Diagnostic efficacy of coronary calcium score in the assessment of significant coronary artery stenosis.

BACKGROUND Coronary artery calcium score (CCS) is a quantitative assessment of calcifications detectable by multidetector computed tomography (MDCT). AIM To evaluate diagnostic accuracy of CCS to detect significant stenosis in coronary arteries in symptomatic patients. METHODS The study population included consecutive symptomatic patients with suspected coronary artery disease (CAD) who were referred for coronary angiography. The group included 158 patients (64.6% males) who were all evaluated by unenhanced 64-slice computed tomography where calcium was quantified according to the Agatston method. The ROC curves were constructed to evaluate the discriminating power of the total CCS and CCS for each individual coronary artery in predicting the presence of significant stenosis. RESULTS The prevalence of significant CAD strongly increased with higher CCS. The area under the curve (AUC) for total CCS for diagnosing significant stenosis (> or = 50%) in at least one coronary artery was 0.83 (95% CI 0.74-0.92). Using the cut-off value of CCS > or = 7.7 at least one significant coronary stenosis was detected with the sensitivity and specificity of 86% and 71%, respectively. Significant coronary artery stenosis was better predicted by measuring CCS for individual coronary arteries than total CCS. The AUC of CCS for significant stenosis of each coronary artery was 0.80 for the right coronary artery (RCA), 0.72 for the left main (LM), 0.73 for the left anterior descending (LAD) and 0.76 for the left circumflex arteries (LCX). The optimal cut-off point was estimated for CCS of each coronary artery. It was set at > or = 3.1 for RCA, > or = 7.7 for LM, > or = 9.5 for LAD and > or = 4.5 for LCX. Positive and negative predictive values for an intact artery using a CCS of zero were 92.8% and 83.8%, respectively. Diagnostic performance of CCS for predicting stenosis of LM and LCX arteries was better in patients over age 65 than in younger patients. CONCLUSIONS Coronary artery calcium score is useful in predicting coronary artery stenosis, especially in subjects in whom invasive diagnostic or therapeutic utilities seem to be used untimely. The current study suggests an optimal cut-off value of total CCS > or = 7.7 for detecting significant stenosis, and underlines the better predictive value for CCS of individual arteries.