Carotid artery stenosis

What is carotid artery stenosis?¹

Carotid atherosclerosis is one of the main risk factors for ischaemic cerebrovascular events (CVEs). Carotid aherosclerosis causes about 90% of carotid artery stenosis but other much less common causes include aneurysms, arteritis, carotid dissection, coils and kinks, fibromuscular dysplasia and vasospasm.

The area of the carotid artery most commonly affected by atherosclerosis is the bifurcation of the common carotid artery.

Carotid endarterectomy is strongly recommended for severe symptomatic stenosis but not routinely recommended for asymptomatic patients or lesser degrees of stenosis. Trials define symptomatic patients as those having transient ischaemic attacks (TIAs) or minor strokes within three months of entry into the trial.

How common is carotid artery stenosis? (Epidemiology)²

Carotid artery stenosis accounts for approximately 20% of cases of acute ischaemic stroke.¹

Moderate-to-severe asymptomatic carotid atherosclerotic stenosis occurs in 2-5% of European women and 2-8% of European men aged over 60 years. The prevalence is much higher in high-risk groups.

Risk factors

• Increasing age.

• Smoking.

• High systolic blood pressure.

• Total cholesterol.

Carotid artery stenosis symptoms (presentation)^{1 2}

• When symptomatic, the neurological vascular territory commonly affected is the anterior circulation of the brain, causing symptoms such as hemiplegia, dysphasia or vision loss.

• Patients may present with TIAs or CVEs.

• Typical symptoms are contralateral weakness or sensory disturbance, ipsilateral loss of vision, and (if the dominant hemisphere is involved) dysphasia, aphasia or speech apraxia.

• Cognitive impairment and decline may be associated with asymptomatic stenosis of the left internal carotid artery.³

• Asymptomatic patients may be identified when a carotid bruit is heard on physical examination or incidentally on imaging.

Signs

• Detection of a carotid bruit is a common physical examination finding that may lead to a referral for carotid duplex ultrasound.

• Carotid bruits are not sensitive or specific enough to confirm or exclude significant carotid stenoses.⁴ Absence of carotid bruit in patients with cardiovascular disease does not exclude a carotid stenosis.

• A carotid 'bruit' may also be caused by a cardiac murmur transmitted to the neck or may be due to stiff, calcified or tortuous vessels in the absence of stenosis.

Investigations²

• Colour duplex ultrasound is a safe and effective initial investigation to characterise the atheroma and quantify luminal stenosis. However, although colour duplex ultrasound has high sensitivity, it only has moderate specificity.

• Further assessment, such as using multidetector CT angiography or MR angiography, is recommended prior to endarterectomy.

• Other investigations include:

  • FBC, electrolytes, renal function, lipid profile.

  • Electrocardiogram: evidence of prior myocardial infarction and ischaemic changes (the most common cause of mortality following carotid endarterectomy is myocardial infarction).

  • CT scan or MRI of the brain: for all symptomatic patients, in order to rule out other intracranial lesions and identify the presence of new and old cerebral infarcts.

The Royal College of Physicians recommends that people with non-disabling carotid artery territory stroke or TIA should be considered for carotid revascularisation, and should have carotid imaging (duplex ultrasound, MR or CT angiography) performed urgently to assess the degree of stenosis. If the initial test identifies a relevant severe stenosis (greater than or equal to 50%), a second or repeat non-invasive imaging investigation should be performed to confirm the degree of stenosis. This confirmatory test should be carried out urgently to avoid delaying any intervention.⁵

Associated diseases

Carotid arterial stenosis is associated with all presentations of cardiovascular disease (including CVEs, angina, acute coronary syndrome and peripheral arterial disease) as well as conditions predisposing to cardiovascular disease (including diabetes mellitus, hypertension and hyperlipidaemia).

Carotid artery stenosis treatment and management

See also the separate Cerebrovascular Events and Transient Ischaemic Attacks articles regarding the management of symptomatic carotid artery stenosis.

