CAROTID REVASCULARIZATION AND MEDICAL MANAGEMENT FOR ASYMPTOMATIC CAROTID STENOSIS TRIAL (CREST-2) PROTOCOL

General Inclusion Criteria:

1. Patients ≥35 years old.
2. Carotid stenosis defined as:

• Stenosis ≥70% by catheter angiography (NASCET Criteria); OR
• by DUS with ≥70% stenosis defined by a peak systolic velocity of at least 230 cm/s plus at least one of the following:
• an end diastolic velocity ≥100 cm/s, or
• internal carotid/common carotid artery peak systolic velocity ratio ≥4.0, or
• CTA with ≥ 70% stenosis, or
• MRA with ≥ 70% stenosis

3. No medical history of stroke or TIA ipsilateral to the stenosis within 180 days of randomization. Life-long asymptomatic patients will be defined as having no medical history of stroke or transient ischemic attack and negative responses to all of the symptom items on the Questionnaire for Verifying Stroke-free Status (QVSS).18
4. Patients must have a modified Rankin Scale score of 0 or 1 at the time of informed consent.
5. Women must not be of childbearing potential or, if of childbearing potential, have a negative pregnancy test prior to randomization.
6. Patients must agree to comply with all protocol-specified follow-up appointments.
7. Patients must sign a consent form that has been approved by the local governing Institutional Review Board (IRB)/Medical Ethics Committee (MEC) of the respective clinical site.
8. Randomization to treatment group will apply to only one carotid artery for patients with bilateral carotid stenosis. Management of the non-randomized stenosis may be done in accordance with local PI recommendation. Treatment of the non-study internal carotid artery must take place at least 30 days prior to randomization, or greater than 44 days after randomization and 30 days after the study procedure is completed (whichever is longer).
9. Carotid stenosis must be treatable with CEA, CAS, or either procedure.

**General

Exclusion Criteria:**

1. Intolerance or allergic reaction to a study medication without a suitable management alternative.
2. GI hemorrhage within 1 month prior to enrollment that would preclude antiplatelet therapy.
3. Prior major ipsilateral stroke in the past with substantial residual disability (mRS ≥ 2) that is likely to confound study outcomes.
4. Severe dementia.
5. History of major symptomatic intracranial hemorrhage within 12 months that was not related to anticoagulation.
6. Prior Intracranial hemorrhage that the investigator believes represents a contraindication to the perioperative or periprocedural antithrombotic and antiplatelet treatments necessary to complete endarterectomy or stenting per protocol.
7. Current neurologic illness characterized by fleeting or fixed neurologic deficits that cannot be distinguished from TIA or stroke.
8. Patient objects to future blood transfusions.
9. Platelet count <100,000/μl or history of heparin-induced thrombocytopenia.
10. Anticoagulation with Phenprocoumon (Marcumar®), warfarin, or a direct thrombin inhibitor, or anti-Xa agents.
11. Chronic atrial fibrillation.
12. Any episode of atrial fibrillation within the past 6 months or history of paroxysmal atrial fibrillation that is deemed to require chronic anticoagulation.
13. Other high-risk cardiac sources of emboli, including left ventricular aneurysm, severe cardiomyopathy, aortic or mitral mechanical heart valve, severe calcific aortic stenosis (valve area < 1.0 cm2), endocarditis, moderate to severe mitral stenosis, left atrial thrombus, or any intracardiac mass, or known unrepaired PFO with prior paradoxical embolism.
14. Unstable angina defined as rest angina with ECG changes that is not amenable to revascularization (patients should undergo planned coronary revascularization at least 30 days before randomization).
15. Left Ventricular Ejection fraction <30% or admission for heart failure in prior 6 months.
16. Respiratory insufficiency with life expectancy < 4 years or FEV1 <30% of predicted value.
17. Known malignancy other than basal cell non-melanoma skin cancer. There are two exceptions to this rule: 1) patients with prior cancer treatment and no recurrence for >5 years are eligible for enrollment; or 2) cancer patients with life expectancy of greater than 5 years are eligible for enrollment.
18. Any major surgery, major trauma, revascularization procedure, or acute coronary syndrome within the past 1 month.
19. Either the serum creatinine is ≥ 2.5 mg/dl or the estimated GFR is < 30 cc/min.
20. Major (non-carotid) surgery/procedures planned within 3 months after enrollment.
21. Currently listed or being evaluated for major organ transplantation (i.e. heart, lung, liver, kidney).
22. Actively participating in another drug or aortic arch or cerebrovascular device trial for which participation in CREST-2 would be compromised with regard to follow-up assessment of outcomes or continuation in CREST-2.
23. Inability to understand and cooperate with study procedures or provide informed consent.
24. Non-atherosclerotic carotid stenosis (dissection, fibromuscular dysplasia, or stenosis following radiation therapy).
25. Previous ipsilateral CEA or CAS.
26. Ipsilateral internal or common carotid artery occlusion.
27. Intra-carotid floating thrombus.
28. Ipsilateral intracranial aneurysm > 5 mm not successfully treated with clipping, coiling, or flow diversion.
29. Extreme morbid obesity that would compromise patient safety during the procedure or would compromise patient safety during the periprocedural period.
30. Coronary artery disease with two or more proximal or major diseased coronary arteries with ≥ 70% stenosis that have not, or cannot, be revascularized.