Stenting and Angioplasty With Protection in Patients at High Risk for Endarterectomy (SAPPHIRE)

Inclusion Criteria: 1. The patient must be \> 18 years of age. 2. The patient has a 50% stenosis (as determined by ultrasound or angiogram) of the common or internal carotid artery and is clinically symptomatic; i.e., within the previous 180 days has experienced symptoms in the ipsilateral carotid artery distribution, defined as: * one or more TIAs, characterized by distinct focal neurologic dysfunction or monocular blindness with clearing of signs and symptoms within 24 hours, or * one or more completed strokes (as defined by this protocol) with persistence of symptoms or signs for more than 24 hours (the most recent event is used as the qualifying event), except as excluded below, with stenosis \>50%, (as determined by ultrasound or angiogram) of the common or internal carotid artery, OR The patient must have a \>80% diameter stenosis (as determined by ultrasound or angiogram) of the internal or common carotid artery without neurological symptoms. 3. To be entered into the study, the patient must have one or more of the following conditions: * congestive heart failure (class III/IV) and/or known severe left ventricular dysfunction LVEF \< 30% * open heart surgery within six weeks * recent MI (\>24 hours and \<4 weeks) * unstable angina (CCS class III/IV) * synchronous severe cardiac and carotid disease requiring open heart surgery and carotid revascularization * Age greater than 80 years as a single risk factor. Exclusion Criteria: 1. The patient is experiencing an acute ischemic neurologic stroke or has experienced a stroke within the past 48 hours. 2. The patient has an intracranial mass lesion (i.e., abscess, tumor, or infection). 3. The reference segment diameter (distal common carotid and internal carotid artery segment cephalic to the lesion) is less than 4mm or greater than 9mm by quantitative analysis. See Instructions For Use, for proper stent sizing. The exception to this would be with a lesion having \>95% stenosis where the true diameter of the distal vessel can not be determined such as the case with a string sign or distal vessel collapse. In this case the judgment of the interventionalist will prevail with the intention not to oversize the stent to the distal vessel by more than 2mm. 4. The patient has known peripheral vascular, supra-aortic or internal carotid artery tortuosity which preclude the use of catheter-based techniques if so randomized. 5. The patient has any intracranial aneurysm (\> 9 mm).