Background: Endovascular treatment by transluminal balloon angioplasty or stent insertion may be a useful alternative to carotid endarterectomy for the treatment of atherosclerotic carotid artery stenosis. This review updates a previous version first published in 1997 and subsequently updated in 2004 and 2007.

Objectives: To assess the benefits and risks of endovascular treatment compared with carotid endarterectomy or medical therapy in patients with symptomatic or asymptomatic carotid stenosis.

Search methods: We searched the Cochrane Stroke Group Trials Register (last searched January 2012) and the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 4), MEDLINE (1950 to January 2011), EMBASE (1980 to January 2011) and Science Citation Index (1945 to January 2011). We also searched ongoing trials registers (January 2011) and reference lists and contacted researchers in the field.

Selection criteria: Randomised trials comparing endovascular treatment (including balloon angioplasty or stenting) with endarterectomy or medical therapy for symptomatic or asymptomatic atherosclerotic carotid stenosis.

Data collection and analysis: One review author selected trials for inclusion, assessed trial quality and extracted data. A second review author independently validated trial selection and a third review author independently validated data extraction. We calculated treatment effects as odds ratios (OR) and 95% confidence intervals (CI), with endovascular treatment as the reference group. We quantified heterogeneity using the I(2) statistic.

Main results: We included 16 trials involving 7572 patients. In patients with symptomatic carotid stenosis at standard surgical risk, endovascular treatment was associated with a higher risk of the following outcome measures occurring between randomisation and 30 days after treatment than endarterectomy: death or any stroke (the primary safety outcome) (OR 1.72, 95% CI 1.29 to 2.31, P = 0.0003; I(2) = 27%), death or any stroke or myocardial infarction (OR 1.44, 95% CI 1.15 to 1.80, P = 0.002; I(2) = 7%), and any stroke (OR 1.81, 95% CI 1.40 to 2.34, P < 0.00001;I(2) = 12%). The OR for the primary safety outcome was 1.16 (95% CI 0.80 to 1.67) in patients < 70 years old and 2.20 (95% CI 1.47 to 3.29) in patients ≥ 70 years old (interaction P = 0.02).The rate of death or major or disabling stroke did not differ significantly between treatments (OR 1.28, 95% CI 0.93 to 1.77, P = 0.13; I(2) = 0%). Endovascular treatment was associated with lower risks of myocardial infarction (OR 0.44, 95% CI 0.23 to 0.87, P = 0.02; I(2) = 0%), cranial nerve palsy (OR 0.08, 95% CI 0.05 to 0.14, P < 0.00001; I(2) = 0%) and access site haematomas (OR 0.37, 95% CI 0.18 to 0.77, P = 0.008; I(2) = 27%).The combination of death or any stroke up to 30 days after treatment or ipsilateral stroke during follow-up (the primary combined safety and efficacy outcome) favoured endarterectomy (OR 1.39, 95% CI 1.10 to 1.75, P = 0.005; I(2) = 0%), but the rate of ipsilateral stroke after the peri-procedural period did not differ between treatments (OR 0.93, 95% CI 0.60 to 1.45, P = 0.76; I(2) = 0%).Restenosis during follow-up was more common in patients receiving endovascular treatment than in patients assigned surgery (OR 2.41, 95% CI 1.28 to 4.53, P = 0.007; I(2) = 55%). In patients with asymptomatic carotid stenosis, treatment effects on the primary safety (OR 1.71, 95% CI 0.78 to 3.76, P = 0.18; I(2) = 0%) and combined safety and efficacy outcomes (OR 1.75, 95% CI 0.92 to 3.33, P = 0.09; I(2) = 0%) were similar to symptomatic patients, but differences between treatments were not statistically significant. Among patients not suitable for surgery, the rate of death or any stroke between randomisation and end of follow-up did not differ significantly between endovascular treatment and medical care (OR 0.22, 95% CI 0.01 to 7.92, P = 0.41; I(2)= 79%).

Authors' conclusions: Endovascular treatment is associated with an increased risk of peri-procedural stroke or death compared with endarterectomy. However, this excess risk appears to be limited to older patients. The longer term efficacy of endovascular treatment and the risk of restenosis are unclear and require further follow-up of existing trials. Further trials are needed to determine the optimal treatment for asymptomatic carotid stenosis.