Characteristics of coronary artery calcium and its relationship to myocardial ischemia in Chinese patients with suspected coronary artery disease.

OBJECTIVE This study was aimed to investigate the characteristics of coronary artery calcium (CAC) in Chinese population with suspected coronary artery disease (SCAD). METHODS We studied 205 Chinese patients with SCAD who were subjected to combined MPI and CAC score (CACS) study on a hybrid single photon emission tomography/computed tomography (SPET/CT) scanner. RESULTS a) Among the 205 patients 132 (64.3%) had CACS=0 and 73 (35.6%) had CACS>0. Of those with CACS>0, 58 (28.3%) had CACS of 1∼399 and 15 (7.3%) had CACS≥400. b) The prevalence of CAC and CACS increased significantly with age (P<0.05). c) Age and hypertension were independent risk factors for CAC. d) The incidence of ischemic MPI for all 205 patients was 10.6% (14/132), 19.0% (11/58) and 33.3% (5/15). For patients with CACS=0, of 1∼399 and ≥400, respectively, showing significant difference (P=0.034), and significantly increased with CACS increasing (P=0.010). The incidence of ischemic MPI increased with increasing CACS from 10.6% (CACS=0) to 33.3% (CACS≥400). e) CACS was weakly correlated or not correlated. The value of the correlation coefficient was very small, P value was less than 0.05 with ischemic MPI (r=0.164, P=0.019) but the accuracy of the presence of CAC for detecting ischemic MPI was only 65.4% (134/205). f) The area under the ROC curve was 0.615 (P<0.05, 95% CI: 0.500∼0.729). CONCLUSION Compared with western populations, the prevalence of CAC and absolute CACS in Chinese population with intermediate likelihood of CAD was low. CACS was weakly correlated with ischemic MPI, the accuracy of the presence of CAC for predicting ischemic MPI was low. CACS was not a reliable screening tool prior to MPI in Chinese patients with SCAD.