To Check or Not to Check? Carotid Screening Should be Limited to Highly Selected Patients, Say Experts

Hollywood, FL—Two experts took the stage yesterday at the International Symposium on Endovascular Therapy (ISET) 2016 to debate the merits of carotid screening, coming to the conclusion that despite the somewhat tepid support from clinical guidelines, there is still a benefit to screening certain patients.

During the ISET debate, Laurence Needleman, MD, of Thomas Jefferson University Hospital (Philadelphia, PA), spoke in support of carotid screening, but said it should be performed only in appropriate patient populations by appropriate personnel following appropriate criteria.

“There’s a lot of direct-to-patient advertising that occurs from screening organizations that are generally for profit,” Needleman told TCTMD after the session. “They take an unselected group of patients—patients just come with money and choose to be screened. They might have massive risk factors, they might have no risk factors, or they might even be younger than recommended.”

Presently, a broad coalition of professional societies, including the American Stroke Association (ASA), American College of Cardiology (ACC), and American Heart Association (AHA), among others, state that carotid duplex ultrasound is not recommended for routine screening of asymptomatic patients who have no clinical manifestations of atherosclerosis or atherosclerotic risk factors (class III, level of evidence C). In a broad group of unselected patients, there is no benefit to carotid screening, agreed Needleman. While there are rare instances where screening identifies carotid stenosis, these patients are the minority and testing has very limited use in this group.

The ASA, ACC, AHA, and others say duplex ultrasonography might be considered to detect carotid stenosis in asymptomatic patients without clinical evidence of atherosclerosis but who have at least 2 or more risk factors, such as hypertension, hyperlipidemia, or a family history of early atherosclerosis or stroke. However, the professional societies also state that it is unclear whether establishing a diagnosis of carotid disease would justify taking clinical steps that affect clinical outcomes.

Two other groups—the Society of Vascular Surgeons (SVS) and the American Society of Echocardiography (ASE)—say that carotid ultrasound to identify carotid plaque can be useful in certain patients. The SVS suggests individuals with cardiovascular risk factors might benefit from preventive screening for vascular disease with noninvasive testing, while the ASE task force states that measuring and identifying carotid plaque can be useful for refining cardiovascular disease risk in patients considered intermediate risk, such as those with a 6% to 20% risk of clinical events in 10 years. However, the ASE also states that testing should not be done unless the results would be expected to change therapy.

While there is a consensus that carotid screening should not be applied in asymptomatic individuals, screening intermediate-risk patients, particularly if there is concern about how aggressively to treat, is also controversial, said Needleman. “In that group, generally, many of the vascular societies say there is some value to it, but the proof that this actually affects outcomes is not there. It’s a belief but it’s far from proven, because it would require huge amounts of money and a large number of patients,” he told TCTMD.

The Case Against Routine Screening

Speaking during the ISET debate, Thom Rooke, MD, of the Mayo Clinic (Rochester, MN), strengthened the case against routine carotid screening. Screening, he said, is checking patients for disease when there are no signs, symptoms, laboratory or radiological evidence, or personal history of disease. Despite this, screening is done “all the time,” such as routine screening for prostate or breast cancer. The question is whether physicians should also be routinely screening for carotid disease.

“I would argue that we should only screen when 3 criteria can be met,” said Rooke. These criteria, which Rooke phrased in the form of questions to the audience, include the following:

• Can the silent disease be detected early through screening?
• Is there is an available therapy for the identified disease?
• Does early treatment lead to improved outcomes?

On the first 2 fronts, Rooke said carotid screening meets the mark, but like Needleman, he said no studies have shown that intervening early affects clinical outcomes. He noted that the United States Preventive Services Task Force (USPSTF) has come out firmly against screening for asymptomatic carotid artery stenosis in the general adult population, because the group believes only a small proportion of disabling unheralded strokes are caused by carotid stenosis. The USPSTF has previously stated that more than 4,000 patients would need to be screened to prevent 1 stroke.

“Is carotid screening something that should be done,” asked Rooke. “The answer is no. We shouldn’t be screening in the general population of asymptomatic patients, but I suppose it’s OK to screen selectively in certain high-risk populations. But as I’ve said before, is it really screening when you’re looking at people who have known coronary disease or peripheral artery disease?”

To TCTMD, Needleman said the idea that carotid screening can alter patient behavior, an argument that has also been put forth by some advocates of coronary artery calcium screening, has no proof behind it. Changing the lifestyle habits of patients is a complicated issue, one not easily solved simply “by seeing the disease in front of you,” said Needleman. “There is little scientific evidence that is true,” he added. “I’m sure there are many people deeply affected by it, but change is very difficult and very difficult to prove.”  

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 View ISET 2016 Slides