Clinical Investigation
Cardiovascular Risk Assessment by Cardiovascular Ultrasound
Carotid Ultrasound Identifies High Risk Subclinical Atherosclerosis in Adults with Low Framingham Risk Scores

https://doi.org/10.1016/j.echo.2010.06.003Get rights and content

Background

Worldwide, cardiovascular (CV) disease remains the most common cause of morbidity and mortality. Although effective in predicting CV risk in select populations, the Framingham risk score (FRS) fails to identify many young individuals who experience premature CV events. Accordingly, the aim of this study was to determine the prevalence of high-risk carotid intima-media thickness (CIMT) or plaque, a marker of atherosclerosis and predictor of CV events, in young asymptomatic individuals with low and intermediate FRS (<2% annualized event rate) using the carotid ultrasound protocol recommended by the American Society of Echocardiography and the Society of Vascular Medicine.

Methods

Individuals aged ≤ 65 years not taking statins and without diabetes mellitus or histories of coronary artery disease underwent CIMT and plaque examination for primary prevention. Clinical variables including lipid values, family history of premature coronary artery disease, and FRS and subsequent pharmacotherapy recommendations were retrospectively collected for statistical analysis.

Results

Of 441 subjects (mean age, 49.7 ± 7.9 years), 184 (42%; 95% confidence interval, 37.3%-46.5%) had high-risk carotid ultrasound findings (CIMT ≥ 75th percentile adjusted for age, gender, and race or presence of plaque). Of those with the lowest FRS of ≤5% (n = 336) (mean age, 48.0 ± 7.6 years; mean FRS, 2.5 ± 1.5%), 127 (38%; 95% confidence interval, 32.6%-43.0%) had high-risk carotid ultrasound findings. For individuals with FRS ≤ 5% and high-risk carotid ultrasound findings (n = 127; mean age, 47.3 ± 8.1 years; mean FRS, 2.5 ± 1.5%), lipid-lowering therapy was recommended by their treating physicians in 77 (61%).

Conclusions

Thirty-eight percent of asymptomatic young to middle-aged individuals with FRS ≤ 5% have abnormal carotid ultrasound findings associated with increased risk for CV events. Pharmacologic therapy for CV prevention was recommended in the majority of these individuals. The lack of radiation exposure, relatively low cost, and ability to detect early-stage atherosclerosis suggest that carotid ultrasound for CIMT and plaque detection should continue to be explored as a primary tool for CV risk stratification in young to middle-aged adults with low FRS.

Section snippets

Patient Selection

Upon obtaining approval from the Mayo Clinic Institutional Review Board, the medical records of all 688 patients at our institution who underwent CIMT examinations between January 1, 2007, and December 31, 2008, were retrospectively reviewed. Clinical data were collected from the electronic medical records and an FRS was calculated for each subject. Subjects aged > 65 years, those with diabetes mellitus, those with histories of coronary artery disease, and those with incomplete clinical data

Results

Subjects (n = 441) had an average age of 49.7 ± 7.9 years, and there was a predominance of men (70%). The average FRS was 4.5 ± 4.2%. Of these subjects, 184 (42%; 95% CI, 37.3%-46.5%) had high-risk carotid ultrasound results; 90 (20%) had carotid plaque and 94 (21%) had CIMT ≥ 75th percentile for age-matched, gender-matched, and race-matched controls. The average body mass index was 27.5 ± 5.3 kg/m2, 59 subjects (13%) had family histories of premature coronary artery disease, 34 (8%) were

Discussion

Currently, traditional risk factors and the calculated FRS are the primary methods used to identify asymptomatic individuals with atherosclerosis who may benefit from more aggressive primary preventive therapy. Our principal finding is that 38% of asymptomatic young to middle-aged individuals with low FRS who are not on lipid-lowering medications have findings on carotid ultrasound examination that put them at higher risk for future adverse CV events. Our study was unique in that it included

Conclusions

Carotid ultrasound identifies a higher risk subgroup in a large percentage of asymptomatic young to middle-aged individuals with low FRS. Furthermore, pharmacologic therapy for CV prevention was recommended in the majority of these individuals. These findings, along with its lack of radiation exposure, relatively low cost, and ability to detect early-stage atherosclerosis, suggest that carotid ultrasound for CIMT and plaque detection should be further explored as a primary tool for CV risk

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