Coronary Artery Calcium Scores Using Nongated Computed Tomography

Abstract

The coronary artery calcium (CAC) score is well established as a potent marker of increased cardiovascular risk that significantly improves risk prediction beyond traditional risk factors. A CAC score >300 has been shown to confer a 10-fold increase in the risk for a cardiovascular event compared with adults with a CAC of 0.1,2 The improvement in risk prediction is substantially greater with CAC than other imaging and serum markers of subclinical cardiovascular disease.3,4 Article see p 514 The cohort studies that have most informed our understanding of coronary calcium measured CAC scores with dedicated cardiac computed tomography (CT). Image acquisition was gated to diastole to minimize motion artifact and to decrease the likelihood that regions of CAC were missed. However, most chest CTs done for clinical purposes are ordered primarily to assess the lungs and other structures in the chest and thus are not gated. Without gating, there is a concern that assessment of CAC is not accurate. Rather than disregard readily available data, several investigators have sought to determine whether information about CAC burden from nongated CTs can be used effectively to predict cardiovascular risk. In this issue of Circulation: Cardiovascular Imaging , Xie et al5 compiled data from several studies to determine the validity and prognostic value of CAC scoring obtained on nongated thoracic CT scans. To assess the diagnostic performance, the authors performed a meta-analysis of 5 studies that directly compared CAC scores obtained using gated versus nongated CTs. The patient populations in the studies varied, with some representing adults consecutively referred for a chest CT, positron …