Abstract 323: Assessment of Coronary Artery Calcium on Routine Non-gated Chest Computed Tomography to Risk Stratify Patients Presenting With Chest Pain

Abstract

Background: Coronary artery calcium (CAC) scoring is an important tool for cardiovascular risk stratification. CAC scoring in both asymptomatic and symptomatic, low-intermediate risk patients has also shown prognostic utility and has a high negative predictive value for obstructive coronary artery disease (CAD). Patients who present with chest pain frequently undergo non-gated chest computed tomography (CT) to evaluate for non-cardiac etiologies. In fact, several studies have demonstrated that a CAC score from a non-gated chest CT correlates well with a dedicated calcium-scoring CT. However, the predictive value on CAD through assessing the presence (CAC>0) or the absence of calcium (CAC=0) detected on non-gated chest CT in patients presenting with chest pain is unknown. Methods: Low-intermediate risk patients (n=92) presenting to the emergency department with chest pain who underwent non-gated chest CT and were subsequently evaluated with either a cardiac stress test or invasive coronary angiography were included. Dichotomous CAC was assessed in a blinded fashion and classified as CAC=0 or CAC>0. Obstructive CAD was defined as either: ischemia on stress testing or any coronary artery stenosis greater than 70% (left main coronary artery stenosis greater than 50%) on invasive coronary angiography. Results: CAC=0 on non-gated chest CT was found in 59.2% (n=42). Patients with CAC=0 had a significantly lower age and TIMI score compared to patients with a CAC>0. (p<0.01 ) Patients with a CAC>0 were found to more likely have obstructive CAD on subsequent testing: cardiac stress test (Likelihood ratio[LR]:6.42, p=0.022); and invasive angiography (LR:12.46, p=0.002). There were no patients with a CAC=0 that were found to have obstructive CAD on invasive coronary angiography, resulting in a 100% sensitivity and 100% negative predictive value. Conclusion: Patient who presents with chest pain frequently undergo evaluation with a non-gated chest CT to assess non-cardiac etiologies. Exclusion of CAC on non-gated chest CT may be useful as an adjunct for further risk stratification to avoid potential adverse events and cost associated with further testing.