Carotid Artery Disease: Screening, Medical Therapy and Revascularisation

Definition and Pathophysiology

Carotid artery stenosis is an atherosclerotic narrowing of the carotid arteries. It forms part of multisite artery disease, defined as atherosclerosis affecting at least two vascular beds. Carotid disease therefore commonly coexists with coronary artery disease (CAD), peripheral artery disease (PAD), and other manifestations of systemic atherosclerosis.

The principal clinical concern is cerebral embolism or haemodynamic compromise leading to transient ischaemic attack (TIA) or stroke. The risk associated with asymptomatic disease depends substantially on stenosis severity and plaque characteristics. In the general population, the prevalence of asymptomatic carotid stenosis of at least 70% is low, reported as 0–3.1%. In contrast, within selected high-risk populations, prevalence may be sufficiently high for targeted screening to be cost-effective.

For asymptomatic stenosis of at least 70%, the reported 5-year ipsilateral stroke risk is 14.6%, and revascularisation may be beneficial in appropriately selected patients. In diabetes, carotid plaque prevalence correlates linearly with diabetes and carotid atherosclerosis tends to be more advanced than in people without diabetes.

Carotid disease is also a marker of systemic cardiovascular risk. The presence of a carotid bruit is associated with approximately double the risk of myocardial infarction and cardiovascular death. Management must therefore address both cerebrovascular risk and the broader atherosclerotic burden.

Clinical Presentation and Symptoms

Asymptomatic disease

Many patients with carotid stenosis have no focal neurological symptoms. Asymptomatic disease may be discovered during targeted duplex ultrasound (DUS), pre-operative assessment, or evaluation of other atherosclerotic disease.

Routine population screening is not recommended because the prevalence of severe asymptomatic stenosis is low, screening has not been shown to reduce stroke risk, and detection may lead to inappropriate anxiety and invasive procedures.

Symptomatic disease

Symptoms of carotid disease include:

• TIA;

• ischaemic stroke;

• focal neurological symptoms attributable to the affected carotid territory.

Recent neurological symptoms are particularly important in determining management. The benefit of carotid revascularisation is greatest in patients with a recent TIA or stroke, particularly when the event occurred within 3 months and the ipsilateral stenosis exceeds 70%.

Patients being assessed before non-cardiac surgery should be questioned specifically about neurological symptoms during the preceding 6 months. Those with symptoms suggestive of TIA or stroke require neurological consultation and, when appropriate, neurovascular and brain imaging.

Evaluation and Physical Examination

Clinical history and examination are the initial components of assessment. The history should include:

• previous TIA or stroke;

• symptoms suggesting current or recent cerebral ischaemia;

• known CAD, PAD, or other atherosclerotic disease;

• diabetes and other cardiovascular risk factors;

• smoking, hypertension, hypercholesterolaemia, and sedentary behaviour;

• family history, particularly in the broader assessment of peripheral arterial and aortic disease;

• planned surgery, especially carotid endarterectomy (CEA), coronary artery bypass grafting (CABG), or major non-cardiac surgery.

The vascular examination should include:

• palpation of peripheral pulses;

• auscultation for carotid, femoral, and abdominal bruits;

• bilateral brachial blood-pressure measurement;

• cardiac auscultation;

• inspection of the legs and feet.

A systolic blood-pressure difference between the arms exceeding 15 mmHg is associated with a 50% higher risk of cardiovascular death. Bilateral arm blood-pressure measurement is therefore recommended in the vascular assessment.

A carotid bruit is an important marker of cardiovascular risk, although the source material does not provide diagnostic sensitivity or specificity for bruit detection. Its presence should prompt assessment of the patient’s overall vascular risk and consideration of appropriate non-invasive evaluation.

Screening for Carotid Artery Stenosis

Screening in the general population

Widespread screening for asymptomatic carotid stenosis is not recommended. The low prevalence of severe disease means that population screening does not reduce stroke risk and may expose patients to unnecessary psychological distress and invasive procedures.

Selective screening may be reasonable in highly selected populations in which the expected prevalence of significant stenosis is at least 20%. The objective of selective screening is primarily to identify patients who would benefit from prevention and risk-factor modification, rather than simply to identify candidates for revascularisation.

