Independent and incremental value of coronary artery calcium for predicting the extent of angiographic coronary artery disease - Comparison with cardiac risk factors and radionuclide perfusion imaging

OBJECTIVES The study was done to test the ability to predict the extent of angiographically determined coronary artery disease (CAD) by quantification of coronary calcium using electron-beam computed tomography (EBCT) and to compare it with more conventional parameters for delineating the angiograph ic extent of CAD, that is, cardiovascular risk factors and radionuclide sin gle-photon emission computed tomography (SPECT). BACKGROUND The angiographic extent of CAD is a powerful predictor of subseq uent events. Use of EBCT may be able to define it by virtue of its ability to determine plaque burden. METHODS We examined 308 patients presenting with suspected but not previous ly known CAD who underwent selective coronary angiography. As measures of t he angiographic extent of CAD, coronary artery greater even 20 (CAGE greate r than or equal to 20) arid CAGE greater than or equal to 50 scores represe nted the total number of coronary segments with greater than or equal to 20 % or greater than or equal to 50% stenoses, respectively. The EBCT derived total calcium scores were obtained in 291 patients, risk factors as defined by the National Cholesterol Education Program in 239 patients, and SPECT s cans in 136 patients. RESULTS Using multiple linear regression analysis, total calcium scores wer e better independent predictors of both CAGE greater than or equal to 20 an d CAGE greater than or equal to 50 scores than either a SPECT-derived radio nuclide perfusion score or the risk factors age, male gender and ratio of t otal/high density lipoprotein (HDL) cholesterol. The association between EB CT and angiographic scores remained highly significant after excluding the influence of all interrelated risk factors and SPECT variables (r = 0.65; p < 0.001 for CAGE greater than or equal to 20 scores, r = 0.50; p < 0.001 f or CAGE greater than or equal to 50 scores). CONCLUSIONS Coronary calcium predicts the angiographic extent of CAD in sym ptomatic patients and provides independent and incremental information to t he more conventional clinical parameters derived from SPECT or risk assessm ent. a Am Coil Cardiol 1999;34:777-85) (C) 1999 by the American College of Cardiology.