Ultrasound Could Detect Potential Heart Attacks, Stroke Before Symptoms
A study of portable ultrasound carried out in the United States, Canada, and India demonstrated the potential of this technology for detecting plaques in peripheral arteries that can lead to heart attacks and stroke before symptoms arise, in both developed and developing country settings, allowing preventive treatment in those affected. The study was published in the December 2014 edition of Global Heart, the journal of the World Heart Federation.
In this study, atherosclerotic cardiovascular disease (ASCVD) was determined using ultrasound of both the carotid arteries and the ileofemoral arteries. The findings were summarized in index called the Fuster-Narula 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 relatively young (mean age 44 years, 34% female) asymptomatic volunteers recruited from the semiurban 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 (eg, smoking cessation, no alcohol, vegetarian diet, physically active lifestyles, daily meditation). Radiology resident doctors with no prior training in vascular ultrasound were trained on the spot to perform the ultrasound examinations.
To compare the imaging findings with traditional risk factors, two cohorts (481 people) were recruited from primary care clinics in North America (one in Richmond, Texas, the other in Toronto, Ontario, Canada). Along with the same ultrasound examinations given in the Indian cohort, comprehensive ASCVD risk factor data were gathered 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. In most cases, the North American subjects were visiting clinics for routine health examinations. Effectiveness of established ASCVD prevention guidelines was then compared with results from direct imaging and trained experts performed ultrasound at each location.
In India, ultrasound revealed plaques in at least one artery in almost one-quarter (24%) of those examined; 107 (11%) had plaques in only the carotid arteries, 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 subjects 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 semiurban populations, although 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 ATP III guidelines, the most widely used guidelines. Using the recently published, more stringent ATP IV guidelines, 67 individuals (one-third of those with plaque and 14% of the total US/Canadian cohort) with carotid plaque would also have failed to qualify for treatment.
In addition, the study revealed 34 people in the US/Canadian setting 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 evident).
The authors wrote: "Our study shows that automation in ultrasound imaging technology allows even nonexpert users to rapidly evaluate the presence of subclinical atherosclerosis in a large population. Detection of subclinical atherosclerosis is further enhanced by inclusion of the iliofemoral artery examination."
In a linked comment published with this paper, Tasneem Z. Naqvi, MD, a professor of medicine at the Mayo College of Medicine and Division of Cardiology in Scottsdale, Arizona, adds: "This study shows that the assessment of subclinical atherosclerosis by a portable, user-friendly bedside tool is feasible in large populations and the technique of carotid ultrasound imaging and IMT assessment could be adopted by novices after an eight-hour crash course."
Naqvi concludes: "The study by Bedi et al puts into perspective the weakness of a risk factor-based approach to identify individuals with subclinical atherosclerosis who are more likely to develop future cardiovascular events. The study shows that the vascular ultrasound imaging technology is ripe and that the previously existing barriers such as poor resolution, cumbersome protocols, need for off-line processing and need for expert performers no longer exist. The question that this study does not address, and perhaps no study in the future might, is whether this imaging-based approach would save more lives than the risk-based approach. We need to ponder if treating nearly 50% of the adults with statins with a risk scoring algorithm (as happens in the US) is more appropriate vs treating only those who have subclinical atherosclerosis based on a comprehensive and readily available, cheap and simple screening method. This study makes a compelling argument in favor of imaging for screening."
— SOURCE: World Heart Federation