Coronary artery calcium score: Current status of clinical application and how to handle the results

The clinical significance of the coronary artery calcium score (CACS) has been discussed since Agatston et al. first reported its utility in 1990. CACS is less invasive and less expensive than contrast-enhanced coronary computed tomography (CT) angiography. However, to date, discussion continues on who is eligible for CACS assessment and how test results should be handled. Although the CACS cutoff value of 400 has been used in many previous studies for the detection of significant coronary artery disease (CAD) or cardiac event risk, other studies have reported that the frequency of significant ischemia, likelihood of CAD, and cardiac event rate are increasing, from mild to moderate CACS. The prognostic significance of patients with moderate CACS (1–400) is still uncertain, whereas in 2016, the Society of Cardiovascular CT and Society of Thoracic Radiology guidelines determined CACS ≥300 as moderate to severely increased risk. Another important value is CACS = 0. It is known that CACS = 0 decreases the likelihood of CAD after assessment of the pretest probability. In addition, management using statin therapy is a clinical situation that may benefit from CACS = 0. A previous study reported no significant difference in the prognosis between patients with and without statin therapy with CACS = 0. Some studies have reported the significance of the combination of CACS and noninvasive cardiac imaging, whereas CACS assessment is recommended for use in combination with risk assessment of pretest probability using clinical information including age, sex, and chest symptoms. While the utility of CACS in the management of CAD and primary prevention has been reconfirmed, the benefit of moderate values of CACS to predict prognosis with subsequent treatment and noninvasive cardiac imaging is still controversial.