Patients with diabetes

Regular carotid screening is not recommended for patients with diabetes who have no history of cerebrovascular disease because evidence that screening improves outcomes is limited. Screening has been suggested in selected men with diabetes who also have CAD or an ankle–brachial index below 0.85, reflecting a higher likelihood of carotid atherosclerosis.

Asymptomatic carotid disease in patients with diabetes is frequently managed conservatively, with follow-up using DUS.

Patients undergoing CABG

Carotid DUS may be useful before elective CABG, although the approach should be selective rather than universal. Screening is particularly relevant in patients with:

• a history of TIA or stroke;

• PAD;

• age over 65 years;

• carotid bruit;

• multivessel CAD.

Two studies suggested that restricting DUS to patients with at least one such risk factor identifies most patients with significant stenosis, defined as at least 70%.

For stable patients scheduled for CABG who experienced TIA or stroke within the preceding 6 months and have not undergone carotid revascularisation, carotid DUS should be considered. In stable patients without TIA or stroke within the preceding 6 months, DUS may be considered, but the recommendation is weaker.

The addition of CEA to CABG has not consistently reduced stroke. In patients with severe carotid stenosis undergoing staged or combined procedures, reported in-hospital stroke and 30-day mortality were similar to those observed with isolated CABG. Accordingly, the decision to perform carotid intervention should be individualised rather than based solely on the presence of stenosis.

Patients with carotid stenosis undergoing CEA

Because CAD is common in patients scheduled for elective CEA, pre-operative assessment for CAD, including coronary angiography when clinically suspected, may be considered. Coronary and carotid revascularisation should be prioritised according to the patient’s clinical status and the severity of each vascular lesion.

In general, coronary revascularisation should be performed first. The principal exception is a patient with recently symptomatic and unstable neurological disease, in whom carotid revascularisation should take priority.

Patients undergoing non-cardiac surgery

Patients undergoing non-cardiac surgery should be screened clinically for recent neurological symptoms. If a TIA or stroke occurred within 6 months, neurological consultation and appropriate neurovascular and brain imaging are advised.

In symptomatic carotid disease, recent symptoms and high-grade stenosis confer particularly substantial benefit from carotid revascularisation. In patients with a TIA or stroke within the preceding 3 months and stenosis greater than 70%, carotid revascularisation should generally precede elective non-cardiac surgery, which should be postponed.

The role of prophylactic carotid revascularisation in patients with severe asymptomatic carotid occlusive disease undergoing major elective non-cardiac surgery remains unsettled. If carotid revascularisation is otherwise indicated, it may be performed before or after the planned operation. In this setting, its purpose is principally long-term stroke prevention rather than reduction of peri-operative stroke risk.

Diagnostic Assessment

Duplex ultrasound

DUS is the principal non-invasive test referred to in the source material for assessment of carotid stenosis. It is used for:

• selective screening in high-risk populations;

• assessment of suspected carotid disease;

• surveillance of conservatively managed asymptomatic disease;

• pre-operative evaluation in selected CABG patients.

The source material does not provide specific velocity criteria, plaque classifications, or detailed accuracy estimates for DUS.

Neurovascular and brain imaging

Patients with recent symptoms suggestive of TIA or stroke should undergo neurovascular and brain imaging when appropriate. The material does not specify preferred imaging modalities or protocols.

Additional vascular imaging

For suspected peripheral atherosclerosis, assessment begins with non-invasive DUS, followed by computed tomography angiography or magnetic resonance angiography if needed. This broader vascular approach may help identify associated disease but systematic screening of asymptomatic additional vascular territories has not been shown to improve outcomes.

Coronary assessment

In patients with symptomatic PAD, CAD evaluation may be performed with stress testing or coronary computed tomography. Systematic CAD screening in stable PAD has not been shown to improve outcomes, and coronary angiography is less suitable because of its invasive nature.

In patients scheduled for carotid endarterectomy who are suspected of having CAD, coronary evaluation, including angiography, may be considered.

The source material does not address a specific role for electrocardiography or electrophysiological testing in carotid artery disease.

