- Significant artery stenosis in symptomatic patients defined as ≥ 50% of the artery diameter (%DS) or asymptomatic ≥ 80 %DS by angiography. Symptomatic is defined as a carotid artery stenosis associated with ipsilateral transient ischemic attack (TIA), amaurosis fugax, ischemic stroke or retinal infarction within 6 months prior to enrollment.