Contralateral Carotid Artery Surveillance After Carotid Endarterectomy: Long-term Results From a Large Integrated Regional Health System

Recent guidelines suggest that some patients may not require repeat surveillance imaging if the first postoperative scan after carotid endarterectomy (CEA) is normal. There is some question, however, if releasing a patient from ipsilateral surveillance may result in insufficient surveillance of the contralateral carotid artery. In this retrospective cohort study, we examined the long-term outcomes of the contralateral carotid artery after CEA within a large integrated regional health care system. The artery of interest was the contralateral artery in patients who underwent CEA for severe (70%-99%) carotid artery stenosis from 2008 to 2012 with follow-up through 2019. Patients with prior contralateral intervention, severe contralateral stenosis, or occlusion, and those who died within 30 days postoperatively were excluded. Eligible artery stenosis was defined as mild (1%-49%) or moderate (50%-69%). Primary outcomes were contralateral disease progression to severe stenosis or occlusion, and contralateral ischemic stroke. A competing risk analysis was used to quantify freedom from the primary outcomes. Overall, 1146 carotid arteries underwent CEA during the study period, 624 (54.4%) for symptomatic indication. The mean follow-up was 6.7 years (standard deviation: 3.3 years). At the time of first post-CEA scan, the rates of mild and moderate contralateral carotid artery stenosis were 80.2% (n = 919) and 36.8% (n = 422), respectively. There were 69 (6.0%) contralateral arteries that progressed to severe stenosis during the postoperative period. Of these, 37.7% (n = 26) were mild and 62.3% (n = 43) were moderate at study entry. Overall, 3.8% of patients with mild and 19.1% with moderate stenosis at first post-CEA scan progressed to severe. As for stroke, 37 (3.2%) patients suffered one attributed to disease of the contralateral (non-CEA) artery; 73% of these arteries (n = 27) were mild and 27% (n = 10) were moderate at study entry. A total of 37 (3.2%) patients underwent intervention on the contralateral artery during the follow-up period; 14 (39%) patients had severe stenosis detected during surveillance, and 7 (19%) patients were symptomatic before intervention. The cumulative risk of severe stenosis, occlusion, or contralateral stroke at 5 years was 4.8% (95% confidence interval [CI]: 3.6%-6.3%), 0.2% (95% CI: 0.05%-0.9%), and 1.9% (95% CI: 1.2%-2.9%), respectively. The risk of severe contralateral carotid artery stenosis and stroke after CEA is low. This is important given possible implementation of decreased frequency and duration of post-CEA surveillance. These results confirm that releasing patients from carotid surveillance after one normal postoperative imaging study does not put the patient at high risk of having future severe contralateral carotid artery stenosis go undetected.