Biomarkers and Laboratory Findings

Laboratory evaluation in patients with peripheral arterial and aortic disease, including those with carotid atherosclerosis, should include:

• a lipid profile;

• lipoprotein(a) at least once during the patient’s lifetime;

• fasting glucose;

• glycated haemoglobin;

• renal function;

• complete blood count;

• coagulation studies;

• liver function;

• electrolytes;

• inflammatory markers, including C-reactive protein and erythrocyte sedimentation rate.

Thyroid-function testing may be added when clinically indicated.

Inflammatory biomarkers, metabolomic profiles, and proteomic markers may have prognostic value in peripheral arterial disease, but the source material does not establish their use for routine carotid disease management or provide validated thresholds.

Medical Therapy and Risk-Factor Management

General principles

Medical treatment is required whether or not revascularisation is performed. Carotid stenosis is a manifestation of systemic atherosclerosis, and treatment should address the patient’s global cardiovascular risk.

Modifiable risk factors include:

• cigarette smoking;

• diabetes;

• hypertension;

• hypercholesterolaemia;

• physical inactivity.

Patients with carotid disease benefit from aggressive cardiovascular risk-factor modification, including when carotid disease is identified during preparation for surgery.

Lipid lowering

For patients with peripheral vascular disease, an LDL-cholesterol reduction of at least 50% from baseline and an LDL-cholesterol target below 1.4 mmol/L, or below 55 mg/dL, are recommended. This recommendation is classified as Class I, Level A.

Although the source material does not provide a carotid-specific lipid target distinct from the peripheral vascular disease recommendation, carotid atherosclerosis is part of the same systemic vascular disease spectrum.

Antithrombotic treatment

In patients with stable peripheral vascular disease who are symptomatic in at least one vascular territory and do not have a high bleeding risk, combined treatment with rivaroxaban 2.5 mg twice daily and aspirin 100 mg once daily should be considered. This is a Class IIa, Level A recommendation.

The source material does not provide a universal antiplatelet regimen specifically for all patients with carotid stenosis, nor does it define antithrombotic treatment after CEA or carotid artery stenting.

Patients with PAD and newly diagnosed atrial fibrillation who have a CHA2DS2-VASc score of at least 2 should receive full oral anticoagulation. This is a Class I, Level C recommendation. The indication is driven by atrial fibrillation and thromboembolic risk rather than carotid stenosis alone.

Lifestyle and vascular prevention

The source material identifies smoking, diabetes, hypertension, hypercholesterolaemia, and sedentary behaviour as modifiable contributors to vascular disease. It also emphasises the importance of preventive and therapeutic strategies for vascular health. Specific dietary targets, exercise prescriptions, blood-pressure thresholds, and smoking-cessation pharmacotherapy are not provided.

Indications for Carotid Revascularisation

Symptomatic stenosis

In symptomatic patients:

• revascularisation is indicated when stenosis exceeds 70%, provided the estimated peri-operative stroke or death risk is below 6%;

• revascularisation should be considered when stenosis exceeds 50%, again assuming a peri-operative stroke or death risk below 6%.

The benefit is particularly high when the TIA or stroke is recent, especially within 3 months.

Asymptomatic stenosis

In asymptomatic patients, carotid revascularisation should be considered when one or more features indicate increased stroke risk, including:

• previous TIA or stroke;

• ipsilateral silent cerebral infarction;

• progression of stenosis;

• high-risk plaque characteristics.

Additional selection criteria include:

• an estimated peri-operative stroke or death risk below 3%;

• life expectancy exceeding 5 years.

The decision must balance the expected long-term stroke-prevention benefit against procedural risk, comorbidity, age, life expectancy, and the quality of contemporary medical therapy.

Choice of Revascularisation: CEA and CAS

Carotid endarterectomy

CEA is the principal revascularisation strategy discussed for patients who meet criteria for intervention. In older adults, particularly those aged 70 years or more, CEA is favoured over carotid artery stenting when revascularisation is indicated.

The source material reports that diabetes is associated with a higher risk of peri-operative stroke and death in observational data. Diabetes also predicted restenosis after both carotid stenting and CEA. Reported restenosis rates at 2 years were low and similar between the two procedures, at 6.0% after stenting and 6.3% after CEA.

