ABSTRACT
The rationale for identifying patients with asymptomatic carotid artery stenosis (CAS) is the expectation that early detection and treatment (including modification of risk factors) can reduce the risk of stroke.1,2 Since these patients are by definition asymptomatic, they can only be identified through screening using various imaging modalities, particularly duplex ultrasound (DUS). As discussed in Chapter 4, screening the general population for asymptomatic CAS cannot be justified because of the low prevalence of this condition.3,4 However, the prevalence of asymptomatic CAS can be as high as 30% in high-risk groups.5,6
Although some clinicians take the position that, in the absence of reliable community-based data, it is not clear whether any group can be identified as having a high enough prevalence to make screening cost-effective,7
screening appropriate patients may provide certain benefits that are often overlooked. First, an awareness of the diagnosis may motivate patients to modify other risk factors (e.g. high blood pressure, smoking, physical inactivity). Secondly, the use of antiplatelet drugs not already part of the treatment plan for such patients may reduce stroke risk in asymptomatic individuals with CAS. No proof of such benefits currently exists, since the large, randomized trials comparing the effectiveness of interventions from the results of screening
Take-Home Messages 1. The rationale behind identification of patients with asymptomatic carotid artery stenosis (CAS) is that
early treatment may reduce the incidence of cardiovascular and cerebrovascular events. 2. Screening for asymptomatic CAS should be limited to high-risk populations to avoid unnecessary cost
and harm. 3. Duplex ultrasound should be the first choice for screening. However, clinicians should be aware of the
various scenarios where the severity of carotid disease can be under-or overestimated by this technique. 4. Contrast-enhanced magnetic resonance angiography (MRA) is a safe and accurate imaging modality for
confirmation of the diagnosis. 5. Computer tomographic angiography (CTA) is an emerging alternative to MRA, with the additional ability
to identify carotid calcifications. The disadvantages of CTA are similar to those of traditional angiography (exposure to ionizing radiation and iodinated contrast).
