Carotid artery stent placement for asymptomatic extracranial carotid stenosis - Consultation Document

Interventional procedure consultation document

Carotid artery stent placement for asymptomatic extracranial carotid stenosis

Treating asymptomatic narrowed or blocked carotid arteries using stents

The main arteries in the neck (the carotid arteries) can become narrowed or blocked by fatty deposits. Fragments of these fatty deposits can become detached from the walls of the carotid artery and lodged in thinner arteries that supply blood to parts of the brain, causing a transient ischaemic attack (TIA, sometimes called a ‘mini stroke’) or a stroke. Patients who have this narrowing but have had no health problems resulting from it are described as ‘asymptomatic’.

In this procedure a metal mesh called a stent is used to widen the narrowed carotid artery. This procedure does not involve making a cut in the neck. Instead a fine wire is inserted into an artery in the leg and passed up into the carotid artery, and the stent is then moved into place along the wire. Some stenting also includes protective devices, to help to prevent any fragments loosened by the stent insertion from reaching smaller arteries and causing a stroke.

The National Institute for Health and Clinical Excellence (NICE) is examining carotid artery stent placement for asymptomatic extracranial carotid stenosis and will publish guidance on its safety and efficacy to the NHS in England, Wales, Scotland and Northern Ireland. NICE’s Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisers, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about carotid artery stent placement for asymptomatic extracranial carotid stenosis.

This document summarises the procedure and sets out the provisional recommendations made by the Advisory Committee. It has been prepared for public consultation. The Advisory Committee particularly welcomes:

• comments on the provisional recommendations
• the identification of factual inaccuracies
• additional relevant evidence, with bibliographic references where possible.

Note that this document is not NICE’s formal guidance on this procedure. The recommendations are provisional and may change after consultation.

The process that NICE will follow after the consultation period ends is as follows.

• The Advisory Committee will meet again to consider the original evidence and its provisional recommendations in the light of the comments received during consultation.
• The Advisory Committee will then prepare draft guidance which will be the basis for NICE’s guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.

For further details, see the Interventional Procedures Programme manual, which is available from the NICE website (www.nice.org.uk/ipprogrammemanual).

NICE is committed to promoting through its guidance race and disability equality and equality between men and women, and to eliminating all forms of discrimination. One of the ways we do this is by trying to involve as wide a range of people and interest groups as possible in the development of our guidance on interventional procedures. In particular, we aim to encourage people and organisations from groups in the population who might not normally comment on our guidance to do so. We also ask consultees to highlight any ways in which draft guidance fails to promote equality or tackle discrimination and give suggestions for how it might be improved. NICE reserves the right to summarise and edit comments received during consultations, or not to publish them at all, where in the reasonable opinion of NICE, the comments are voluminous, publication would be unlawful or publication would otherwise be inappropriate.

Closing date for comments: 21 January 2011

Target date for publication of guidance: April 2011

NICE is also consulting on the following procedure: Carotid artery stent placement for symptomatic extracranial carotid stenosis

1   Provisional recommendations

1.1   Current evidence on the safety of carotid artery stent placement for asymptomatic extracranial carotid stenosis shows well documented risks, in particular the risk of stroke. The evidence on efficacy is inadequate in quantity. Therefore this procedure should only be used with special arrangements for clinical governance, consent and audit or research.

1.2  Clinicians wishing to undertake carotid artery stent placement for asymptomatic extracranial carotid stenosis should take the following actions.

• Ensure that patients and their carers understand the uncertainty about the procedure’s efficacy, the risk of stroke and other complications, and the reasons for advising stenting rather than endarterectomy or best medical treatment alone in their particular case. Patients should be provided with clear written information. In addition, the use of NICE’s information for patients (‘Understanding NICE guidance’) is recommended (available from www.nice.org.uk/IPGXXXpublicinfo). [[details to be completed at publication]]

1.3  Patient selection should be carried out by a multidisciplinary team which should include an interventional radiologist or a neuroradiologist, a vascular surgeon and a physician with specialist interest in stroke. Cardiac surgeons and cardiologists should liaise with the multidisciplinary team in relation to patients being considered for this procedure as a prelude to cardiac surgery.

1.4  This procedure should only be carried out by clinicians with specific training and expertise in the technique who regularly perform complex endovascular interventions. The Royal College of Radiologists has produced training standards.

1.5  NICE encourages clinicians either to enter patients into the ACST-2 trial (Asymptomatic Carotid Artery Surgery Trial -2; www.acst.org.uk) or to submit data to the Endovascular Carotid Register, run by the British Society of Interventional Radiology and the Vascular Society of Great Britain and Ireland (www.bsir.org and www.vascularsociety.org.uk). NICE may review this procedure on publication of further evidence.

