Abstract 3405: Thoracic Aortic Calcium vs. Coronary Artery Calcium for the Prediction of Coronary Heart Disease and Cardiovascular Events
Background: Coronary artery calcium (CAC) measured by computed tomography (CT) independently predicts coronary heart disease (CHD) and cardiovascular disease (CVD) events. We investigated whether thoracic aortic calcium (TAC), also measured by the cardiac CT, predicts events, and is additive over Framingham risk score (FRS) and CAC.
Methods: 1484 asymptomatic adults (mean age 55 years, 40% female) with CT scans were followed for an average of 4.7 years for hard CHD (myocardial infarction and CHD death) and total CVD (hard CHD plus late revascularization and stroke) events. Cox regression examined the relation of CAC and TAC to event risk. Receiver operator characteristic (ROC) curves examined if CAC and TAC contributed to prediction of events over FRS, and if TAC provided additional prediction over FRS and CAC.
Results: Overall, 61% of subjects had CAC scores of <10, 19% 10–99, 20% 100+. For TAC, proportions were 75%, 11%, and 13%, respectively. 16 hard CHD events and 34 total CVD events occurred. The incidence of CHD events increased across CAC score groups (from 0.2 to 4.1% for hard and 0.3% to 7.8% for total CHD events, p-trend<0.0001 for both) and TAC score groups (from 0.7% to 2.1% for hard, p-trend=0.03 and 1.5% to 5.1% for total CHD events, p-trend<0.001). The table⇓ below shows FRS-adjusted hazard ratios (HRs) for the prediction of CHD and CVD events by CAC and TAC score category (<10, 10–99, and 100+).
Conclusion: Increasing CAC, but not TAC predicted both CHD and CVD events independent of FRS. Importantly, TAC did not improve prediction of CHD and CVD events over information provided by CAC, suggesting TAC not to be useful for cardiac risk assessment.