Background: Adults with asymptomatic carotid artery stenosis are at increased risk for ipsilateral carotid territory ischemic stroke.
Purpose: To examine comparative evidence on management strategies for asymptomatic carotid stenosis and the incidence of ipsilateral stroke with medical therapy alone.
Data Sources: MEDLINE, Cochrane Central Register of Controlled Trials, U.S. Food and Drug Administration documents, and review of references through 31 December 2012.
Study Selection: Randomized, controlled trials (RCTs) and prospective or retrospective nonrandomized, comparative studies of medical therapy alone, carotid endarterectomy (CEA) plus medical therapy, or carotid artery stenting (CAS) plus medical therapy for adults with asymptomatic carotid stenosis, as well as single-group prospective cohort studies of medical therapy, were reviewed.
Data Extraction: Two investigators extracted information on study and population characteristics, results, and risk of bias.
Data Synthesis: Forty-seven studies in 56 publications were eligible. The RCTs comparing CAS and CEA were clinically heterogeneous; 1 RCT reported more but not statistically significant ipsilateral stroke events (including any periprocedural stroke) in CAS compared with CEA, whereas another RCT, in a population at high surgical risk for CEA, did not. Three RCTs showed that CEA reduced the risk for ipsilateral stroke (including any periprocedural stroke) compared with medical therapy alone, but these results may no longer be applicable to contemporary clinical practice. No RCT compared CAS versus medical therapy alone. The summary incidence of ipsilateral stroke across 26 cohorts receiving medical therapy alone was 1.68% per year.
Limitations: Studies defined asymptomatic status heterogeneously. Participants in RCTs did not receive best-available medical therapy.
Conclusion: Future RCTs of asymptomatic carotid artery stenosis should explore whether revascularization interventions provide benefit to patients treated by best-available medical therapy.
Primary Funding Source: Agency for Healthcare Research and Quality.