Amer Johri, MD, FASE, MSc, FRCPC

Your 45-year-old asymptomatic patient comes to your clinic with a commercial screening result in-hand, demonstrating moderate carotid artery disease. What do you do?

This is an increasingly common scenario faced by physicians with the advent of private, for-profit vascular screening tests now available as a non-referred service to patients. Patients subscribing to these services are typically given a printout describing the result of screening tests such as echocardiograms, carotid ultrasound screen, and ankle brachial index, and are then instructed to discuss the results with their physicians. The physician is left with the conundrum of dealing with a test result he did not order in an asymptomatic patient. A reasonable approach would include: assessing the quality of the screening test; determining the patient’s motivation or concern for obtaining the test in the first place; determining the need for a further formal test (such as a full carotid ultrasound following the ASE guidelines ); identifying other cardiac risk factors such as diabetes, hypertension, family history; and consideration of established treatment guidelines for asymptomatic vascular disease (statin therapy, smoking cessation, blood pressure control, aspirin therapy, exercise, glucose control, influenza vaccination). However, there remains the controversy of whether screening for asymptomatic disease in the first place has any benefit at all.

The US Preventive Services Task Force (USPTSF) recommends AGAINST routine screening for peripheral arterial disease and carotid artery stenosis. But does this contradict the emerging emphasis on primary prevention, early assessment of ‘vascular age’, and perhaps even the concept of primordial prevention? The USPTSF recommendation against screening comes from an older definition of appropriate intervention for asymptomatic individuals. At the time, the task force assumed carotid endarterectomy was the only intervention applicable to asymptomatic carotid artery stenosis. The critical issue of identifying subclinical atherosclerosis was overlooked in their cost equation. It is now generally accepted that identification of early atherosclerotic vascular disease, before symptoms, can lead to lifestyle modification and consideration of therapy.

The USPTSF recommendation considered surgery as the only intervention available for treatment of carotid atherosclerosis, an approach which is not consistent with medical practice and likely explains the lack of benefit observed in their cost model. A true cost model, taking into consideration the benefit of identifying subclinical vascular disease early and treating with medical management, has not been developed. As we are at equipoise, it seems reasonable that the cost of nontargeted initial screening be absorbed by the participant at the present time. In patients found to have significant disease, further downstream confirmatory testing and management should be guided by clinicians and viewed as an opportunity to alter the trajectory of atherosclerotic disease. The patient will benefit from open communication. We really don’t know whether everyone should be screened in a non-targeted manner, or whether this is even financially sensible.

One of the greatest concerns raised by opponents of nontargeted vascular screening is that, although the initial screen can be done at a low cost privately (approximately $45), we may not be able to sustain the costs of downstream imaging and testing; is this the tip of the iceberg? On the other hand, proponents believe that carotid screening and other imaging biomarkers represent a paradigm shift towards ‘treating arteries, not risk factors’. The rationale is that risk calculators may only identify a fraction of patients that will experience cardiovascular events. Observational data from prevention clinics show that once carotid plaque is routinely quantified, rates of atherosclerosis regression significantly increase with a reduction of outcomes. Identification of carotid atherosclerosis by ultrasound can change behaviors, not only of patients but also physicians. It has been shown that showing smokers ultrasound images of their plaques significant increased rates of cessation. Others have shown that vascular screening significantly increased prescriptions for both hypertension and hyperlipidemia.

Currently the main driver for vascular screening outside of prevention clinics has been a demand from patients. Vascular screening is generally safe and empowers the patient to better understand cardiovascular risk or lack thereof. A carotid screen can identify patients who have significant carotid plaque which can be confirmed by a formal study. This would re-stratify an otherwise asymptomatic patient into a higher risk one with established atherosclerotic disease. The presence of carotid atherosclerosis has been shown to be associated with cardiovascular outcomes in recent large meta-analysis. The 2011 ACC/AHA guideline update refers to this growing body of literature, confirming that in patients with atherosclerotic vascular disease, intensive risk-reduction therapies improve a variety of outcomes including survival, recurrent events, the need for revascularization, and quality of life. Similarly, the new 2013 ACC/AHA guideline update can be interpreted to recommend high-intensity statin therapy if peripheral arterial disease of atherosclerotic origin is established.

Thus vascular testing such as carotid ultrasound has emerged as a tool used by prevention experts and as a screening test demanded by patients. Over 2.7 million cardiovascular screening tests were done by one private company alone between 2005 and 2008. While recognizing the benefit and need for determining vascular age/disease, we also need to be cognizant of possible aggressive marketing creating a demand. The best approach lies somewhere in between, and as part of the imaging community we must better understand the limitations of this tool and be open to discussing this controversial topic further. The ASE Vascular Council continues to develop resources and educational sessions for our membership to better understand performance, interpretation, and quality assurance of ultrasound based vascular testing.

Dr. Amer M. Johri is a cardiologist and echocardiographer with clinical and research interest in carotid ultrasound Imaging. He has neither an affiliation nor financial relationship with any screening company. Dr. Johri posts cardiovascular related tweets at @amerjohri.