1. JACC Cardiovasc Imaging. 2009 Mar;2(3):319-26.

Thoracic aortic calcium versus coronary artery calcium for the prediction of
coronary heart disease and cardiovascular disease events.

Wong ND, Gransar H, Shaw L, Polk D, Moon JH, Miranda-Peats R, Hayes SW, Thomson
LE, Rozanski A, Friedman JD, Berman DS.

Division of Cardiology, University of California, Irvine, California, USA.

OBJECTIVES: This study compared the ability of coronary artery calcium (CAC) and 
thoracic aortic calcium (TAC) to predict coronary heart disease (CHD) and
cardiovascular disease (CVD) events. BACKGROUND: Coronary artery calcium has been
shown to strongly predict CHD and CVD events, but it is unknown whether TAC, also
measured within a single cardiac computed tomography (CT) scan, is of further
value in predicting events. METHODS: A total of 2,303 asymptomatic adults (mean
age 55.7 years, 38% female) with CT scans were followed up for 4.4 years for CHD 
(myocardial infarction, cardiac death, or late revascularizations) and CVD (CHD
plus stroke). Cox regression, adjusted for Framingham risk score (FRS), examined 
the relation of Agatston CAC and TAC categories, and log-transformed CAC and TAC 
with the incidence of CHD and CVD events and receiver-operator characteristic
(ROC) curves tested whether TAC improved prediction of events over CAC and FRS.
RESULTS: A total of 53% of subjects had Agatston CAC scores of 0; 8% 1 to 9; 19% 
10 to 99; 12% 100 to 399; and 8% > or =400. For TAC, proportions were 69%, 5%,
12%, 8%, and 7%, respectively; 41 subjects (1.8%) experienced CHD and 47 (2.0%)
CVD events. The FRS-adjusted hazard ratios (HR) across increasing CAC groups
(relative to <10) ranged from 3.7 (p = 0.04) to 19.6 (p < 0.001) for CHD and from
2.8 (p = 0.07) to 13.1 (p < 0.001) for CVD events; only TAC scores of 100 to 399 
predicted CHD and CVD (HR: 3.0, p = 0.008, and HR: 2.3, p = 0.04, respectively); 
these risks were attenuated after accounting for CAC. Findings were consistent
when using log-transformed CAC and TAC Agatston and volume scores. The ROC curve 
analyses showed CAC predicted CHD and CVD events over FRS alone (p < 0.01);
however, TAC did not further add to predicting events over FRS or CAC.
CONCLUSIONS: This study found that CAC, but not TAC, is strongly related to CHD
and CVD events. Moreover, TAC does not further improve event prediction over CAC.

PMID: 19356578 [PubMed - indexed for MEDLINE]