BackgroundCoronary artery calcium score (CACS) is a quantitative assessment of calcifications and an established predictor of cardiovascular events.ObjectivesIn this study, we evaluated the diagnostic accuracy, negative predictive value (NPV), positive predictive value (PPV), specificity and sensitivity of CACS less than 100 in predicting significant coronary artery stenosis in patients with risk of coronary artery disease (CAD) in a vessel-based analysis.Patients and MethodsA cross sectional study was carried out on a study population of 2527 consecutive stable patients with symptoms suggestive of CAD who were referred for coronary computed tomographic angiography (CCTA). We performed 1343 studies with 256 slice machine in Shahid Rajaee hospital and the other studies were carried out with 64 slice machine in Imam Khomeini hospital and the calcium score was quantified according to the Agatston method.ResultsAt the cutoff point of 100 for coronary calcium scoring, there was high specificity (87%), high sensitivity (79%), high efficiency (84%), high PPV (79%), and high NPV (87%) in the diagnosis of significant stenosis in the whole heart. The frequency of zero calcium scoring was 59% in normal or nonsignificant stenosis and 7.6% in significant stenosis in the whole heart. Calcium scoring increased with greater severity of the arterial stenosis (P values < 0.001).ConclusionWe conclude that coronary calcium scoring provided useful information in the management of patients. In CACS less than 100, it has a NPV of 87% in excluding significant stenosis in patients with the risk of CAD but it does not have enough diagnostic accuracy for surely excluding coronary stenosis, so we should perform a combination of CACS and coronary CT angiography for patients.