NASCET: Benefit of Carotid Endarterectomy in Patients with Symptomatic Moderate or S evere Stenosis

Abstract

Background Previous studies have shown that ca- rotid endarterectomy in patients with symptomatic se- vere carotid stenosis (defined as stenosis of 70 to 99 percent of the luminal diameter) is beneficial up to two years after the procedure. In this clinical trial, we as- sessed the benefit of carotid endarterectomy in pa- tients with symptomatic moderate stenosis, defined as stenosis of less than 70 percent. We also studied the durability of the benefit of endarterectomy in patients with severe stenosis over eight years of follow-up. Methods Patients who had moderate carotid ste- nosis and transient ischemic attacks or nondisabling strokes on the same side as the stenosis (ipsilateral) within 180 days before study entry were stratified ac- cording to the degree of stenosis (50 to 69 percent or <50 percent) and randomly assigned either to un- dergo carotid endarterectomy (1108 patients) or to receive medical care alone (1118 patients). The aver- age follow-up was five years, and complete data on outcome events were available for 99.7 percent of the patients. The primary outcome event was any fa- tal or nonfatal stroke ipsilateral to the stenosis for which the patient underwent randomization. Results Among patients with stenosis of 50 to 69 percent, the five-year rate of any ipsilateral stroke (failure rate) was 15.7 percent among patients treat- ed surgically and 22.2 percent among those treated medically (P=0.045); to prevent one ipsilateral stroke during the five-year period, 15 patients would have to be treated with carotid endarterectomy. Among patients with less than 50 percent stenosis, the failure rate was not significantly lower in the group treated with endarterectomy (14.9 percent) than in the med- ically treated group (18.7 percent, P=0.16). Among the patients with severe stenosis who underwent endar- terectomy, the 30-day rate of death or disabling ipsi- lateral stroke persisting at 90 days was 2.1 percent; this rate increased to only 6.7 percent at 8 years. Benefit was greatest among men, patients with recent stroke as the qualifying event, and patients with hemi- spheric symptoms. Conclusions Endarterectomy in patients with symp- tomatic moderate carotid stenosis of 50 to 69 percent yielded only a moderate reduction in the risk of stroke. Decisions about treatment for patients in this category must take into account recognized risk fac- tors, and exceptional surgical skill is obligatory if ca- rotid endarterectomy is to be performed. Patients with stenosis of less than 50 percent did not benefit from surgery. Patients with severe stenosis (70 percent) had a durable benefit from endarterectomy at eight years of follow-up.

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