Evaluation of Clinical Applicability of Coronary Artery Calcium Assessment on Non–Gated Chest Computed Tomography, Compared With the Classic Agatston Score on Cardiac Computed Tomography

Abstract

Given current pretest probability (PTP) estimations tend to overestimate patients' risk for obstructive coronary artery disease, evaluation of patients' coronary artery calcium (CAC) is more precise. The value of CAC assessment with the Agatston score on cardiac computed tomography (CT) for risk estimation has been well indicated in patients with stable chest pain. CAC can be equally well assessed on routine non-gated chest CT, which is often available. This study aims to determine the clinical applicability of CAC assessment on non-gated CT in patients with stable chest pain compared with the classic Agatston score on gated CT. Consecutive patients referred for evaluation of the Agatston score, who had a previously performed non-gated chest CT for evaluation of noncardiac diseases, were included. CAC on non-gated CT was ordinally scored. Subsequently, patients were stratified according to CAC severity and PTP. The agreement and correlation between the classic Agatston score and CAC on non-gated CT were evaluated. The discriminative power for risk reclassification of both CAC assessment methods was assessed. Invasive coronary angiography was used as the gold standard, when available. A total of 140 patients aged between 30 and 88years were included. The agreement between ordinally scored CAC and the Agatston score was excellent (κ=0.82) and the correlation strong (r=0.94). Most patients (80%) with an intermediate PTP had no or mild CAC on non-gated CT. They were reclassified at low risk with 100% accuracy compared with invasive coronary angiography. Similarly, 86% of patients had an Agatston score <300. These patients were reclassified with 98% accuracy. In patients with high PTP, the accuracy remained substantial and comparable, 94% and 89%, respectively. In conclusion, we believe this is the first study to assess the clinical applicability of CAC on non-gated CT in patients with stable chest pain, compared with the classic Agatston score. The agreement between methods was excellent and the correlation strong. Furthermore, CAC assessment on non-gated CT could reclassify patients' risk for obstructive coronary artery disease as accurately as could the classic Agatston score.