Who needs surveillance of the contralateral carotid artery?

BACKGROUND: Although the value of carotid endarterectomy has been proven, postoperative surveillance remains controversial. The purpose of this study was to determine the natural history of disease progression in the contralateral carotid artery by duplex surveillance, and to assess the cost of stroke prevention on this contralateral side. METHODS: Vascular laboratory records were reviewed to identify carotid endarterectomy patients who had two or more duplex studies between 1984 and 1995. Critical stenosis was defined as greater than or equal to 75% area reduction. RESULTS: In all, 324 patients were followed up with duplex scans for 1 month to 11 years (mean 30.3 months). The only factors that correlated with progression to critical stenosis were age and initial stenosis. Overall, 19.5% of patients progressed to critical stenosis within 5 years while the high-risk groups with age >65 years or initial stenosis greater than or equal to 50% progressed to critical disease in 27% and 39%, respectively (P less than or equal to 0.05). The cost per stroke prevented ranged from $143,500 to $418,200 when stratified by initial stenosis. CONCLUSION: Patients who have undergone a carotid endarterectomy demonstrate a propensity for progression of carotid stenosis in the unoperated (contralateral) artery, The cost/benefit ratio may be improved by varying the intensity of duplex surveillance of the contralateral carotid based on the patient's age and initial degree of stenosis.