More and more offices are performing their own carotid ultrasounds. In light of recent guidelines published by the U.S. Preventive Services Task Force (USPSTF), who should have carotid imaging to detect stenosis? Please discuss patients with transient ischemic attack (TIA) or cerebrovascular accident, patients with no symptoms but a bruit, high-risk patients with cardiac disease or peripheral arterial disease, diabetic patients, and those who simply request screening for peace of mind.
—Karl Heymann, MD, Red Hook, N.Y.
Not only are patients being screened in doctors’ offices, but companies are marketing “stroke screening packages,” including carotid ultrasound, for as little as $139. Patients are enticed by misleading claims of benefit and overly inclusive criteria for who should be tested. I answered the “risk assessment” for one of these companies and discovered that I am “at risk for carotid artery disease” and should “consider contacting [their company] to schedule a stroke/ carotid artery screening and/or a peripheral arterial disease screening.” Why? Because I exercise <20-30 minutes three times a week and have a family history of coronary artery disease (even though I am a 36-year-old woman with no other risk factors). It’s a good thing I know better.
So who should be screened for carotid artery stenosis? Let’s start with who should not be screened. A patient without symptoms should not have a carotid duplex ultrasound for “peace of mind” based on the 2007 USPSTF recommendations against screening the general population for asymptomatic carotid artery stenosis. This evidence-based review of the literature gave screening of asymptomatic patients a grade D recommendation (“Do not screen”). The task force noted that the benefit of screening is limited by a low prevalence of treatable disease and that ultrasound can lead to false positives with resultant morbidity and mortality from further confirmatory testing and unnecessary carotid endarterectomies (Ann Intern Med. 2007; 147:860-870). Patients presenting with stroke or TIA, on the other hand, should certainly be evaluated for carotid stenosis since they are, by definition, symptomatic. Whether patients with risk factors for vascular disease, such as those noted in the question, but no symptoms should be screened is more controversial. Unfortunately, there is no single risk factor or clinically useful risk stratification tool to identify high-risk patients, and for that reason, the USPSTF recommends against screening. Other organizations, such as the Society for Vascular Surgery and the American Society for Neuroimaging, have more liberal recommendations and suggest that screening be considered for older patients with vascular risk factors, such as smoking, hypertension, diabetes, and hyperlipidemia. In addition, although the most recent USPSTF recommendations do not directly address the question of screening patients with carotid bruits, some experts recommend carotid ultrasound for these patients, since they are at a higher risk of ipsilateral stroke. It may be worth having a discussion regarding the risks and benefits of screening with asymptomatic patients who have vascular risk factors, however, as there are no prospective trials looking at the impact screening and revascularization may provide these subgroups.
—Susan Kashaf, MD, MPH (124-12)
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