Carotid artery stenting:the need for randomised trials

Endovascular treatment for carotid artery stenosis avoids some of the complications of carotid endarterectomy, but has not been widely accepted. Concerns about the risks and benefits of endovascular treatment led to the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS). There was no difference in major outcome events between endovascular treatment and carotid endarterectomy, but the rate of procedural stroke or death was higher than desirable. There was no difference either in the rate of stroke during follow-up, but the confidence intervals were very wide and severe ipsilateral carotid stenosis was more frequent 1 year after endovascular treatment than after carotid surgery. Two other randomised trials of carotid stenting were stopped early after poor outcomes in stented patients. These early trials used techniques which have now been superseded, but the results emphasise the need to improve the safety of endovascular treatment. Recent advances designed to improve safety include new designs of stents and delivery systems, and devices designed to protect the brain from embolisation during stenting. However, there is little convincing evidence that these new devices reduce the rate of stroke. Moreover, a systematic review of the existing randomised trial data concluded that there the current evidence does not support a shift away from recommending carotid endarterectomy as the standard treatment for carotid stenosis. There is therefore a clear need for further randomised trials of carotid stenting. Three of the ongoing trials, EVA-3S, SPACE and ICSS (CAVATAS-2), have prospectively agreed to combine individual patient data after completion of follow-up. This meta-analysis will provide results similar to a mega-trial and should also allow informative subgroup analyses. The co-operation between the trials in agreeing to perform this meta-analysis is a major advance in trial design. The result should determine whether carotid stenting truly rivals carotid endarterectomy as the treatment of choice for carotid stenosis.