Please select the eligibility criteria that correspond to the clinical trial below.
Title: Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trial
Brief Summary: Carotid revascularization for primary prevention of stroke (CREST-2) is two independent multicenter, randomized controlled trials of carotid revascularization and intensive medical management versus medical management alone in patients with asymptomatic high-grade carotid stenosis. One trial will randomize patients in a 1:1 ratio to endarterectomy versus no endarterectomy and another will randomize patients in a 1:1 ratio to carotid stenting with embolic protection versus no stenting. Medical management will be uniform for all randomized treatment groups and will be centrally directed.


Options:
A: Inclusion Criteria:

1. The subject must be \> 18 and \< 80 years of age.
2. Female subjects of child bearing potential must have a documented negative pregnancy test within 30 days prior to the study procedure.
3. Subject must be asymptomatic, defined as no stroke or Transient Ischemic Attack \[(TIA);(hemispheric or ocular)\] within the 180 days prior to the procedure. Subjects who have experienced these neurological symptoms prior to the 180 day pre-procedure window will be eligible for enrollment. An independent study neurologist or independent study neurosurgeon must confirm the subject's neurological status.
4. Subjects taking warfarin may be included if their dosage is reduced before the procedure to result in an International Normalized Ratio (INR) of 1.5 or less. Warfarin may be restarted after the procedure.
5. The subject must sign a written informed consent prior to the procedure, using a form that is approved by the local institutional review board (IRB).
6. The subject must agree to return for all required follow-up visits.
7. Subject has a discrete lesion located in the internal carotid artery (ICA); the contiguous common carotid artery (CCA) may be involved.
8. Carotid stenosis ≥ 70% and ≤ 99% by carotid ultrasound or ≥ 70% and ≤ 99% stenosis (visual estimate) by angiography, without significant (\> 60% by ultrasound or angiography) ICA/CCA contralateral stenosis.
9. Target ICA vessel diameter must be visually estimated to be:

   \> 2.5 mm and \< 7.0 for the Emboshield Pro or for the Emboshield NAV6, \> 2.8 mm and \< 6.2 for the Emboshield Gen 3 And \> 4.0 mm and \< 9.0 mm for the Xact stent treatment segment. An untreated contralateral ICA may be used for visual estimation when a highly stenosed lesion makes measurement of the target vessel inaccurate.
10. Based on the subject's anatomy, the Investigator should expect to successfully deliver the stent to the target lesion (absence of extreme tortuosity, etc.).
11. De novo target lesion that can be treated with a single stent.

Exclusion Criteria:

Each potential subject must be screened to ensure that they do not meet any of the following exclusion criteria. This screening is to be based on known medical history and data available at the time of eligibility determination and enrollment.

1. Subject is symptomatic and has had a stroke or exhibited TIA (hemispheric or ocular) within 180 days prior to randomization, which has been confirmed by an independent study neurologist or independent study neurosurgeon.
2. Subject is participating in another drug or device trial (IND or IDE) that has not completed the primary endpoint or that may potentially confound the results of this trial. Subject may be enrolled only once in this trial and may not participate in any other clinical trial during a 1-year period post-index procedure.
3. Subject has inability to understand and cooperate with study procedures or provide informed consent.
4. Subject has had an intracranial hemorrhage or hemorrhagic stroke within 1-year prior the index procedure.
5. Subject has dementia or has a neurological illness that may confound the neurological evaluation.
6. Subject has had a known untoward reaction to anesthesia or contrast media not able to be overcome by pre-treatment with medications.
7. Subject has history of intolerance or allergic reaction to any of the study medications including aspirin, Clopidogrel bisulfate (Plavix®) or Ticlopidine (Ticlid®), heparin or Bivalirudin (Angiomax™). Subjects must be able to tolerate a combination of aspirin and Clopidogrel/Ticlopidine.
8. Subject has Hemoglobin (Hgb) less than 10 gm/dL, platelet count \<100,000/mm3 or \>500,000/mm3, or known heparin associated thrombocytopenia.
9. Subject has an active bleeding diathesis or coagulopathy, or will refuse blood transfusions.
10. Subject has had a GI bleed that would interfere with antiplatelet therapy.
11. Subject has known cardiac sources of emboli, including paroxysmal or sustained atrial fibrillation (treated or untreated).
12. Subject has had an myocardial infarction (MI) within the previous 30 days.
13. Subject has any condition that limits their anticipated survival to less than 3 years.
14. Subject is a high risk surgical candidate defined as the presence of any one or more of a following medical conditions:

    1. Two or more proximal diseased coronary arteries of \> 70% stenosis that have not or cannot be revascularized or \< 30 days since revascularization.
    2. Ejection fraction \< 30% or New York Heart Association (NYHA) heart failure functional class 3 or higher.
    3. Unstable angina, defined as angina at rest with ECG changes.
    4. On a list for major organ transplant or is being evaluated for such.
    5. Known history of respiratory insufficiency, forced expiratory volume (FEV1) \< 30% (predicted).
    6. Chronic renal insufficiency (serum creatinine \>2.5 mg/dL).
    7. Uncontrolled diabetes defined as fasting glucose \> 400 mg/dL.
    8. Concurrent requirement for any invasive procedure 30 days pre- or post-procedure.
    9. Age ≥ 80 years.
15. Subject may be considered a non-surgical candidate for CEA as a result of one or more anatomic conditions or features which preclude normal surgical access or a high surgical risk because of the presence of any one or more anatomic conditions that present an increased potential for adverse events. These subjects are not eligible for enrollment.

    1. Subject has had radiation treatment to the neck.
    2. Subject has had a radical neck dissection.
    3. Surgically inaccessible lesions (i.e., lesions extending above the level of C2).
    4. Spinal immobility - inability to flex neck beyond neutral or kyphotic deformity.
    5. Presence of carotid artery dissection, aneurysm, pseudoaneurysm, arteritis or fibromuscular dysplasia (FMD) in the target vessel.
    6. Hemodynamically significant (\>60%) stenosis of the right or left common carotid artery (LCCA/RCCA) below the clavicle.
    7. Presence of tracheostomy stoma.
    8. Contralateral laryngeal nerve paralysis.
    9. Previous carotid endarterectomy, extracranial-intracranial or carotid subclavian bypass procedure ipsilateral to the carotid stenosis.
    10. Severe hypertension (defined as blood pressure \> Systolic of 180 mm Hg and/or a diastolic of 110 mm Hg) not adequately controlled by anti-hypertensive therapy at the time of study entry.
16. Severe vascular disease including tortuosity and/or occlusive disease that would preclude the safe introduction of a guiding catheter/sheath, cerebral protection device, balloon catheter, stent delivery system or stent placement. Severe tortuosity is defined as 2 or more \>90 degree bend points within 3cm of the target stenosis. One of these bends will be considered to be present if the ICA branches from the CCA at a 90 degree angle. This includes aortic arch anatomy that is unacceptable for carotid stent placement.
17. Intraluminal filling defect thought to represent thrombus.
18. Excessive calcification: defined as fluoroscopic evidence of calcium that extends circumferentially around the target lesion and includes the majority of the atherosclerotic plaque.
19. Occlusion (TIMI 0 flow), or string sign of the ipsilateral common or internal carotid artery.
20. The target lesion requires treatment with a device other than percutaneous transluminal angioplasty (PTA) prior to stent placement.
21. Significant (\> 60%) stenosis proximal or distal to the target lesion that might require revascularization or impede run off.
22. Presence of a previously placed intravascular stent in the ipsilateral carotid distribution.
23. Cerebral aneurysm (symptomatic or \> 10 mm) or arteriovenous malformation (AVM) of the cerebral vasculature.
24. Bilateral carotid stenosis (ICA/CCA contralateral stenosis \> 60% by ultrasound or angiography).
B: Inclusion Criteria:

