Carotid Artery Disease
Carotid artery disease is atherosclerotic stenosis of the carotid arteries, a major cause of ischaemic stroke and TIA. Carotid endarterectomy is indicated for symptomatic stenosis ≥50%.
Key Facts
Carotid stenosis accounts for ~20-30% of ischaemic strokes Carotid endarterectomy (CEA) should be performed within 14 days of symptoms for symptomatic stenosis ≥50% (NASCET criteria) — NICE CG68 NASCET criteria: Measure stenosis compared to normal distal ICA — 50-69% moderate, 70-99% severe NNT: ~6 for CEA in 70-99% symptomatic stenosis (ECST/NASCET trials); ~22 for 50-69% Asymptomatic stenosis ≥60%: Surgery debated; best medical therapy is increasingly favoured; consider surgery only in high-risk patients in specialist centres Duplex USS: First-line investigation — assesses degree of stenosis and plaque morphology Risk factors: Same as atherosclerosis — smoking, hypertension, diabetes, hyperlipidaemia, age Best medical therapy: Antiplatelet (clopidogrel 75mg), statin (atorvastatin 80mg), antihypertensive, smoking cessation
Overview
Key Facts
Carotid artery disease is a significant and treatable cause of stroke. Timely intervention with CEA in symptomatic patients reduces stroke risk substantially.
Epidemiology
~100,000 strokes/year in UK; ~20-30% caused by carotid disease. Asymptomatic carotid stenosis >50% found in ~5-10% of adults >65.
Aetiology
- Atherosclerosis: ~95% of carotid disease
- Plaque at carotid bifurcation: Low shear stress promotes plaque formation
- Mechanism of stroke: Plaque rupture → thromboembolism to cerebral circulation (artery-to-artery embolism) — more common than haemodynamic compromise from stenosis
Pathophysiology
- Atherosclerotic plaque most commonly at carotid bifurcation where ICA originates
- Plaque vulnerability (lipid-rich core, thin fibrous cap, intraplaque haemorrhage) determines stroke risk
- Emboli travel to MCA territory → cerebral ischaemia
- CEA removes the plaque surgically → eliminates embolic source
Clinical Presentation
Symptomatic Carotid Disease
TIA (resolves within 24 hours):
- Amaurosis fugax (transient monocular blindness — 'curtain descending over eye')
- Hemiparesis, hemisensory loss (contralateral)
- Dysphasia (dominant hemisphere)
Stroke (persistent deficit >24 hours):
- Same territory as TIA but persistent
- MCA territory most common
Asymptomatic
- Bruit on auscultation over carotid bifurcation (not reliable — absent bruit doesn't exclude stenosis; bruit without stenosis possible)
- Incidental finding on imaging
Red Flags
- TIA or crescendo TIA — urgent assessment within 24 hours (ABCD2 score)
- Acute stroke — thrombolysis/thrombectomy if eligible; CEA only after stabilisation
Differential Diagnosis
| Diagnosis | Key Features | Investigation |
|---|---|---|
| Cardioembolic stroke | AF, valvular disease, mural thrombus | ECG, echocardiography |
| Small vessel disease | Lacunar infarcts, hypertension, diabetes | MRI brain |
| Aortic arch atheroma | Source of embolism, often on TOE | TOE |
| Carotid dissection | Young patient, neck pain, Horner's syndrome | CT/MR angiography |
| Vertebrobasilar insufficiency | Vertigo, diplopia, ataxia, drop attacks | CT/MR angiography |
Diagnosis / Investigation
Bedside
- ABCD2 score: Risk stratify TIA (Age, BP, Clinical features, Duration, Diabetes)
- Neurological examination: Document deficits
Bloods
- FBC, U&Es, lipids, HbA1c, glucose: Cardiovascular risk
- Coagulation: Pre-operative
Imaging
- Carotid duplex USS: First-line — non-invasive; assesses stenosis degree and plaque morphology
- CT angiography (CTA): Confirms stenosis degree; pre-operative planning
- MR angiography (MRA): Alternative if CTA contraindicated
- CT/MRI brain: Assess infarction territory
- ECG/echocardiography: Exclude cardiac source
Stenosis Grading (NASCET)
- Percentage = (1 − narrowest ICA diameter / normal distal ICA diameter) × 100
Management
Symptomatic Carotid Stenosis
70-99% stenosis:
- CEA within 14 days of symptoms (NICE CG68) — NNT ~6 to prevent 1 stroke over 5 years
- Delay beyond 14 days significantly reduces benefit
50-69% stenosis:
- CEA offers modest benefit (NNT ~22) — consider based on patient factors
- Greater benefit in men, older patients, cortical (vs retinal) events
<50% stenosis:
- Best medical therapy only — CEA not beneficial
Near-occlusion (99%) or occlusion:
- CEA not indicated for complete occlusion
- Near-occlusion: Individual decision; benefit unclear
Asymptomatic Stenosis
- Best medical therapy: First-line in most cases
- Atorvastatin 80mg, clopidogrel 75mg, antihypertensive, smoking cessation
- CEA: Consider only in specialist centres for patients with ≥60% stenosis AND additional high-risk features AND expected perioperative risk <3%
- ACST-2 trial results suggest medical therapy may be comparable to surgery in asymptomatic patients
Carotid Artery Stenting (CAS)
- Alternative to CEA in selected patients (high surgical risk, post-radiotherapy neck, recurrent stenosis)
- Similar long-term outcomes to CEA but higher perioperative stroke risk (ICSS, CREST trials)
Referral Criteria
- Symptomatic carotid stenosis ≥50% — urgent vascular surgery referral
- TIA/stroke with carotid territory symptoms — rapid access TIA clinic/stroke team
Prognosis
- CEA for 70-99% symptomatic: Reduces 5-year stroke risk from ~26% to ~9%
- Perioperative stroke/death risk: ~2-3% in experienced centres (audit requirement)
- Benefit diminishes with delay — maximal if done within 14 days; minimal after 12 weeks
- Asymptomatic stenosis: Annual stroke risk ~1-2% with modern medical therapy (much lower than in original trials)
- Long-term: Re-stenosis ~5-10% at 5 years after CEA; higher after CAS
Other Relevant Information
Key Trials in Carotid Surgery
| Trial | Key Finding |
|---|---|
| NASCET | CEA beneficial for symptomatic 70-99% stenosis (NNT ~6) |
| ECST | Confirmed NASCET findings in European population |
| ACST-1 | CEA reduces stroke risk in asymptomatic ≥60% stenosis |
| ACST-2 | CEA vs CAS in asymptomatic — ongoing/recent results |
| ICSS | CAS has higher perioperative stroke rate than CEA (symptomatic) |
| CREST | CEA and CAS similar long-term outcomes; CAS higher stroke, CEA higher MI |