Aortic calcification closely correlated with CVD risk factors
MedWire News: Calcification in the abdominal aorta (AAC) is a stronger correlate of cardiovascular disease (CVD) risk factors than is calcification in the coronary arteries (CAC), clinical data indicate.
However, the study authors admit that the value of AAC as compared with CAC for predicting cardiovascular events remains to be evaluated.
Michael Criqui (University of California, San Diego, USA) and co-workers analyzed data from the Multiethnic Study of Atherosclerosis. This was a prospective cohort study investigating subclinical atherosclerosis in 6815 individuals aged 45-84 years without vascular disease at baseline.
As part of an imaging substudy, 1974 participants underwent computed tomography scanning to measure AAC and CAC. This revealed no calcification whatsoever in 21.1% of the cohort; aortic calcification only in 21.1%; coronary calcification only in 7.7%; and both aortic and coronary calcification in 50.5%.
Each participant was assigned an Agatston score to reflect their overall burden of vascular calcium; these scores were then analyzed with reference to the distribution of cardiovascular risk factors.
Writing in the journal Arteriosclerosis, Thrombosis, and Vascular Biology, Criqui's team reports that Agatston scores for AAC were much higher than those for CAC, "such that the 50th percentile for AAC and 90th percentile for CAC were similar."
AAC showed a positive correlation with age, past/current smoking, low-density lipoprotein cholesterol, systolic blood pressure, and use of lipid-lowering or antihypertensive drugs, and an inverse correlation with Black and Hispanic ethnicity and high-density lipoprotein cholesterol.
CAC was positively associated with age, ethnicity, systolic blood pressure, and use of antihypertensive medication. CAC was also strongly associated with male gender, whereas AAC did not show any gender association. Unlike AAC, CAC was not significantly associated with smoking, high- or low-density lipoprotein cholesterol, or with use of lipid-lowering drugs.
Finally, receiver operating characteristic curves revealed that AAC was a stronger predictor for presence of CVD risk factors than was CAC, with C-statistics of 0.859 and 0.794, respectively.
The investigators note that both AAC and CAC were highly prevalent in this cohort of people without known vascular disease, and say their major finding was "a stronger association of most standard CVD risk factors with AAC compared with CAC."
They conclude: "Further analyses in this cohort will explore the quantitative association by computed tomography of AAC with future CVD events, taking into account the CAC, to determine whether AAC predicts events independently of the CAC burden."
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By Joanna Lyford