Optimal Management of Asymptomatic Carotid Artery Stenosis: A Systematic Review and Network Meta-Analysis

Objective: Management of asymptomatic carotid artery stenosis (ACAS), including carotid endarterectomy (CEA), carotid artery stenting (CAS), and best medical treatment (BMT), remains inconsistent in current practice. Early studies reported a benefit of CEA vs. BMT; however, the current risk -benefit profile of invasive therapy lacks consensus. By evaluating the effects of modern BMT vs. invasive intervention on patient outcomes, this study aimed to influence the future management of ACAS.Methods: A systematic review and series of network meta-analyses were performed assessing peri-operative (within 30 days) and long term (30 days -5 years) stroke and mortality risk between ACAS interventions. Total stroke, major, minor, ipsilateral, and contralateral stroke subtypes were assessed independently. Traditional (pre-2000) and modern (post-2000) BMT were compared to assess clinical improvements in medical therapy over the previous two decades. Risks of myocardial infarction (MI) and cranial nerve injury (CNI) were also assessed.Results: Seventeen reports of 14 310 patients with > 50% ACAS were included. CEA reduced the odds of a peri-operative stroke event occurring vs. CAS (odds ratio [OR] 1.6, 95% confidence interval [CI] 1.1 -2.2 [0 -20 fewer/1 000]). CEA and CAS reduced the long term odds of minor strokes (OR 0.35, 95% CI 0.21 -0.59 [20 fewer/1 000]) and ipsilateral strokes (OR 0.27, 95% CI 0.19 -0.39 [30 fewer/1 000]) vs. all BMT. CEA reduced the odds of major strokes and combined stroke and mortality vs. traditional BMT; however, no difference was found between CEA and modern BMT. CAS reduced the odds of peri-operative MI (OR 0.49, 95% CI 0. 26 -0.91) and CNI (OR 0.07, 95% CI 0.01 -0.42) vs. CEA.Conclusion: Modern BMT demonstrates similar reductions in major stroke, combined stroke, and mortality to CEA. The overall risk reductions are low and data were unavailable to assess subgroups which may benefit from intervention. However, BMT carries the potential to reduce the requirement for surgical intervention in patients with ACAS.