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.