Best medical management of carotid stenosis includes lowering of blood pressure, treatment with statins and antiplatelet therapy in symptomatic patients.⁶ See also the separate Stroke Prevention and Prevention of Cardiovascular Disease articles.

Surgical

• Carotid endarterectomy (surgical removal of the fatty deposits and blood clots from inside the carotid artery wall):
  

  • A Cochrane review found:⁷

    • Carotid endarterectomy reduced the risk of recurrent stroke for people with significant stenosis.

    • Endarterectomy might be of some benefit for participants with 50% to 69% symptomatic stenosis (moderate-quality evidence).

    • Endarterectomy might be highly beneficial for those with 70% to 99% stenosis (moderate-quality evidence).

  • Despite a 3% perioperative stroke or death rate, carotid endarterectomy for asymptomatic carotid stenosis reduces the risk of any stroke by approximately 30% over three years. However, the absolute risk reduction is small (1% per annum over the first few years of follow-up in trials).⁸

  • Symptomatic patients with 50-99% stenosis on duplex ultrasound should be referred urgently for consideration of confirmatory imaging and endarterectomy. It is recommended that surgery is performed within one week and ideally within 48 hours, when stroke is most common and the benefit from endarterectomy is greatest.²

• Carotid angioplasty and stenting:
  

  • Stenting with the use of an emboli protection device is a less invasive revascularisation strategy than endarterectomy in carotid artery disease.

  • For patients with severe carotid artery stenosis and co-existing conditions, carotid stenting with the use of an emboli protection device appears to be as safe and as effective as carotid endarterectomy.⁹

  • One meta-analysis has reported that carotid endarterectomy is superior to endovascular treatment for short-term outcomes. However, stenting was associated with significantly fewer cranial nerve and myocardial complications.¹⁰

  • One study, however, has shown that angioplasty can be as effective as carotid endarterectomy over three years at preventing stroke, with similar major risks.¹¹

  • Carotid artery stenting has not been shown to be superior to best medical treatment in asymptomatic carotid stenosis.¹²

The Royal College of Physicians recommends:⁵

• People with non-disabling carotid artery territory stroke or TIA should be considered for carotid revascularisation if the symptomatic internal carotid artery has a stenosis of greater than or equal to 50%. The decision to offer carotid revascularisation should be based on individualised risk estimates taking account of factors such as the time from the event, gender, age and the type of qualifying event, and supported by risk tables or web-based risk calculators.

• People with non-disabling carotid artery territory stroke or TIA and a carotid stenosis of less than 50% should not be offered revascularisation of the carotid artery.

• Carotid endarterectomy for people with symptomatic carotid stenosis should be:

  • The treatment of choice, particularly for people who are 70 years of age and over or for whom the intervention is planned within seven days of stroke or TIA.

  • Performed in people who are neurologically stable and who are fit for surgery using either local or general anaesthetic according to the person’s preference.

  • Performed as soon as possible and within one week of first presentation.

  • Deferred for 72 hours in people treated with intravenous thrombolysis.

• Carotid angioplasty and stenting should be considered for people with symptomatic carotid stenosis who are unsuitable for open surgery (eg, high carotid bifurcation, symptomatic re-stenosis following endarterectomy, radiotherapy-associated carotid stenosis), or less than 70 years of age and who have a preference for carotid artery stenting.

• Patients with atrial fibrillation and symptomatic internal carotid artery stenosis should be managed for both conditions unless there are contra-indications.

• Surgery or angioplasty/stenting should not be routinely performed for patients with asymptomatic carotid artery stenosis.

Prognosis²

Studies have found that ipsilateral stroke rates associated with asymptomatic carotid stenosis are less than 1% a year. However, there is a greater risk of death from coronary heart disease.

Carotid artery stenosis prevention

For primary prevention of cardiovascular disease, see the separate article Cardiovascular Risk Assessment.