Coronary calcifications as assessed on routine non-gated chest CT; a gatekeeper to tailor downstream additional imaging in patients with stable chest pain

Background and aims: Currently applied methods for risk -assessment in coronary artery disease (CAD) often overestimate patients ' risk for obstructive CAD. To enhance risk estimation, assessment of coronary artery calcium (CAC) can be applied. In 10 % of patients presenting with stable chest pain a previous non -gated computed tomography (CT) has been performed, suitable for CAC -assessment. This study is the first to investigate the clinical utility of CAC -assessment on non -gated CT for risk -assessment of obstructive CAD in symptomatic patients. Methods: For this analysis, all patients referred for coronary computed tomography angiography (CCTA), in whom a previous non -gated chest CT was performed were included. The extent of CAC was assessed on chest CT and ordinally scored. CAD was assessed on CCTA and obstructive CAD defined as stenosis of >= 70 %. Patients were stratified according to CAC -severity and percentages of patients with obstructive CAD were compared between the CAC groups. Results: In total, 170 patients of 32 -88 years were included and 35 % were male. The percentage of obstructive CAD between the CAC groups differed significantly (p < 0.01). A calcium score of 0 ruled out obstructive CAD irrespective of sex, pre-test probability, type of complaints and number of risk factors with a 100 % certainty. Furthermore, a mild CAC score ruled out obstructive CAD in patients with low - intermediate PTP or non -anginal complaints with 100 % certainty. Conclusion: When available, CAC on non -gated chest CT can accurately rule out obstructive CAD and can therefore function as a radiation -free and cost-free gatekeeper for additional imaging in patients presenting with stable chest pain.