Electron beam computed tomographic coronary calcium score cutpoints and severity of associated angiographic lumen stenosis

Objectives. We sought to determine a range of cutpoints for coronary calcium scores measured by electron beam computed tomography (EBCT) in predicting the likely severity of associated angiographic coronary artery stenoses. Background. EBCT can quantify coronary calcium and allow the estimation of atherosclerotic plaque burden, but use of the calcium score to define lumen narrowing is controversial. Methods. A total of 213 patients (mean [+/-SD] age 50 +/- 9 years) underwent coronary angiography and EBCT. Maximal percent diameter stenosis in any artery was paired with total coronary calcium score. Receiver operating characteristic (ROC) curve analysis was done using definitions of ''disease'' for maximal stenosis from greater than or equal to 20% to 100%, and the corresponding score cutpoints were determined for 90% sensitivity, 90% specificity or ''optimal'' sensitivity and specificity. Results. ROC curve areas ranged from a mean (+/-SE) of 0.91 +/- 0.02 for greater than or equal to 20% stenosis to 0.83 +/- 0.03 for 100% stenosis. Optimal calcium score cutpoints consisted of nonoverlapping values ranging from 15 for greater than or equal to 20% stenosis to 327 for 100% stenosis, whereas sensitivities and specificities ranged from 78% to 84%, depending on maximal stenosis severity. Calcium score cutpoints for 90% sensitivity and 90% specificity were also nonoverlapping and ranged from 3 and 27, respectively, for greater than or equal to 20% stenosis to 154 and 945, respectively, for 100% stenosis; corresponding specificities and sensitivities ranged from 40% to 78%. Conclusions. These data define the ranges for EBCT coronary calcium score cutpoints that predict the likely severity of associated maximal angiographic stenosis severity to a high sensitivity, high specificity or optimal sensitivity/specificity. These cutpoints potentially can be used in conjunction with clinical variables to predict the severity of lumen narrowing in patients undergoing assessment for coronary artery disease. (C) 1997 by the American College of Cardiology.