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International Carotid Stenting Study: prevention of stroke resulting from carotid artery narrowing
12 December 2014
Narrowing of one carotid artery in the neck (carotid stenosis) is an important cause of stroke. Incorporation of UCL research findings on the treatment of carotid stenosis into national and international guidelines led to an increase in the proportion of patients treated by carotid endarterectomy compared to stenting.
A 20-year programme of clinical trial research, led by Professor Martin Brown (UCL Institute of Neurology), involved the introduction and evaluation of carotid artery stenting (CAS): the insertion of a mesh tube into the artery as a treatment to prevent stroke in patients with carotid artery narrowing (stenosis). He established a study to produce definitive data concerning the risks and benefits of CAS in comparison to carotid endarterectomy (CEA) surgery, known as the International Carotid Stenting Study (ICSS).
Our research has shown that stenting is a good option for younger patients with carotid stenosis, but it is usually safer to treat older patients by endarterectomy. - Professor Martin Brown.
Results of the ICSS presented in 2012 and a meta-analysis of data from all existing trials of CAS undertaken by Professor Brown and colleagues at Basel University confirmed that CAS is associated with an increased risk of peri-procedural stroke or death compared with CEA, but the excess risk is limited to older patients. These findings were incorporated into National Institute for Health and Clinical Excellence (NICE), European, Australasian and North American guidelines on the treatment of carotid stenosis and have also influenced public debate and clinical practice.
For example, in the UK, the 2011, NICE guidelines on treatment of carotid stenosis stated "Current evidence on the safety and efficacy of carotid artery stent placement for symptomatic extracranial carotid stenosis is adequate to support the use of this procedure provided that normal arrangements are in place for clinical governance and audit or research", quoting the published results of ICSS and the meta-analysis in support of the conclusions.
This research provides a vital step in providing another viable option which will help people significantly reduce their stroke risk. - Dr Shamim Quadir, Research Communications Manager at the Stroke Association
In 2008, the 3rd edition of the National Clinical Guidelines for Stroke, published by the Royal College of Physicians stated "Carotid angioplasty or stenting should only be carried out in specialist centres where outcomes of these techniques are routinely audited and preferably as part of a randomised clinical trial." In the 4th edition published in 2012, this changed to read "Carotid endarterectomy should be the treatment of choice for patients with symptomatic carotid stenosis, particularly those who are 70 years of age and over. Carotid angioplasty and stenting should be considered in patients meeting the criteria for carotid endarterectomy but are considered unsuitable for open surgery", quoting the results of ICSS. There has been concern expressed in public debates about the uncontrolled expansion of CAS as an alternative to CEA in the face of the trial evidence. Several recent commentaries and leading articles in prominent medical journals have cited the UCL work. For example, a commentary in the Lancet by a leading expert neurologist entitled "Carotid stenting: more risky than endarterectomy and often no better than medical treatment alone", stated "This excess risk of stroke is highlighted again in each of the three latest reports: the International Carotid Stenting Study (ICSS), the ICSS imaging substudy, and the Carotid Revascularization Endarterectomy versus Stent Trial (CREST)".
In terms of clinical practice, there has been a reported fall in the number of patients treated by CAS after the results of ICSS were published, suggesting the data had a direct impact on the treatment of patients. Within the English NHS, the numbers of patients treated by CAS did not increase between 2006 and 2012, whereas the numbers of patients treated by CEA increased by 30%, a finding consistent with a response to the findings of the UCL trials indicating that CEA was safer than CAS.
The training, proctoring and supervision in CAS that UCL introduced as part of trial protocols ensured that patients treated by CAS have the procedure performed as safely as possible. The perioperative risk of stroke or death from CAS fell by 30% from 2001 to 2010 during the course of the research. As a result of this research, patients can now be accurately informed about the current risks of CAS versus CEA, and together with their doctor can make informed choices about which treatment is the most suited to them. This means better choice for patients, increased safety and improved long-term outcomes.
The main sources of support for the research were the Stroke Association and the Medical Research Council.