1. Patient must meet one of the following criteria regarding neurological symptom status and degree of stenosis:

   * Symptomatic: Stenosis must be greater than or equal to 50% as determined by angiogram and the patient has a history of stroke (minor or non-disabling), TIA and/or amaurosis fugax within 180 days of the procedure.
   * Asymptomatic: Stenosis must be greater than or equal to 70% as determined by angiogram without any neurological symptoms within the prior 180 days.
2. Target vessel must meet diameter requirements for stent (refer to selected stent IFU for diameter requirements).
3. Patient has a discrete lesion located in the internal carotid artery (ICA) with or without involvement of the contiguous common carotid artery (CCA).
4. Patient is greater or equal to 18 years of age.
5. Patient has no childbearing potential or has a negative pregnancy test within one week prior to the study procedure.
6. Patient understands the nature of the procedure and has provided a signed informed consent using a form that has been reviewed and approved by the Investigational Review Board/Ethics Committee of the respective clinical site prior to the procedure. This will be obtained prior to participation in the study.
7. Patient is willing to comply with the protocol requirements and return to the treatment center for all required clinical evaluations.
8. Patient meets at least one of the anatomic or clinical high-risk criteria.

Exclusion Criteria:

1. Patient has chronic atrial fibrillation.
2. Patient has had any episode of paroxysmal atrial fibrillation within the past 6 months, or history of paroxysmal atrial fibrillation requiring chronic anticoagulation.
3. Patient has an evolving stroke.
4. Patient has severe dementia.
5. Patient has a history of spontaneous intracranial hemorrhage within the past 12 months.
6. Patient 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.
7. Patient had hemorrhagic transformation of an ischemic stroke within the past 60 days.
8. Patient has active bleeding diathesis or coagulopathy or will refuse blood transfusion.
9. Patient had or will have CABG, endovascular stent procedure, valve intervention or vascular surgery within 30 days before or after the intervention.
10. Patient has had a recent GI bleed that would interfere with antiplatelet therapy.
11. Life expectancy of \< 12 months post procedure.
12. 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.
13. Myocardial Infarction within 72 hours prior to the intervention.
14. Presence of a previous placed intravascular stent in target vessel or the planned arteriotomy site.
15. Patient has had neurologic illnesses within the past two years characterized by fleeting or fixed neurologic deficit which cannot be distinguished from TIA or stroke (e.g. 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, moderate to severe dementia, or intracranial hemorrhage).
16. Patient with a history of major stroke (CVA or retinal embolus) with major neurological deficit likely to confound study endpoints within 1 month of index procedure.
17. Patient has Hgb \<10 g/dl, platelet count \<125,000/μl, uncorrected INR \>1.5, bleeding time \>1 minute beyond upper limit normal, or heparin-associated thrombocytopenia.
18. Patient has an intracranial tumor.
19. Patient is actively participating in another drug or device trial (IND or IDE) that has not completed the required protocol follow-up period.
20. Patient has inability to understand and cooperate with study procedures or provide informed consent.
21. Occlusion or \[Thrombolysis In Myocardial Infarction Trial (TIMI 0)\] "string sign" \>1cm of the ipsilateral common or internal carotid artery.
22. Patient has vertebrobasilar insufficiency symptoms only, without clearly identifiable symptoms referable to the study carotid artery.
23. 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).
24. Recently (\<60 days) implanted heart valve (either surgically or endovascularly), which is a known source of emboli as confirmed on echocardiogram.
25. Ostium of Common Carotid Artery (CCA) requires revascularization.
26. Presence of extensive or diffuse atherosclerotic disease involving the proximal common carotid artery that would preclude the safe introduction of the study device.
27. The patient has less than 5cm between the clavicle and bifurcation, as assessed by duplex Doppler ultrasound.
28. Bilateral carotid stenosis if intervention is planned within 37 days of the index procedure.
29. 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) that is not associated with an ulcerated target lesion.
30. Abnormal angiographic findings: ipsilateral intracranial or extracranial arterial stenosis 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.
31. Patient has had a previous intervention in the ipsilateral proximal CCA.
32. Patient has had a TIA or amaurosis fugax within 48 hours prior to the procedure.
33. Patient has contralateral lateral recurrent, laryngeal or vagus nerve injury.
34. Patient is otherwise unsuitable for intervention in the opinion of the investigator.
C: 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).
D: General Inclusion Criteria

