ABSTRACT

Initial developments in the field of computed tomography

(CT) provided data on the diagnostic accuracy of coronary

artery calcification (CAC). In the 2000 American College of

Cardiology (ACC) expert consensus document on CAC,

there were nearly 20 published reports on the diagnostic

sensitivity and specificity of CAC.1 Due to its ability to

directly visualize arterial plaque, it was hoped that CT-

determined CAC could more clearly define a patient’s

obstructive coronary artery disease burden, resulting in

improved diagnostic classification when compared to

ischemia tests, such as stress electrocardiography. However,

the diagnostic evidence, largely derived from selected

catheterized cohorts, revealed a markedly diminished speci-

ficity (~45%). That is, an elevated CAC score often did not

accurately signify an associated coronary stenosis. This

diminished specificity exposed both the limitations of CT-

determined CAC as a diagnostic test but also re-oriented

researchers toward a greater understanding of the strength

of this modality. It was surmised that CAC with its strong

association to the burden of atherosclerosis could be focused

as a measure of a patient’s global cardiac risk. Since this 2000

ACC document,1 there has been an explosion of available

prognostic evidence as to the accuracy of CAC to estimate

major adverse cardiovascular events. This chapter will pro-

vide a theoretical perspective on how evidence of CAC can

estimate cardiovascular outcomes as well as a synopsis of

available data on this subject. Much of the discussion on the

prognostic value of CAC will focus on the use of the

Agatston score as the lion’s share of outcomes data have

been derived using this calculation.