A study of portable ultrasound performed in the United States, Canada, and India has revealed the potential of this technology for identifying plaques in peripheral arteries that can lead to heart attacks and stroke before symptoms occur, in both developed and developing country environments, allowing preventive treatment in those affected.
The study was conducted by Dr. Ram Bedi, affiliate assistant professor, department of bioengineering, University of Washington (Seattle, WA, USA), and Prof. Jagat Narula, editor-in-chief of Global Heart and Icahn School of Medicine at Mount Sinai (New York, NY, USA), and colleagues.
Many research studies have shown that it is possible to evaluate subclinical atherosclerotic cardiovascular disease (ASCVD) using ultrasound imaging. Because more portable and lower cost ultrasound devices are now available, combined with increased automation and enhancements, it may be possible in the near future to typically examine people with ultrasound to establish any ASCVD present before symptoms arise, so that future disease can be prevented, for example using medication. In this study, ASCVD was determined using ultrasound of both the carotid arteries and the ileofemoral arteries. The findings were summarized in an easy to understand index called the Fuster-Narula (FUN) Score.
Data were gathered from four cohorts, two Indian and two North American. In India, a medical camp setting was used, and screening with automated ultrasound imaging was conducted over eight days in 941 comparatively young (mean age 44 years, 34% female) asymptomatic volunteers recruited from the semi-urban town of Sirsa (Haryana) and urban city of Jaipur (Rajasthan) in northern India. The cohort from Sirsa was specifically recruited because all participants had already undergone aggressive lifestyle changes (smoking cessation, no alcohol, vegetarian diet, physically active lifestyles, daily meditation), radiology resident physicians who had no earlier training in vascular ultrasound were trained right on the spot to perform the ultrasound examinations.
To compare the imaging findings with traditional risk factors, two cohorts (481 persons) were recruited from primary care clinics in North America (one in Richmond, TX, USA, the other in Toronto, Canada). As well as the same ultrasound examinations given in the Indian cohort, comprehensive ASCVD risk factor information collected from these participants, all of whom were self-referred asymptomatic individuals (mean age 60 years, 39% female). Data collected included cholesterol levels, blood pressure, glucose level, weight, height, smoking and family history. These people were attending clinics for routine health examinations in most cases. Effectiveness of established ASCVD prevention guidelines was then compared to findings from direct imaging; ultrasound was performed by trained experts at each center.
In India, ultrasound revealed plaques in at least one artery in almost a quarter (24%) of those examined; 107 (11%) had plaques in only the carotids, 70 (7%) in both the carotids and iliofemoral arteries, and 47 (5%) had plaques in only the iliofemoral arteries. If just the carotids had been examined, 177 (19%) of the asymptomatic individuals would have been identified with plaques; by adding the iliofemoral examination, 47 additional individuals (5% of the total) were identified with plaque. Older age and male sex were associated with the presence of plaque both in urban and semi-urban populations (the much higher levels of smoking in men could account for their higher risk).
Data from the American and Canadian clinics showed that 203 subjects (42%) had carotid plaque; 166 of these (82% of those with plaque) would not have qualified for lipid-lowering therapy such as statins under the most widely used guidelines known as ATP III (Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults [Adult Treatment Panel]) guidelines. Using the recently published, more rigid ATP IV guidelines, 67 people (one-third of those with plaque and 14% of the total US/Canadian cohort) individuals with carotid plaque would also have failed to qualify for treatment.
Furthermore, the study revealed 34 individuals in the United States and Canada who qualified for treatment under ATP III but did not have any plaques, and this number increased to 81 under ATP IV (if receiving treatment such as statins, these people could be said to be overtreated, since no plaques were seen).
The investigators reported,