Coronary calcium score and computed tomography coronary angiography in high-risk asymptomatic subjects: assessment of diagnostic accuracy and prevalence of non-obstructive coronary artery disease.

OBJECTIVES: The aim of the study was to compare the coronary artery calcium score (CACS) and computed tomography coronary angiography (CTCA) for the assessment of non-obstructive/obstructive coronary artery disease (CAD) in high-risk asymptomatic subjects. METHODS: Two hundred and thirteen consecutive asymptomatic subjects (113 male; mean age 53.6 +/- 12.4 years) with more than one risk factor and an inconclusive or unfeasible non-invasive stress test result underwent CACS and CTCA in an outpatient setting. All patients underwent conventional coronary angiography (CAG). Data from CACS (threshold for positive image: Agatston score 1/100/1,000) and CTCA were compared with CAG regarding the degree of CAD (non-obstructive/obstructive; </>/=50% lumen reduction). RESULTS: The mean calcium score was 151 +/- 403 and the prevalence of obstructive CAD was 17% (8% one-vessel and 10% two-vessel disease). Per-patient sensitivity, specificity, positive and negative predictive values of CACS were: 97%, 75%, 45%, and 100%, respectively (Agatston >/=1); 73%, 90%, 60%, and 94%, respectively (Agatston >/=100); 30%, 98%, 79%, and 87%, respectively (Agatston >/=1,000). Per-patient values for CTCA were 100%, 98%, 97%, and 100%, respectively (p < 0.05). CTCA detected 65% prevalence of all CAD (48% non-obstructive), while CACS detected 37% prevalence of all CAD (21% non-obstructive) (p < 0.05). CONCLUSION: CACS proved inadequate for the detection of obstructive and non-obstructive CAD compared with CTCA. CTCA has a high diagnostic accuracy for the detection of non-obstructive and obstructive CAD in high-risk asymptomatic patients with inconclusive or unfeasible stress test results.