Editorials
Cardiovascular diseases Neurology Vascular diseases
Volume 193 - Issue 8

Stenting for carotid artery stenosis: festina lente . . . hasten slowly

Authors:  Christopher F Bladin, on behalf of the Carotid Stenting Guidelines Committee (Australia and New Zealand)

Med J Aust 2010; 193 (8): 437-438. || doi: 10.5694/j.1326-5377.2010.tb03995.x
Published online: 18 October 2010
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Carotid artery stenting has a place in managing symptomatic stenosis, but only sometimes

Carotid stenosis remains one of the most readily treatable causes of ischaemic stroke. Its treatment has undergone many changes in recent years, with the advent of endovascular techniques seeming to offer great promise of a much less invasive procedure.

In the late 1990s, the Australian Association of Neurologists published guidelines for the use of carotid balloon angioplasty alone (ie, without stenting) as a treatment for carotid stenosis, recommending cautious use in the absence of data from randomised controlled trials (RCTs).1 However, advances in vascular stent technology have resulted in a greatly increased use of carotid artery stenting (stenting), often with specialised filter devices deployed distal to the carotid stenosis to catch embolic debris that may arise from catheter or stent manipulation.

Recent evidence from RCTs has cast doubt on the safety of widespread use of stenting for the treatment of patients with symptomatic or asymptomatic carotid stenosis. The overall results from these RCTs indicate that carotid endarterectomy (endarterectomy) is still the preferred treatment option for symptomatic carotid stenosis. The results of three major European studies into the treatment of symptomatic stenosis — Endarterectomy versus Angioplasty in Patients with Symptomatic Severe Carotid Stenosis (EVA-3S); Stent-Protected Angioplasty versus Carotid Endarterectomy (SPACE); International Carotid Stenting Study (ICSS) — showed that stenting was more hazardous than endarterectomy for the outcomes of stroke and death during the periprocedural period (30 days), and on longer-term follow-up.2-4 Perhaps in contrast, the recent North American Carotid Revascularization Endarterectomy vs Stenting Trial (CREST) demonstrated equivalent (non-significant) rates of stroke, myocardial infarction and death in its stenting and endarterectomy groups in the periprocedural period, and at 4 years.5 However, in CREST there was a significantly reduced rate of stroke and death in the endarterectomy group, but this was offset by an increased risk of myocardial infarction, in part due to the definition of myocardial infarction used, and a greater number of study patients with comorbid ischaemic heart disease.5

Use of cerebral protection devices during stenting was mandated in CREST but not in the European studies. The value of these devices is in question, with evidence indicating that they were no more effective in reducing the clinical risk of stroke than unprotected stenting.6,7 Moreover, data from a magnetic resonance imaging substudy undertaken as part of the ICSS indicated that, compared with endarterectomy, there was a threefold increase in silent brain infarctions in stenting with use of cerebral protection devices (adjusted odds ratio, 3.28 [95% CI, 1.5–7.2]).7 A meta-analysis of 11 RCTs (including EVA-3S, SPACE and ICSS, but not CREST) showed that endarterectomy was superior to stenting in short-term but possibly not longer-term outcomes, a difference largely driven by non-disabling stroke.8 The Australasian guidelines9,10 have now been upgraded following additional published data from CREST5 and a meta-analysis of the three large European trials (EVA-3S, SPACE, ICSS)11 indicating that stenting is at least as safe as endarterectomy in patients under 70 years of age, while it presents a greater risk of stroke for those older than 70 years (Box).

The RCTs indicate that there is currently no clear evidence to support either endarterectomy or stenting as a treatment for asymptomatic carotid stenosis. Indeed, current medical therapies have reduced the risk of stroke in asymptomatic stenosis to as low as 0.5% per year.12 Ongoing RCTs continue to address this question (eg, the Asymptomatic Carotid Surgery Trial 2, comparing stenting and endarterectomy in the treatment of asymptomatic carotid stenosis).13

Until recently, in Australia and New Zealand, there were no specific published guidelines for carotid artery stenting. To redress this, an intercollegiate working group was formed — the Carotid Stenting Guidelines Committee — comprising expert representatives of the Royal Australasian College of Physicians, the Royal Australasian College of Surgeons, and the Royal Australian and New Zealand College of Radiologists. Consensus for guideline parameters was reached using the modified Delphi consensus method of iterative consultation. The committee’s guidelines recommend clinical selection criteria for carotid artery stenting, as well as cognitive and technical requirements that clinicians should meet before performing stenting.9,10 The guidelines do not deal with training criteria and procedural accreditation as these are determined by the Conjoint Committee for Recognition of Training in Peripheral Endovascular Therapy of the abovementioned colleges. On current evidence, the guidelines recommend that carotid artery stenting may be considered a treatment option in specific, high-risk patients with symptomatic severe stenosis who are considered unsuitable for endarterectomy (Box).10 It is important to note that these are relative contraindications to endarterectomy as there is no evidence to support stenting in these patients (indeed, they are often excluded from clinical trials).

Finally, it is important that all patients being considered for a carotid intervention have preprocedural neuroimaging and independent neurological assessment before and after the procedure. This allows for an audit comparison with the results of RCTs where neurological evaluation of all patients is routine, and serves as a benchmark for best clinical practice.

In summary, the evidence from RCTs indicates that, at present, a cautious approach should be taken to recommending carotid artery stenting — festina lente (hasten slowly). Stenting should not be performed in most patients with symptomatic severe carotid stenosis, and there is currently no evidence to support stenting as a treatment for asymptomatic carotid stenosis. Stenting warrants consideration in younger patients (< 70 years of age) and those with symptomatic severe carotid stenosis unsuitable for endarterectomy. These standards should apply in all health care settings, public and private. Advances in endovascular technologies, and evidence from future RCTs and meta-analyses, will guide revisions of the guidelines.

Carotid Stenting Guidelines Committee: recommended indications and contraindications for carotid artery stenting (CAS)10

Indications

Contraindications

* Severe carotoid stenosis is defined as ≥ 70% using North American Symptomatic Cartoid Endarterectomy Trial criteria.5

Author

  • Christopher F Bladin MD, BSc, FRACP1
  • 1. Department of Neurosciences, Box Hill Hospital (Monash University), Melbourne, VIC.

Correspondence: chris.bladin@easternhealth.org.au

Competing interests

Christopher Bladin has received payment from Pfizer for reviewing applications for grants and from Sanofi-Aventis to cover travel and accommodation expenses to attend a medical conference.

References

View this article on Wiley Online Library

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