Carotid artery stenting

Carotid artery stenting is less invasive than CEA, but comparative data indicate a higher risk of the composite outcome of stroke, myocardial infarction, or death among patients aged 70 years or older. This finding was supported by both the CREST trial and a subsequent meta-analysis.

Accordingly, in patients aged at least 70 years who meet criteria for carotid revascularisation, CEA should generally be selected over CAS.

The source material does not specify anatomical indications, contraindications, peri-procedural antiplatelet protocols, or technical details for CAS.

Management in Combined Coronary and Carotid Disease

Carotid disease before CABG

Carotid DUS should be considered in stable CABG candidates who have had a TIA or stroke within the previous 6 months and have not undergone carotid revascularisation. DUS may also be considered in stable CABG candidates without a recent neurological event, particularly when risk factors such as PAD, carotid bruit, age over 65 years, or multivessel CAD are present.

The presence of carotid stenosis does not automatically justify combined or staged carotid intervention. Evidence cited in the source material indicates that adding CEA to CABG may not significantly reduce stroke compared with CABG alone.

CAD before CEA

Because CAD is prevalent among patients undergoing elective CEA, suspected CAD may warrant pre-operative assessment, including coronary angiography when appropriate. Coronary revascularisation is generally performed before carotid revascularisation, except when neurological symptoms are recent and unstable.

PAD and CAD

In patients with PAD, CAD assessment may help optimise medical treatment, but systematic screening in stable PAD has not been shown to improve outcomes or to justify increased coronary intervention. Assessment may nevertheless be considered in patients scheduled for open vascular surgery who have poor functional capacity, substantial risk factors, or symptoms.

Peri-operative Considerations

Patients with carotid artery stenosis should receive intensive cardiovascular risk-factor modification to reduce peri-operative myocardial ischaemia when undergoing surgery.

For symptomatic carotid disease with recent TIA or stroke and severe stenosis, carotid treatment should generally precede elective non-cardiac surgery. For severe asymptomatic disease, the decision is primarily one of long-term stroke prevention; carotid intervention may occur before or after non-cardiac surgery if intervention is otherwise indicated.

In patients undergoing TAVI, screening for ilio-femoral PAD is recommended, reflecting the importance of associated peripheral vascular disease in procedural planning. This is a Class I, Level B recommendation.

Guideline Recommendations

For carotid revascularisation, the source material describes the following decision thresholds:

• symptomatic stenosis greater than 70%: revascularisation is indicated when peri-operative stroke or death risk is below 6%;

• symptomatic stenosis greater than 50%: revascularisation should be considered when peri-operative stroke or death risk is below 6%;

• asymptomatic disease: revascularisation should be considered in patients with increased stroke-risk indicators, peri-operative stroke or death risk below 3%, and life expectancy greater than 5 years.

Prognosis and Follow-up

Carotid stenosis is a marker of increased systemic cardiovascular risk, including myocardial infarction and cardiovascular death. The presence of carotid disease should therefore prompt assessment for associated CAD and PAD when clinically indicated, although routine screening of all additional vascular territories is not supported by evidence of improved outcomes.

The prognosis of asymptomatic disease depends on stenosis severity, progression, plaque risk features, comorbidity, and the intensity of medical prevention. Severe asymptomatic stenosis of at least 70% is associated with a substantially increased 5-year ipsilateral stroke risk.

Asymptomatic carotid disease is often treated conservatively with medical therapy and surveillance by DUS. The source material does not specify surveillance intervals or a detailed post-revascularisation imaging schedule.

Follow-up should incorporate:

• neurological symptom review;

• reassessment of cardiovascular risk factors;

• lipid and diabetes monitoring;

• renal and other laboratory assessment when clinically indicated;

• adherence to preventive treatment;

• repeat carotid DUS when surveillance is being used or when disease progression is suspected.

The choice between continued medical treatment and revascularisation should be revisited if the patient develops new neurological symptoms, demonstrates stenosis progression, develops high-risk plaque features, or experiences changes in procedural risk or life expectancy.