRA in patients with carotid artery stenosis through a multicenter, prospective and randomized study.

Study design: This study is a randomized, open label, multicenter, parallel controlled trial. A non-inferiority test is performed to compare the primary end point between the experimental group and the control group. The experimental group will undergo carotid stent implantation via radial artery approach, while the control group will use femoral artery approach.

Study population: Adult patients with symptomatic carotid-artery stenosis ≥50% or asymptomatic stenosis ≥70%.

Study outcomes: Primary end points: The incidence of death, or new-onset stroke, or myocardial infarction, or severe hemorrhage events within 30 days post-procedure Secondary end points:1.The incidence of death, or new-onset stroke, or myocardial infarction, or severe hemorrhage events within 48 hours post-procedure. 2. The incidence of death, new-onset stroke and myocardial infarction within 48 hours / 30 days post-procedure. 3. The incidence of death within 48 hours / 30 days post-procedure. 4. The incidence of new-onset stroke within 48 hours / 30 days post-procedure. 5. The incidence of myocardial infarction within 48 hours / 30 days post-procedure. 6. The incidence of severe hemorrhage events within 48 hours / 30 days post-procedure. Other end points: 1. Successful rate of cerebral angiography. 2. Successful rate of CAS. 3. Degree of patient-reported comfort. 4. Operation time. 5. NIHSS score changes within 5-7 days post-procedure. 6. mRS score score within 30 days post-procedure. Safety outcomes: 1.Occurrence of all adverse events. 2. AEs related to operation and device. 3. Incidence of adverse event of special interest.

Inclusion Criteria:

• General inclusion criteria

  1) Age≥18 years old

• Clinical inclusion criteria

  1. Symptomatic stenosis: patients had a transient ischemic attack (TIA), amaurosis, or minor nondisabling stroke involving the target carotid artery within 180 days before randomization.
  2. Asymptomatic stenosis: The results of medical history, physical examination and neurological examination do not suggest ischemic symptoms in the target carotid artery. If artery stenosis degree reache the standard, but there are any one or more of the following symptoms including: non-carotid artery symptoms; contralateral carotid artery symptoms; time from symptom to randomization more than 180 days; and vertebrobasilar artery symptoms. In these situations, patients are considered to be asymptomatic.
  3. Pulsation is palpable in the radial and femoral arteries, and the radial artery must meet any of the following criteria: Allen test or Barbeau test suggesting that ulnar artery collateral circulation is good, or preoperative ultrasound confirming that the radial artery and ulnar artery are well developed.
  4. No family planning within half one year after informed consent signed, or negative pregnancy test for women with childbearing potential.
  5. Patients or their guardians can understand the study purpose, voluntarily participate in the trial, sign informed consent, and complete follow-up visits.

• Vascular inclusion criteria

  1. Lesions located in the internal carotid artery, with or without involvement of the adjacent common carotid artery (CCA).
  2. For symptomatic patients, at least one of the following conditions should be met: stenosis of 70% or more on ultrasonography; 70% or more on computed tomographic angiography (CTA) or magnetic resonance angiography (MRA); 50% or more on digital subtraction angiography (DSA) according to NASCET standard.
  3. For asymptomatic patients, at least one of the following conditions should be met: stenosis of 70% or more on ultrasonography; 80% or more on CTA or MRA; 60% or more on DSA according to NASCET standard.
  4. When bilateral carotid stenosis presented, only unilateral carotid artery can be treated. The other carotid artery, as a non-study artery, should be dealt with 30 days before randomization or 30 days after treatment.
  5. According to clinician experience, the operation access would be reasonable and the surgical instruments could be successfully delivered to the lesion site.

Exclusion Criteria:

• General exclusion criteria

  1. Progressive stroke.
  2. Allergic to drugs associated with carotid artery stenting, such as lidocaine, aspirin, clopidogrel, etc.
  3. Allergic to contrast media or interventional device.
  4. Any active hemorrhage, severe anemia, coagulation disorders, or unnecessary blood transfusion treatment. Meet at least one of the following laboratory tests: hemoglobin < 10g/dL, or platelet count < 100000 /μ L, or unadjusted INR >1.5, or PT beyond upper limit of normal for 1 minute, or heparin-induced thrombocytopenia.
  5. Previous ipsilateral large cerebral infarction stroke with sequelae, which can affect the judgment of the study end point.
  6. Severe cognitive disorder, unable to cooperate with treatment or postoperative evaluation.
  7. Spontaneous intracranial hemorrhage occurred 12 months prior to informed consent written. Ischemic stroke hemorrhage transformation occurred 3 months prior to informed consent signed.
  8. A new-onset stroke occurred 7 days prior to informed consent signed, which has a high hemorrhagic transformation risk after preoperative imaging evaluation.
  9. Any condition that could interfere with digital subtraction angiography (DSA) or make percutaneous arterial access unsafe.
  10. Neurological disorders occurred 2 years prior to informed consent signed, which has transient or fixed neurological deficits, cannot be distinguished from TIA or stroke.
  11. Participating in other clinical trials, in the research phase or follow-up phase.
  12. Unable to understand or sign the informed consent.
  13. Myocardial infarction within 30 days.
  14. High surgical risk, intolerance to interventional surgery, e.g., coronary artery stenosis ≥70% without or unable to revascularization; ejection fraction < 30% or NYHA classification ≥class III; stable angina pectoris (static angina pectoris with ECG changes); organ transplantation (such as heart, lung, liver and kidney) planned or under evaluation; malignant tumour or respiratory insufficiency making life expectancy less than 5 years or FEV1< 30%(prediction); dialysis-dependent renal failure; poorly controlled diabetes mellitus(fast serum glucose >400 mg/dl and urine ketone > +2).
  15. Diseases or anatomical features that would prevent from carotid artery stenting, such as pathway problems caused by cervical radiation therapy, and cervical space occupying lesion compressing carotid artery

• Vascular exclusion criteria

  1. Severe vascular tortuosity or dissection that influence catheters delivering
  2. Stenting, balloon dilation or coiling were performed in ipsilateral vessels in the past.
  3. Extensive or diffuse atherosclerotic disease involving the aortic arch and the proximal common carotid artery, which would influence catheters delivering
  4. Besides the target vessel, there are also ipsilateral intracranial or extracranial arteries stenosis larger than the target lesion, aneurysms with the longest diameter ≥5 mm, cerebrovascular AVM(arteriovenous malformation), or other cerebrovascular disease with abnormal cerebral angiography.
  5. Ipsilateral carotid artery chronic occlusions.
  6. Plan to perform endovascular tretment of other arteries at the same time, including vertebral arteries.