From the Guidelines
When assessing for internal carotid artery (ICA) stenosis, it is crucial to evaluate both clinical symptoms and risk factors, and consider carotid duplex ultrasonography as the initial screening test, followed by CT angiography or MR angiography for detailed anatomical visualization, as recommended by the most recent guidelines 1.
Clinical Evaluation
When assessing for ICA stenosis, look for transient ischemic attacks, amaurosis fugax, stroke symptoms, and carotid bruits on physical examination. Risk factors to assess include hypertension, diabetes, smoking, hyperlipidemia, advanced age, and family history of cardiovascular disease.
Diagnostic Evaluation
Diagnostic evaluation should include:
- Carotid duplex ultrasonography as the initial screening test, which measures blood flow velocity and provides stenosis percentage.
- For patients with positive findings, consider CT angiography or MR angiography for detailed anatomical visualization.
- Digital subtraction angiography remains the gold standard but is typically reserved for cases requiring intervention.
Laboratory Tests and Management
Laboratory tests should include lipid profile, blood glucose, and HbA1c. The degree of stenosis is critical for management decisions, with severe stenosis (>70%) often warranting intervention, while moderate stenosis (50-69%) may require intervention in symptomatic patients, as suggested by recent guidelines 1. Assessment should also include evaluation of collateral circulation and plaque characteristics such as ulceration or hemorrhage, as unstable plaques pose higher stroke risk regardless of stenosis percentage.
Recent Guidelines
Recent guidelines from the European Society of Cardiology 1 recommend that symptomatic ICA stenosis patients be assessed by a vascular team including a neurologist, and that dual antiplatelet therapy (DAPT) is recommended in the early phase of minor strokes in patients with ICA stenosis, if not revascularized, for at least 21 days, considering the bleeding risk. Long-term treatment with single antiplatelet therapy (SAPT) should be considered following ICA revascularization.
From the Research
Assessment of ICA Stenosis
To assess internal carotid artery (ICA) stenosis, several factors should be considered:
- Peak-systolic velocity (PSV) of ≥ 180 cm/sec as a single parameter or requiring the ICA/common carotid artery (CCA) PSV ratio ≥ 2.0 in addition to PSV of ≥ 125 cm/sec for laboratories using the Society of Radiologists in Ultrasound in 2003 (SRUCC) criteria 2
- Degree of stenosis, with severe stenosis defined as ≥ 70% 2, 3
- Presence of collateral flows using transcranial Doppler (TCD) to evaluate the hemodynamic significance of high-grade ICA stenosis 4
- Magnetic resonance angiography (MRA) to confirm the degree of stenosis 4
Diagnostic Criteria
Diagnostic criteria for ICA stenosis include:
- PSV of ≥ 125 cm/sec as the primary SRUCC parameter for ≥ 50% ICA stenosis, although this may not meet prespecified thresholds for adequate sensitivity, specificity, and accuracy 2
- ICA/CCA PSV ratio ≥ 2.0 as an additional parameter to improve the accuracy of carotid duplex examinations 2
- Established collateral flow as an indicator of hemodynamic significant ICA stenosis 4
Limitations and Considerations
Limitations and considerations in assessing ICA stenosis include:
- Overestimation of degree of stenosis for both moderate (50-69%) and severe (≥ 70%) ICA lesions using SRUCC criteria 2
- Uncertainty in severe stenosis, where PSV may decrease due to high flow resistance or high backward pressure 4
- Need for intensive management of modifiable risk factors and dual antiplatelet therapy for secondary stroke prevention in patients with ICA stenosis 5