Highest Efficacy of Dual Antiplatelet Therapy After Carotid Artery Stenting in High Bleeding Risk Patients

To compare the safety of dual antiplatelet therapy with aspirin and clopidogrel and single antiplatelet therapy administered from 30 days to 12 months following carotid artery stenting on clinically significant bleeding and its prevention effects on net clinical events including combined cardiovascular and cerebrovascular accidents and major bleeding events in patients with carotid artery disease who are at high bleeding risk.

* Arm A : Single antiplatelet therapy (SAPT) group

  - 1 month of dual antiplatelet therapy(100mg aspirin q.d. and 75mg clopidogrel q.d.) followed by 11 months of single antiplatelet therapy (100mg aspirin q.d. or 75mg clopidogrel q.d.)
* Arm B : Dual antiplatelet therapy (DAPT) with aspirin and clopidogrel - 1 month of dual antiplatelet therapy(100mg aspirin q.d. and 75mg clopidogrel q.d.) followed by 11 months of dual antiplatelet therapy (100mg aspirin q.d. and 75mg clopidogrel q.d.)

Eligibility Criteria:
Inclusion Criteria:

1. Patients ≥19 years
2. Symptomatic patients with carotid artery stenosis\* greater than 50% and asymptomatic patients with carotid artery stenosis\* greater than 70% who are scheduled to undergo or who have undergone carotid artery stenting
3. High bleeding risk is defined as a Bleeding Academic Research Consortium type 3 or 5 bleeding risk of ≥4% at 1 year or a risk of an intracranial hemorrhage (ICH) of ≥1% at 1 year, Patients who meet at least one of the criteria for high bleeding risk\*\* below

   * The degree of stenosis is determined using the method performed in the North American Symptomatic Carotid Endarterectomy Trial.

     * Criteria for high bleeding risk (≥ 1)

       * Incidence of non-access site bleeding within 12 months prior to stenting (gastrointestinal tract or hematuria)
       * Presence of BARC type 3 or 5 bleeding regardless of the onset time, but the cause has not been completely cured.
       * Adults aged ≥75 years
       * Thrombocytopenia \< 100,000/mm3 (based on the screening test)
       * Blood clotting disorders that increase bleeding (Von Willebrand disease, factor VII, VIII, IX, and XI deficiency)
       * Patients with anemia defined as hemoglobin \<12g/dL in men and \<11g/dL in women or patients who donated blood within 4 weeks (based on the screening test)
       * Patients received steroids or NSAIDs for ≥4 weeks
       * Patients with active malignancy (except for nonmelanoma skin cancer)
       * Renal disease (dialysis, transplantation, Estimated Glomerular Filtration Rate \< 60ml/min per 1.73m2)
       * Liver disease (cirrhosis with portal hypertension)
       * Cerebral microbleeds ≥ 5
       * Stroke or transient ischemic attacks within 6 months or Transient amaurosis fugax
       * Incidence of nontraumatic intracerebral hemorrhage regardless of duration or incidence of traumatic intracerebral hemorrhage within 12 months

Exclusion Criteria:

1. Incidence of net clinical events, including cardiovascular and cerebrovascular accidents or major bleeding events, within 30 days following carotid artery stenting
2. Coronary artery stenting or other vascular stenting or vascular recanalization within 1 year
3. Aspirin or clopidogrel hypersensitivity
4. Pregnant or breastfeeding women (Women of childbearing need to check for pregnancy using urine or blood tests before enrollment, and use appropriate contraception methods during the clinical trial period)
5. Patients requiring anticoagulation for ≥12 months
6. Patients requiring administration of other antiplatelet therapies
7. Patients who are participating in another intervention clinical trial