- Subjects are included if they have a COICA with ischemic symptoms refractory to medical therapy. Symptoms are evaluated based on the North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria. Carotid occlusion is defined as 100% cross-sectional stenosis of the vessel lumen as documented on CT angiography or magnetic resonance angiography and confirmed with diagnostic angiogram (DSA).