While the clinical use of bioimaging tests for subclinical atherosclerosis remains a topic of debate, coronary artery calcium (CAC) score is a better predictor of subsequent cardiovascular disease events than carotid intima-media thickness (IMT), according to a study published in the June 23 issue of Archives of Internal Medicine.
Aaron R. Folsom, MD, from the School of Public Health in the University of Minnesota in Minneapolis, and colleagues conducted a prospective cohort study of 6,698 subjects aged 45 to 84 years in four ethnic groups, who were initially free of cardiovascular disease (CVD), with standardized carotid IMT and CAC measures at baseline. The subjects were pooled from six field centers of the Multi-Ethnic Study of Atherosclerosis (MESA).
The authors wrote that the main outcome measure was the risk of incident CVD events (coronary heart disease, stroke and fatal CVD) over a maximum follow-up of 5.3 years.
The researchers found that there were 222 CVD events during follow-up; CAC was associated more strongly than carotid IMT with the risk of incident CVD.
After adjustment for each other (CAC score and IMT) and traditional CVD risk factors, the investigators said that the hazard ratio of CVD increased 2.1-fold for each 1-standard deviation (SD) increment of log-transformed CAC score versus 1.3-fold for each 1-SD increment of the maximum IMT.
For coronary heart disease, Folsom and colleagues found that the hazard ratios per 1-SD increment increased 2.5-fold CAC score and 1.2-fold for IMT. The authors wrote that the receiver operating characteristic curve analysis also suggested that CAC score was a better predictor of incident CVD than was IMT, with areas under the curve of 0.81 vs. 0.78, respectively.
The investigators noted that the limitations included a relatively short follow-up period and a relatively small number of strokes to date, especially as the population ages and the ratio of strokes to coronary heart disease events increases.