The National Institute for Health and Clinical Excellence (NICE) has produced full guidance to the NHS in England, Scotland, Wales and Northern Ireland on carotid artery stenting. According to NICE, “current evidence suggests that stent placement for carotid artery stenosis is safe and efficacious in the short-term. However, long-term efficacy in terms of prevention of stroke and restenosis is unknown, and there are uncertainties about the benefits for asymptomatic patients.”
The Guidance document states that patients must understand the uncertainty surrounding the long-term safety and efficacy of the procedure and provide them with clear written information, and selection of patients for this procedure should involve a multidisciplinary team.
Audit and review clinical outcomes of all patients having carotid artery stent placement are strongly recommended to be recorded into the ongoing International Carotid Stenting Study (ICSS). Procedures performed outside of the ICSS trial are advised to be submitted to the Endovascular Carotid Registry held by the British Society for Interventional Radiology and the Vascular Society of Great Britain and Ireland.
Three meta-analyses have been published that compare stenting and endarterectomy for carotid artery stenosis. The most recent of these involves 1,269 patients (both asymptomatic and symptomatic), 632 of whom were randomised to undergo carotid stenting, and reports on the outcomes of five randomised controlled trials. It was found that there was no significant difference between the two treatments groups in the rate of any stroke or death at one year after the procedure (odds ratio [OR] 1.01; 95% confidence interval [CI] 0.82 to 1.94). However, there was some evidence to suggest that restenosis may be more common after stenting than after endarterectomy. Similar results were observed in a non-randomised controlled study of 397 patients (both asymptomatic and symptomatic), 254 of whom underwent carotid stenting. At 12 months there was no significant difference in the combined death/stroke rate between the stent group (10%) and the endarterectomy group (14%). It was observed that the incidence of restenosis was greater in the stent group, however the difference was not significant.
Studies on this procedure show substantial heterogeneity, making it difficult to interpret the evidence. In particular, there are differences between study populations (asymptomatic vs. symptomatic patients), and earlier studies focused on balloon angioplasty rather than stenting.
According to NICE, analysis of 30-day safety data from five randomised controlled trials comparing stent with endarterectomy for carotid artery stenosis found no significant difference in the odds of any stroke or death (OR 1.33; 95% CI 0.86 to 2.04). The rate of stroke or death within 30 days reported in the non-randomised study series ranged from 5.3% (357/6753) to 10% (15/150) without cerebral protection, and from 1.8% (16/896) to 5.2% (5/97) with cerebral protection. Data from a carotid artery stent registry shows mortality related to the procedure ranged from 0.3% (7/2110) for asymptomatic patients treated with cerebral protection to 1% (43/4282) for symptomatic patients treated without protection.
The Specialist Advisers expressed uncertainty about the efficacy of this procedure in comparison with surgery. They considered that the long-term results were still unknown and that it is still unclear which patients were most likely to benefit from the procedure. One Specialist Adviser was of the opinion that efficacy in asymptomatic patients is not proven.