Carotid angioplasty and stenting (CAS)

Ten percent of acute ischemic strokes (AIS) are due to severe carotid artery stenosis, making carotid revascularization one of the most important therapeutic managements in ischemic stroke. Older guidelines had reserved carotid artery stenting (CAS) for severe stenosis in symptomatic patients considered high risk for carotid endarterectomy (CEA). These guidelines were based on multiple previous trials including the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST) that provided evidence of the superiority of CEA as the best medical therapy for symptomatic patients. However, the recent long-term results from the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST), with over 10-years comprehensive follow-up, did not find a significant difference between patients who underwent stenting versus those who underwent endarterectomy with respect to the risk of peri-procedural stroke, myocardial infarction, or death, as well as subsequent ipsilateral stroke. Also, the rate of post-procedural ipsilateral stroke also did not differ between the two groups. This equipoise likely benefitted from increasing refinement in CAS device technology and improving techniques over the past decade. The jury is still out for asymptomatic patients, as the current evidence for this group of patients, based on Asymptomatic Carotid Atherosclerosis Study (ACAS) and the Asymptomatic Carotid Surgery Trial (ACST), is of CEA superiority in patients with more than 60% carotid stenosis, with approximately 5.5% reduction in 5-year stroke risk over CAS. The most important question about patients with asymptomatic significant carotid stenosis, recently defined as more than 70%, is whether medical treatment alone is sufficient or inferior to combined medical therapy and surgical intervention, and if inferior whether there is equipoise between CAS and CEA. This is the question that the CREST-2 study is trying to answer by 2020.