Inclusion Criteria:

• Eligibility for the parent CREST-2 trial included male and female individuals who are ≥ 35 years old and who have high-grade asymptomatic stenosis involving the cervical internal carotid artery.
• A patient is considered asymptomatic in the absence of ipsilateral symptoms < 180 days prior to randomization.
• Carotid stenosis is defined as high-grade if catheter angiography documents ≥ 70% stenosis per criteria used in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) or duplex ultrasonography (DU) documents peak systolic velocity (PSV) of ≥ 230 cm/s in combination with at least one of the following four criteria: end diastolic velocity of ≥ 100 cm/s, internal carotid artery-to-common carotid artery PSV ratio ≥ 4.0, computed tomography angiogram (CTA) showing ≥ 70% stenosis, or a magnetic resonance angiogram (MRA) showing ≥ 70% stenosis.
• All currently active patients in the CREST-2 trial will be eligible for C2LOE. 
• Most CREST-2 participants are Anglophone; however, there are also a small number of native French speakers (largely in Quebec, Canada) and native Spanish speakers (largely in Florida, Texas, and California sites, as well as the Barcelona, Spain center).
• The Survey Research Unit (SRU) conducting the interviews can perform assessments in both French and Spanish, allowing inclusion of these patients in the long-term follow-up.

Exclusion Criteria:

• Inability to secure written informed consent to be followed in this protocol.