Femoral Ultrasound Shows Promise for Atherosclerosis Screening, Risk Assessment

Imaging the femoral arteries may provide clinicians with a simpler way of assessing patients’ future risk of cardiovascular disease, a new study suggests. 

Compared with atherosclerotic plaques located in the carotid arteries, those in the femoral arteries showed a stronger correlation with some of the most common risk factors for cardiovascular disease. Femoral plaques also showed a better ability to predict a positive coronary artery calcium (CAC) score.

“Assessment of femoral plaques with vascular ultrasound is an appealing strategy for predicting future coronary events and a potential tool for improving patient stratification to achieve more efficient primary prevention,” write Martín Laclaustra, MD, PhD (St. Louis University-Madrid, Madrid, Spain), and colleagues in a Journal of the American College of Cardiology paper published early online today ahead of the March 22, 2016, issue.

The researchers drew on data from a unique repository—the longitudinal Aragon Workers’ Health Study (AWHS)—which began in 2009 and follows the health of thousands of workers in an automobile assembly plant located in Spain. Although women are followed in the main study, they were not included in the present analysis due to small numbers. Therefore, the imaging study consisted of 1,423 middle-aged men who underwent carotid, femoral, and abdominal ultrasound, CAC scoring, and measurement of ankle-arm blood pressure index, in addition to physical exam and blood and urine collection.

Plaques Prevalent, Strongly Predictive in Middle Age

Overall, 72% of participants had subclinical atherosclerosis, which was defined as the presence of any plaque in the carotid or femoral arteries and/or a CAC score of ≥ 1. Ultrasound alone detected plaques in 65%. Among plaques detected by ultrasound, 54% were in the femoral arteries versus 34% in the carotids. Additionally, 38% of those with subclinical atherosclerosis had a positive CAC score, with femoral plaques showing stronger ability to predict a positive score than carotid plaques.

Having subclinical atherosclerosis was associated with higher prevalence, higher values, and higher number of known traditional risk factors for cardiovascular disease including cholesterol, smoking, and hypertension. Of those, current smoking was most strongly associated with plaques in the femoral and carotid arteries.

For a typical 50-year-old man with three or more traditional risk factors, the prevalence of subclinical atherosclerosis in any vascular territory was nearly 92%. Across all risk factors from 0 through 3 or more, however, more subclinical atherosclerosis was located in the femoral artery than any other territory.

Valuable Addition to Risk Estimation

Although visualization of carotid plaque on imaging has shown promise as a means of assessing risk factors, current guidelines do not recommend carotid screening for cardiovascular disease risk prediction, Laclaustra and colleagues note. Nevertheless, they say their analysis suggests that risk estimation “can be significantly improved by considering the presence of carotid and/or femoral plaques, especially the presence of femoral plaques.”

Among the findings the researchers considered most striking is that subclinical atherosclerosis was present in 56.8% of participants considered to be at low risk. The strength of the association between early atherosclerosis and characteristics not considered in standard risk scales raises the possibility that at-risk patients are being missed. “We propose that patients presenting with subclinical atherosclerosis, despite being classified at low risk, will be more likely to develop clinical events,” they suggest.

Laclaustra and colleagues also speculate that their finding that carotid atherosclerosis was less strongly correlated with traditional risk factors than femoral atherosclerosis raises the possibility that it is also less useful as a predictive marker.

Potential Motivation for Lifestyle Changes

Among the advantages of ultrasound screening are that it is relatively inexpensive and does not require radiation, say Andrew Nicolaides, MS (Imperial College, London, United Kingdom), and Andrie G. Panayiotou, MSc, PhD (Cyprus University of Technology, Cyprus, Greece), in an editorial accompanying the study. Once identified, plaques can be followed to see if they are progressing or regressing. But perhaps most important of all, such screening could prove to be a potent form of motivation for lifestyle modification since “there is nothing more powerful than asymptomatic individuals experiencing a real-time image of their arteries showing atherosclerotic deposits,” they write.

Speaking with TCTMD, study investigator and JACC Editor-in-Chief Valentin Fuster, MD, PhD (Mount Sinai School of Medicine, New York, NY), said he hopes that is the case.

“We adults don’t change our behaviors that easily,” he said, adding that his group is currently conducting a study in 4,000 people to try to narrow down which intervention type—individual or group therapy—is more effective at affecting a change. “We’ll see what happens,” Fuster noted.

Nicolaides and Panayiotou caution that the practice guideline panel will likely want to scrutinize this issue further, and cost-effectiveness studies will be necessary before population screening can be recommended. However, they assert that the study authors have created a “rational plan” for incorporating this type of assessment that can include repeated follow-up scans, additional screening and risk-factor modification depending on the findings of a simple, non-invasive ultrasound.

Fuster said he believes the results of the study will eventually impact guidelines. As for the cost aspect, he said the ultrasound used in the study is not yet available, although it will be soon. Importantly, it is expected to be fairly economical so that widespread femoral artery screening can be a reality.

“This study is interesting, because it is an open door [showing] that maybe in the future we should identify who has the disease only with ultrasound of the femoral artery and maybe this will be sufficient to really change a person’s lifestyle,” Fuster concluded. 

Sources:

• Laclaustra M, Casasnovas JA, Fernández-Ortiz A, et al. Femoral and carotid subclinical atherosclerosis association with risk factors and coronary calcium: the AWHS study. J Am Coll Cardiol. 2016;67:1263-1274. 
• Nicolaides A, Panayiotou AG. Screening for atherosclerotic cardiovascular risk using ultrasound. J Am Coll Cardiol. 2016;67:1275-1277. 

Disclosures:

• The study was funded by the Instituto Aragonés de Ciencias de la Salud and the Spanish National Center for Cardiovascular Diseases.  
• Laclaustra was supported in part by grants from the Instituto de Salud Carlos III, which includes Fonds Européen de Développement Économique et Régional (FEDER) funding. 
• Nicolaides, Panayiotou, and Fuster report no relevant conflicts of interest. 

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