Comparing coronary artery calcium and thoracic aorta calcium for prediction of all-cause mortality and cardiovascular events on low-dose non-gated computed tomography in a high-risk population of heavy smokers.
BACKGROUND
Coronary artery calcium (CAC) and thoracic aorta calcium (TAC) can be detected simultaneously on low-dose, non-gated computed tomography (CT) scans. CAC has been shown to predict cardiovascular (CVD) and coronary (CHD) events. A comparable association between TAC and CVD events has yet to be established, but TAC could be a more reproducible alternative to CAC in low-dose, non-gated CT. This study compared CAC and TAC as independent predictors of all-cause mortality and cardiovascular events in a population of heavy smokers using low-dose, non-gated CT.


METHODS
Within the NELSON study, a population-based lung cancer screening trial, the CT screen group consisted of 7557 heavy smokers aged 50-75 years. Using a case-cohort study design, CAC and TAC scores were calculated in a total of 958 asymptomatic subjects who were followed up for all-cause death, and CVD, CHD and non-cardiac events (stroke, aortic aneurysm, peripheral arterial occlusive disease). We used Cox proportional-hazard regression to compute hazard ratios (HRs) with adjustment for traditional cardiovascular risk factors.


RESULTS
A close association between the prevalence of TAC and increasing levels of CAC was established (p<0.001). Increasing CAC and TAC risk categories were associated with all-cause mortality (p for trend=0.01 and 0.001, respectively) and CVD events (p for trend <0.001 and 0.03, respectively). Compared with the lowest quartile (reference category), multivariate-adjusted HRs across categories of CAC were higher (all-cause mortality, HR: 9.13 for highest quartile; CVD events, HR: 4.46 for highest quartile) than of TAC scores (HR: 5.45 and HR: 2.25, respectively). However, TAC is associated with non-coronary events (HR: 4.69 for highest quartile, p for trend=0.01) and CAC was not (HR: 3.06 for highest quartile, p for trend=0.40).


CONCLUSIONS
CAC was found to be a stronger predictor than TAC of all-cause mortality and CVD events in a high-risk population of heavy smokers scored on low-dose, non-gated CT. TAC, however, is stronger associated with non-cardiac events than CAC and could prove to be a preferred marker for these events.
Jacobs
Peter C
PC
Julius Center for Health Sciences and Primary Care, Department of Radiology, University Medical Center Utrecht, Netherlands. p.c.a.jacobs@umcutrecht.nl
Prokop
Mathias
M
van der Graaf
Yolanda
Y
Gondrie
Martijn J
MJ
Janssen
Kristel J
KJ
de Koning
Harry J
HJ
Isgum
Ivana
I
van Klaveren
Rob J
RJ
Oudkerk
Matthijs
M
van Ginneken
Bram
B
Mali
Willem P
WP
D000368:Aged; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging / Q000378:metabolism*; D001018:Aortic Diseases; D002114:Calcinosis / Q000209:etiology*; D002118:Calcium / Q000378:metabolism*; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000401:mortality; D015331:Cohort Studies; D017023:Coronary Angiography; D003327:Coronary Disease / Q000453:epidemiology; D003331:Coronary Vessels / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D014057:Tomography, X-Ray Computed
D002118:Calcium