Relationship between coronary artery and descending thoracic aortic calcification as detected by computed tomography: the Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Cardiac computed tomography (CT) is a well-established tool for the detection of cardiovascular calcium. Coronary artery calcification (CAC) is highly sensitive for the detection of coronary artery disease (CAD) as well as predictive of future cardiovascular (CV) events. Descending thoracic aortic calcification (DTAC) is common in the elderly and its presence is also associated with increased risk of CV events. Previous studies demonstrate that DTAC is associated with obstructive CAD and coronary risk factors. However, no prior studies have examined the association of CAC and DTAC as detected by cardiac CT in a large population-based cohort. METHODS: In the Multi-Ethnic Study of Atherosclerosis, the study population included a population-based sample of four ethnic groups (Chinese, White, Hispanic and African-American) of 6814 women and men ages 45-84 years old. Participants underwent non-enhanced cardiac CT and both CAC and DTAC were quantified. DTAC was measured from the lower edge of the pulmonary artery bifurcation to the cardiac apex. Multivariable relative risk regression was used to evaluate relationships between CAC, DTAC and measured cardiovascular risk factors. RESULTS: Overall 3030 (44%) did not demonstrate any detectable CAC or DTAC. A total of 1930 (28%) had only CAC, 386 (6%) had isolated DTAC, and 1464 (22%) participants were found to have both CAC and DTAC. CAC had a higher prevalence than DTAC in men (58% vs. 45%). Participants with DTAC were older than those with CAC (mean age was 71 and 66 years old, respectively). Participants with DTAC had increased risk for the presence of CAC independent of cardiovascular risk factors (prevalence ratio [PR]: 1.17, 95% CI: 1.07-1.28). Severity of DTAC was a stronger predictor of the presence of CAC in women as compared to men (PR: 1.04, 95% CI: 1.02-1.06, and PR: 0.99, 95% CI: 0.98-1.01, respectively). CONCLUSIONS: DTAC was found to be a strong predictor of CAC independent of CV risk factors. Ongoing follow-up of this cohort will evaluate whether DTAC is an independent marker of risk for CV events.