Natural history of carotid artery stenosis contralateral to endarterectomy: Results from two randomized prospective trials - Discussion

Purpose: A few nonrandomized studies have reported the natural history of carotid artery stenosis (CAS) contralateral to carotid endarterectomy (CEA). This study analyzed this condition with data from two randomized prospective trials. Methods. The contralateral carotid arteries in 534 patients from two randomized trials that compared CEA with primary closure versus patching were followed up clinically and with duplex ultrasound scanning at I month and then every 6 months. CAS was classified as less than 50%, 50% to 79%, 80% to 99%, and occlusion. Late contralateral CEA was performed to treat significant CAS. Progression was defined as progress to a higher category of stenosis. Kaplan-Meier life table analysis was used to estimate freedom from progression of CAS. The correlation of risk factors and CAS progression was also analyzed. Results. Of 534 patients, 61 had initial contralateral CEA and 53 had contralateral occlusion. Overall, CAS progressed in 109 of 420 patients (26%) at mean follow-up of 41 months. Progression of CAS was noted in 5 of 162 patients (3%) with baseline normal carotid arteries. CAS progressed in 56 of 157 patients (36%) with less than 50% stenosis versus 45 of 95 patients (47%) with 50% to 79% stenosis (P =.003). Median time to progression was 24 months for less than 50% CAS, and 12 months for 50% to 79% CAS (P =.035). At 1, 2, 3, 4, and 5 years, freedom from disease progression in patients with baseline CAS <50% was 95%, 78%,69%,61%,48%, respectively, and in patients with 50% to 79% CAS was 75%,61%, 51%, 43%, and 33%, respectively (P =.003). Freedom from progression in patients with baseline normal carotid arteries at 1 through 5 years was 99%, 98%, 96%, 96%, and 94%, respectively. Late neurologic events referable to the CCA were infrequent (28 of 420 [6.7%] in the entire series; 28 of 258 [10.9%] patients with contralateral CAS), and included 10 strokes (2.4%) and 18 transient ischemic attacks (4.3%). However, late contralateral CEA was performed in 62 patients (62 of 420 [15%] in the entire series; 62 of 258 [24%] patients with contralateral CAS). Survival rates were 96%, 92%, 90%, 87%, and 82%, respectively, at I through 5 years. Conclusions. Progression of CCA stenosis was noted in a significant number of patients with baseline contralateral CAS. Serial clinical studies and duplex ultrasound scanning every 6 to 12 months in patients with 50% to 79% CAS, and every 12 to 24 months in patients with 50% or less CAS is adequate.