Carotid endarterectomy for asymptomatic carotid stenosis

Whilst carotid endarterectomy (CEA) is of proven benefit in recently symptomatic patients with severe carotid stenosis, the role of carotid endarterectomy in preventing stroke in patients with asymptomatic carotid stenosis remains uncertain.

The objective of this review therefore was to determine the effects of CEA for patients with asymptomatic carotid stenosis.

We searched the Cochrane Stroke Group Trials Register (June 1998), Medline (1966-Mar 1998), Current Contents (1995-Jan 1997), and reference lists of relevant articles. We contacted researchers in the field to identify additional published and unpublished studies.

All completed randomised trials comparing CEA to medical treatment in patients with asymptomatic carotid stenosis.

Two reviewers extracted data and assessed trial quality. Attempts were made to contact investigators to obtain missing information.

Six trials were identified, but two were excluded on methodological grounds. Four trials with 2203 patients were included. In two trials aspirin was only given to patients in the medical group, and in two all patients received aspirin. The net excess "perioperative stroke or death" rate in the surgical group was 2.7% with relative risk 6.52 (95% confidence interval 2.66-15.96). The rates of "perioperative stroke or death or subsequent ipsilateral stroke" were 6.8% in the medical group vs 4.9% in the surgical group with RR 0.73 (0.52-1.02) favouring surgery. The rates of "any stroke or perioperative death" were 10.4% (medical) vs 8.1% (surgical) with RR 0.79 (0.60-1.02). The rates of "any stroke or death" were 23.2% (medical) vs 20.2% (surgical) with RR 0.89 (0.76-1.04). There were too few patients in CEA vs aspirin trials to determine whether aspirin had any confounding effect on outcome. An additional analysis including data from a fifth small unpublished trial altered slightly the risk ratios in favour of surgery and narrowed confidence intervals sufficiently to achieve statistical significance for each outcome. However, inclusion of these data had no appreciable effect on relative or absolute risk reduction.

There is some evidence favouring CEA for asymptomatic carotid stenosis, but the effect is at best barely significant, and extremely small in terms of absolute risk reduction.