The ENROUTE Transcarotid Neuroprotection System (ENROUTE Transcarotid NPS) DW-MRI Evaluation

The goal of this evaluation is to document the incidence of post procedure DW-MRI lesions (relative to baseline) in patients treated with the transcarotid artery revascularization (TCAR) procedure.

This is a prospective, single-arm, multi-center evaluation of patients requiring carotid revascularization who are treated with the FDA-cleared ENROUTE Transcarotid NPS in conjunction with the FDA-approved ENROUTE Transcarotid Stent System. Both the ENROUTE Transcarotid NPS and ENROUTE Transcarotid Stent System have received CE mark and are commercially available in the European Union.

Patients enrolled in this study will have been offered the TCAR intervention as part of standard of care for the treatment of carotid artery stenosis, regardless of whether or not they agree to be in the study. Therefore, the act of participation in this procedure will not be the determining factor in whether or not the patient receives the TCAR treatment. Subject participation means they agree to undergo two additional DW-MRI imaging procedures immediately after the procedure and at 30 days to determine whether there is an increase in new white lesions. Any other procedure other than the active collection of consent and data by the sponsor is standard of care for the treatment of carotid artery stenosis.

These patients will be monitored to document the incidence of post procedure DW-MRI lesions (relative to baseline).

Eligibility Criteria:
Inclusion Criteria:

* Stenosis must be \>50% as determined by ultrasound or angiogram1 and the patient has a history of stroke (minor or non-disabling; NIHSS ≤4 or mRS ≤2), TIA and/or amaurosis fugax within 180 days of the procedure ipsilateral to the carotid artery to be stented.
* Stenosis must be \>80% as determined by ultrasound or angiogram without any neurological symptoms within the prior 180 days.
* Target vessel must meet diameter requirements for stent (refer to stent IFU for diameter requirements).
* Patient has a discrete lesion located in the internal carotid artery (ICA) with or without involvement of the contiguous common carotid artery (CCA).
* Patient is willing to comply with the protocol requirements and return to the treatment center for all required clinical evaluations.
* Patient must have a life expectancy ≥ 3 years at the time of the index procedure without contingencies related to other medical, surgical or endovascular intervention.
* Patient meets at least one of the surgical high-risk criteria listed in CMS National Coverage Determination (NCD) for Percutaneous Transluminal Angioplasty (20.7)

Exclusion Criteria

* Alternative source of cerebral embolus
* Patient has chronic atrial fibrillation.
* Patient has had any episode of paroxysmal atrial fibrillation within the past 6 months, or history of paroxysmal atrial fibrillation requiring chronic anticoagulation.
* Knowledge of cardiac sources of emboli. e.g. left ventricular aneurysm, intracardiac filling defect, cardiomyopathy, aortic or mitral prosthetic heart valve, calcific aortic stenosis, endocarditis, mitral stenosis, atrial septal defect, atrial septal aneurysm, or left atrial myxoma).
* Recently (\<60 days) implanted heart valve (either surgically or endovascularly), which is a known source of emboli as confirmed on echocardiogram.
* Abnormal angiographic findings: ipsilateral intracranial or extracranial arterial stenosis (as determined by angiography or CTA/MRA ≤ 6 months prior to index procedure) greater in severity than the lesion to be treated, cerebral aneurysm \> 5 mm, AVM (arteriovenous malformation) of the cerebral vasculature, or other abnormal angiographic findings.
* Patient has a history of spontaneous intracranial hemorrhage within the past 12 months, or has had a recent (\<7 days) stroke of sufficient size (on CT or MRI) to place him or her at risk of hemorrhagic conversion during the procedure (less than one-third middle cerebral artery volume).
* Patient had hemorrhagic transformation of an ischemic stroke within the past 60 days.
* Patient with a history of major stroke attributable to either carotid artery (CVA or retinal embolus) with major neurological deficit (NIHSS ≥ 5 OR mRS ≥ 3) likely to confound study endpoints within 1 month of index procedure.
* Patient has an evolving stroke.
* Patient has an intracranial tumor.
* Patient has neurologic illnesses within the past two years characterized by fleeting or fixed neurologic deficit which cannot be distinguished from TIA or stroke, including but not limited to: moderate to severe dementia, partial or secondarily generalized seizures, complicated or classic migraine, tumor or other space-occupying brain lesions, subdural hematoma, cerebral contusion or other post-traumatic lesions, intracranial infection, demyelinating disease, or intracranial hemorrhage).
* Patient has had a TIA or amaurosis fugax within 48 hrs prior to the procedure.
* Patient has an isolated hemisphere defined as the ipsilateral middle cerebral artery being supplied only by the ipsilateral internal carotid artery.
* Patient has active bleeding diathesis or coagulopathy or will refuse blood transfusion.
* Patient had or will have CABG, endovascular stent procedure, valve intervention or vascular surgery within 30 days before or after the intervention.
* Myocardial Infarction within 72 hours prior to the intervention.
* Occlusion of the ipsilateral common or internal carotid artery.
* An intraluminal filling defect (defined as an endoluminal lucency surrounded by contrast, seen in multiple angiographic projections, in the absence of angiographic evidence of calcification) whether or not it is associated with an ulcerated target lesion.
* Patients with carotid string sign (a very high-grade carotid stenosis to the skull base with a long, thin, barely visible string of contrast within the true lumen of the artery.).
* Ostium of Common Carotid Artery (CCA) requires revascularization (\>50% stenosis).
* Patient has an open stoma in the neck.
* Patients with hostile necks due to prior neck irradiation
* Female patients who are pregnant
* Patient has history of intolerance or allergic reaction to any of the study medications or stent materials (refer to stent IFU), including aspirin (ASA), ticlopidine, clopidogrel, prasugrel, statin or contrast media (that can't be pre medicated). Patients must be able to tolerate statins and a combination of ASA and ticlopidine, ASA and clopidogrel or ASA and prasugrel.
* Patient has a life expectancy \<3 years with contingencies related to other medical, surgical, or interventional procedures as per the Wallaert Score and patients with primary, recurrent or metastatic malignancy who do not have independent assessment of life expectancy performed by the treating oncologist or an appropriate specialist other than the physician performing TCAR.
* Patient has had a recent GI bleed that would interfere with antiplatelet therapy.
* Patient is actively participating in an investigational drug or device trial (IND or IDE) that has not completed the required protocol follow-up period.
* Patient has inability to understand and cooperate with study procedures.
* Presence of extensive or diffuse atherosclerotic disease involving the proximal common carotid artery that would preclude the safe introduction of the study device.
* Patient is otherwise unsuitable for intervention in the opinion of the physician.
* Patients who cannot have MRI due to metallic implants (e.g. orthopedic implants, pacemakers, etc.)