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

   * Stenosis ≥70% by catheter angiography (NASCET Criteria); OR
   * by Doppler ultrasonography (DUS) with ≥70% stenosis defined by a peak systolic velocity of at least 230 cm/s plus at least one of the following:

     1. an end diastolic velocity ≥100 cm/s, or
     2. internal carotid/common carotid artery peak systolic velocity ratio ≥4.0, or
     3. computed tomography angiography (CTA) with ≥ 70% stenosis, or
     4. magnetic resonance angiography (MRA) with ≥ 70% stenosis.
3. No medical history of stroke or transient ischemic attack (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).
4. Patients must have a modified Rankin Scale (mRS) 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 carotid endarterectomy (CEA), carotid artery stenting (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/microliter 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, unless the patient has had successful atrial appendage closure (e.g., Watchman Device) and no longer requires chronic therapeutic anticoagulation.
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 patent foramen ovale (PFO) with prior paradoxical embolism.
14. Unstable angina defined as rest angina with electrocardiogram (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 forced expiratory volume (FEV1) \<30% of predicted value.
17. Known malignancy other than basal cell non-melanoma skin cancer. There are two exceptions to this rule: patients with prior cancer treatment and no recurrence for \>5 years are eligible for enrollment and 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 glomerular filtration rate (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.
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.

Specific Carotid Endarterectomy Exclusion Criteria

Patients who are being considered for revascularization by CEA must not have any of the following criteria:

1. Serious adverse reaction to anesthesia not able to be overcome by pre-medication.
2. Distal/intracranial stenosis greater than index lesion.
3. Any of the following anatomical: radical neck dissection; surgically inaccessible lesions (e.g. above cervical spine level 2 (C2)); adverse neck anatomy that limits surgical exposure (e.g. spinal immobility - inability to flex neck beyond neutral or kyphotic deformity, or short obese neck); presence of tracheostomy stoma; laryngeal nerve palsy contralateral to target vessel; or previous extracranial-intracranial or subclavian bypass procedure ipsilateral to the target vessel.

Specific Carotid Artery Stenting Exclusion Criteria

Patients who are being considered for revascularization by CAS must not have any of the following criteria:

1. Allergy to intravascular contrast dye not amenable to pre-medication.
2. Type III, aortic arch anatomy.
3. Angulation or tortuosity (≥ 90 degree) of the innominate and common carotid artery that precludes safe, expeditious sheath placement or that will transmit a severe loop to the internal carotid after sheath placement.
4. Severe angulation or tortuosity of the internal carotid artery (including calyceal origin from the carotid bifurcation) that precludes safe deployment of embolic protection device or stent. Severe tortuosity is defined as 2 or more ≥ 90 degree angles within 4 cm of the target stenosis.
5. Proximal/ostial common carotid artery (CCA), innominate stenosis or distal/intracranial stenosis greater than index lesion.

   Excessive circumferential calcification of the stenotic lesion defined as \>3mm thickness of calcification seen in orthogonal views on fluoroscopy.(Note: Anatomic considerations such as tortuosity, arch anatomy, and calcification must be evaluated even more carefully in elderly subjects (≥ 70 years).)
6. Target ICA vessel reference diameter \<4.0 mm or \>9.0 mm. Target internal carotid artery (ICA) measurements may be made from angiography of the contralateral artery. The reference diameter must be appropriate for the devices to be used.
7. Inability to deploy or utilize an FDA-approved Embolic Protection Device (EPD).
8. Non-contiguous lesions and long lesions (\>3 cm).
9. Qualitative characteristics of stenosis and stenosis-length of the carotid bifurcation (common carotid) and/or ipsilateral external carotid artery, that preclude safe sheath placement.
10. Occlusive or critical ilio-femoral disease including severe tortuosity or stenosis that necessitates additional endovascular procedures to facilitate access to the aortic arch or that prevents safe and expeditious femoral access to the aortic arch. "String sign" of the ipsilateral common or internal carotid artery.
11. Angiographic, computed tomography (CT), magnetic resonance (MR) or ultrasound evidence of severe atherosclerosis of the aortic arch or origin of the innominate or common carotid arteries that would preclude safe passage of the sheath and other endovascular devices to the target artery as needed for carotid stenting.

Answer: D