Until the irruption of the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST), carotid stenting (CAS) has been mainly offered to those patients considered at "high risk" for open carotid endarterectomy (CEA) based on the available data from large randomized clinical trials. "High risk" has been defined as (1) patients with severe comorbidity (class III/IV congestive heart failure, class III/IV angina, coronary disease involving ≥ 2 major vessels, left ventricular ejection fraction ≤ 30%, myocardial infarction, severe pulmonary disease, severe renal failure) and (2) Technical/challenging anatomical criteria (previous neck surgery, cervical irradiation, contralateral carotid occlusion, post-endarterectomy restenosis, inaccessible lesions or tracheotomy). Several recent studies have called medical "high-risk" into question for CAS indication.

The purpose of this study is to evaluate the safety and perioperative and long-term effectiveness in patients with significant carotid artery stenosis with "high-risk" criteria (for CEA) treated with carotid stenting and proximal protection device (MOMA®) compared to patients with standard-surgical-risk features.

Inclusion Criteria:

• Symptomatic patients who have a transient ischemic attack, amaurosis fugax, or minor nondisabling stroke in the distribution of the study artery within 180 days of inclusion and have been shown carotid artery stenosis ≥50% by angiography, ≥70% by ultrasound, or ≥70% by CT angiography or MR angiography if ultrasound is 50% to 69%
• Asymptomatic patients who have carotid artery stenosis of ≥60% by angiography, ≥70% by ultrasound, or ≥80% by CT angiography or MR angiography if ultrasound is 50% to 69%

Exclusion Criteria:

• Patient is unable to respond to external questions and stimuli and to exert a pressure with the contralateral hand
• Patient has an myocardial infarction within 72 hours prior to carotid stenting
• Patient has a major residual neurological deficit (stroke scales: Barthel ≤ 60, NIH ≥ 15 or Rankin >3) at pre-procedure neurological exam
• Patient had a transient ischemic attack (TIA) or amaurosis fugax within 48 hours prior to index procedure
• Patient had a stroke or retinal artery occlusion within 1 month prior to index procedure
• Patient has severe chronic renal failure (creatinine > 2.5mg/dL)
• The target carotid artery is completely occluded
• The common carotid artery ostium has stenosis that required treatment
• The presence of ipsilateral intracranial stenosis that requires treatment
• The inability to position a stiff 0.035" guidewire in the external carotid artery
• Contralateral occlusion of internal carotid artery and vertebral arteries

Internal carotid stenosis symptomatic patients who have a transient ischemic attack, amaurosis fugax, or minor nondisabling stroke in the distribution of the study artery within 180 days of inclusion and have been shown carotid artery stenosis ≥50% by angiography, ≥70% by ultrasound, or ≥70% by CT angiography or magnetic resonance (MR) angiography if ultrasound is 50% to 69%. Asymptomatic patients who have carotid artery stenosis of ≥60% by angiography, ≥70% by ultrasound, or ≥80% by CT angiography or MR angiography if ultrasound is 50% to 69%.