Commentary on: Endarterectomy for asymptomatic carotid artery stenosis. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study.. JAMA 273(18): 1421 - 1428, 1995

Keywords: carotid disease, endarterectomy, stroke, randomized trial, surgery

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     This study sought to determine if the addition of carotid endarterectomy reduced the incidence of stroke in the setting of asymptomatic carotid artery stenosis in comparison to maximal medical therapy alone.
     This study was a prospective, randomized, multicenter trial of 1662 patients with asymptomatic carotid artery stenosis of 60% or more. All patients received daily aspirin and medical risk factor management. Patients were randomized to medical treatment alone or medical treatment plus carotid endarterectomy.
     The inclusion criteria for the study were stenosis measured by (smallest lumen diameter/first point distal to numerator where walls become parallel)**same as NASCET)  of at least 60%, 40-79 years old, no history or exam consistent with a history of stroke. The exclusion criteria include cerebrovascular events in the distribution of the study artery or vertebrobasilar system, a contraindication to aspirin, a condition making surgery prohibitively dangerous or a condition likely to produce disability or death within 5 years.
     The primary end points for the study were stroke ipsilateral to the study artery or any stroke or death in the perioperative period. In the study, 146 (9%) patients did not recieve the assigned treatment. There were 10 strokes and one death (MI) in the 30 day perioperative period for the surgical group accounting for a  2.3% rate. This rate included five strokes and one death resulting from the angiogram. The perioperative stroke or death rate for the medical group was 0.4%.  For the medical group the estimated five year risk of ipsilateral stroke or perioperative stroke or death was 11%. For the surgical group the rate was 5% which resulted in a statistically significant difference. This means 19 CEAs are needed to prevent one stroke over five years. For CEA, excluding angiogram and perioperative complications, risk reduction was 79% for men and 56% for women.
     The importance of carotid artery stenosis is mentioned as accounting for 20-30% of the over 500,00 strokes per year in the United States. Asymptomatic hemodynamically significant stenosis has annual stroke rates of 2-5% and carries an unpredictable progression to occlusion. At the time of carotid occlusion disabling stroke occurs 20% of the time and thereafter carotid occlusion carries a 1.5 to 5% annual stroke risk.


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