- Prior imaging study (CTA or ultrasound) showing ≥ 50% stenosis of a supra-aortic vessel segment (within 60 days before consent). The proportion of subjects with positive disease (determined by the investigator, based on CTA or ultrasound) will be monitored during the study, and enrolment may be further restricted to require ≥ 70% stenosis to ensure that overall there are an adequate number of subjects with clinically significant disease for the evaluation of study endpoints.