PREVALENCE OF ASYMPTOMATIC CAROTID STENOSIS IN PATIENTS UNDERGOING INFRAINGUINAL BYPASS-SURGERY

Background: The prevalence of asymptomatic carotid stenosis in patient s with lower-extremity ischemia is unknown. This report represents the largest carotid screening program to date of patients undergoing leg bypass. Design: Patients undergoing infrainguinal bypass from 1987 thr ough 1993 on the vascular surgery service at Oregon Health Sciences Un iversity, Portland, underwent routine carotid duplex examinations to d etect the presence of asymptomatic carotid stenosis. Patients: During the study period, 352 patients underwent infrainguinal revascularizati on for ischemia, of whom 225 (64%) had no prior carotid surgery, carot id arteriography, or cerebrovascular symptoms. There were 117 men and 108 women, with a mean age of 67 years. The indication for surgery was limb salvage in 67% and claudication in 33% of patients. Results: Six ty-four patients (28.4%) who required lower-extremity revascularizatio n had hemodynamically significant asymptomatic carotid artery stenosis or occlusion; 12.4% had stenosis of 60% or greater, the qualifying le vel for randomization in the Asymptomatic Carotid Atherosclerosis Stud y. Based on these findings, eight patients with carotid stenosis of 80 % or greater underwent elective carotid endarterectomy. There were no postoperative neurologic events in the 225 leg bypass patients. By mul tivariate logistic regression analysis, the presence of carotid bruit (P<.001) and the presence of rest pain (P=.006) were associated with c arotid stenosis of 50% or greater. Limiting screening to patients with carotid bruit, limb salvage indications for surgery, and/or advanced age excluded significant numbers of patients with stenosis; thus, thes e were not effective screening strategies. Conclusion: Screening carot id duplex scanning is indicated in patients who require lower-extremit y revascularization.