Objective: Although the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the Asymptomatic Carotid Atherosclerosis Study (ACAS) have helped to define the role of carotid endarterectomy (CEA) for both symptomatic and asymptomatic lesions, the role of surveillance of the contralateral carotid artery remains unclear. The purpose of this study was to determine the progression of contralateral carotid artery disease with serial duplex ultrasound scans after CEA compared with the recurrent stenosis rate for the carotid artery ipsilateral to the CEA.
Methods: From January 1990 to December 2000, 473 CEA procedures were performed at a Veterans Affairs Medical Center. From this group we identified 279 patients who had undergone first-time CEA, as well as preoperative duplex scanning and postoperative duplex scanning at least once, in the vascular laboratory. At each visit stenosis of the internal carotid artery (ICA) was categorized as none (0%-14%), mild (15%-49%), moderate (50%-79%), severe (80%-99%), or occluded. Analysis of probability of freedom from progression was determined. Progression was defined as an increase in ICA stenosis 50% or greater or increase to a higher category of stenosis if baseline was 50% or greater. The Cox proportional hazards model was used for data analysis.
Results: Mean patient age was 65.7 years (range, 33-100 years). The 1024 carotid duplex ultrasound scanning examinations performed (mean, 3.7; range, 2-13) included the last study done before the index CEA and all studies done after the CEA. Mean follow-up was 27 months (range, 1-137 months). Forty-six patients were found to have contralateral carotid occlusion at initial duplex scanning, and were therefore excluded from the contralateral progression analysis. Contralateral progression was more frequent than ipsilateral recurrent stenosis at long-term follow-up (P <.01). Annual rates of "any progression" and "progression to severe stenosis or occlusion" were 8.3% and 4.4%, respectively, for contralateral arteries, and 4.3% and 2.4%, respectively for ipsilateral arteries. As a result of surveillance, 43 contralateral CEAs (19% of initial cohort) were performed. Carotid stenosis regressed in 25 arteries (10.7%). Baseline clinical and demographic factors did not predict disease progression. Baseline contralateral stenosis did not predict time to "any progression," but was a strong predictor of "progression to severe stenosis or occlusion" (P <.001).
Conclusions: After CEA, we identified an 8.3% annual rate of progression of contralateral carotid artery stenosis and a 4.4% annual rate of progression to severe stenosis or occlusion. Baseline contralateral stenosis was significantly predictive of progression to severe stenosis or occlusion. Clinical and demographic factors were not helpful in predicting which patients would have disease progression. These data may help in assessing the cost effectiveness of duplex scanning surveillance after CEA.