2   The procedure

2.1  Indications and current treatments

2.1.1  Asymptomatic stenosis of the extracranial carotid arteries due to atherosclerosis may be identified incidentally through imaging – for example before cardiac surgery. Patients with carotid stenosis are at an increased risk of a transient ischaemic attack or stroke; but the risk is lower from asymptomatic stenoses than from symptomatic stenoses.

2.1.2  Good medical control of cardiovascular risk factors is essential.  Severe asymptomatic stenoses are sometimes treated by carotid endarterectomy.

2.2   Outline of the procedure

2.2.1  Carotid stenting is carried out with the patient under local anaesthesia and via a percutaneous transfemoral approach. A guidewire is passed into the carotid artery, often followed by a small balloon catheter to pre-dilate the narrowed artery. A cerebral protection device is usually used to prevent any debris dislodged during stenting from passing into the cerebral circulation. A metal mesh (stent) is inserted to treat the stenosis, and with the aim of preventing both further embolism and restenosis.

2.2.2  Carotid stenting is a less invasive percutaneous procedure than endarterectomy but there has been concern about the risk of stroke caused by embolic material becoming dislodged during the procedure.

Sections 2.3 and 2.4 describe efficacy and safety outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the overview, available at www.nice.org.uk/guidance/IP/881/overview

2.3  Efficacy

The efficacy outcomes described below include stroke or death that occurred more than 30 days after the procedure (unless specified otherwise). These contrast with stroke or death occurring on or before 30 days, which were considered to be safety outcomes.

2.3.1  A randomised controlled trial (RCT) of 2522 patients with either symptomatic or asymptomatic stenosis reported that among asymptomatic patients there was no significant difference in the rate of stroke or death following stenting or endarterectomy (5% vs 3%; hazard ratio [HR] 1.86, 95% confidence interval [CI] 0.95 to 3.66; p = 0.07) at a median 2.5-year follow-up (absolute figures not reported).

2.3.2  A UK national register of 291 asymptomatic patients treated by stenting reported 5-year event rates as follows: stroke 4%; stroke or transient ischaemic attack (TIA) 8%; mortality or disabling stroke 19%, and mortality 18%.

2.3.3  An RCT of 85 asymptomatic patients treated by either stenting (n = 43) or endarterectomy (n = 42) reported that mean carotid artery stenosis was reduced from 86% at baseline to 5% following stenting (absolute figures not stated).

2.3.4  The Specialist Advisers listed key efficacy outcomes as long-term patency and freedom from stroke or death.

2.4   Safety

2.4.1  The UK national register of 291 asymptomatic patients treated by stenting reported a mortality rate of less than 1% (1/181) at 30-day follow-up.

2.4.2  A meta-analysis of 2 studies including 140 asymptomatic patients reported no significant difference in the rate of stroke or death at 30-day follow-up between the stenting group (4% [3/73]) and the endarterectomy group (3% [2/63]); odds ratio 1.06 (95% CI 0.16 to 6.94) (p = 0.96). The UK national register of 291 asymptomatic patients reported a rate of death or disabling stroke of 1% (2/181) at up to 30-day follow-up.

2.4.3  The UK national register of 291 asymptomatic patients reported a rate of disabling stroke of less than 1% (1/181), non-disabling stroke 1% (2/181), TIA 2% (4/181) and myocardial infarction of less than 1% (1/181) at 30-day follow-up. The RCT of 85 asymptomatic patients reported no perioperative strokes or TIAs in either the stenting group or the endarterectomy group.

2.4.4  The UK national register of 291 asymptomatic patients reported 1 or more occurrences of the following complications within 30 days after stenting: ventricular fibrillation arrest during the procedure, hypotension delaying discharge and readmission for raised serum potassium level.

2.4.5  The Specialist Advisers listed anecdotal or reported adverse events related to this procedure as femoral artery damage and renal failure. They considered theoretical adverse events to be dissection, restenosis or contrast allergy/nephrotoxicity.

3   Further information

3.1  This guidance is a review of ‘Carotid artery stent placement for carotid stenosis’ NICE interventional procedures guidance 191 (2006).

3.2  For related NICE guidance see www.nice.org.uk

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee

December 2010

_{Personal data will not be posted on the NICE website. In accordance with the Data Protection Act names will be anonymised, other than in circumstances where explicit permission has been given.}

 _{It is the responsibility of consultees to accurately cite academic work in order that they can be validated.}