Coronary calcium score in the initial evaluation of suspected coronary artery disease

Objective: We evaluated coronary artery calcium (CAC) scoring as an initial diagnostic tool in outpatients and in patients presenting at the emergency department due to suspected coronary artery disease (CAD).

Methods: 10 857 patients underwent CAC scoring and coronary CT angiography (CCTA) at Haukeland University Hospital in Norway during 2013-2020. Based on CCTA, obstructive CAD was defined as at least one coronary stenosis ≥50%. High-risk CAD included obstructive stenoses of the left main stem, the proximal left ascending artery or affecting all three major vascular territories with at least one proximal segment involved.

Results: Median age was 58 years and 49.5% were women. The overall prevalence of CAC=0 was 45.0%. Among those with CAC=0, 1.8% had obstructive CAD and 0.6% had high-risk CAD on CCTA. Overall, the sensitivity, specificity, positive predictive value and negative predictive value (NPV) of CAC=0 for obstructive CAD were 95.3%, 53.4%, 30.0% and 98.2%, respectively. However, among patients <45 years of age, although the NPV was high at 98.9%, the sensitivity of CAC=0 for obstructive CAD was only 82.3%.

Conclusions: In symptomatic patients, CAC=0 correctly ruled out obstructive CAD and high-risk CAD in 98.2% and 99.4% of cases. This large registry-based cross-sectional study supports the incorporation of CAC testing in the early triage of patients with chest pain and as a gatekeeper to further cardiac testing. However, a full CCTA may be needed for safely ruling out obstructive CAD in the youngest patients (<45 years of age).