Use of coronary artery calcium scanning as a triage for invasive coronary angiography

Excerpt

The presence of coronary artery calcium (CAC) is an important marker of atherosclerosis burden and the evaluation of the extent of CAC may be used in clinical management of asymptomatic patients at intermediate risk of coronary artery disease (CAD).1 The presence of high CAC score is associated with higher probability of significant obstructive CAD and is also a strong predictor for risk assessment of hard cardiovascular events, such as myocardial infarction and sudden cardiac death.2 Patients with values of CAC score > 400 are at higher risk of adverse cardiac events and need more advanced testing.3 On the other hand, myocardial perfusion imaging (MPI) is a useful noninvasive method for diagnostic and prognostic evaluation of patients with suspected CAD.4 The introduction of hybrid imaging as single photon emission computed tomography (SPECT)/computed tomography (CT) and positron emission tomography/CT allows to perform morphological and functional imaging in a same study session with a comfortable accuracy.5 A combined evaluation of functional and structural abnormalities allows to improve the detection of obstructive CAD and to better stratify patients at low-intermediate risk of CAD.6 Previous studies demonstrated that the major predictors of events in patients with suspected CAD are the extent of atherosclerotic burden, assessed by CAC, and the extent and severity of stress-induced myocardial ischemia, as assessed by MPI.7 The evaluation of CAC content in association with myocardial perfusion may improve specificity and positive predictive value for the detection of CAD, in particular in patients with a CAC score value more than zero.8 However, subclinical atherosclerosis may be also frequently present in patients with normal myocardial perfusion and a normal MPI does not necessarily exclude significant coronary stenosis.9,10 …