Prognostic Value Of Coronary Artery Calcium Score In Addition To Single Photon Emission Computed Tomography Myocardial Perfusion Imaging In Symptomatic Patients

The prognostic value of coronary artery calcium (CAC) scoring on top of myocardial perfusion imaging with single-photon emission computed tomography (SPECT) in patients suspected for coronary artery disease is not well established.Four thousand eight hundred ninety-seven symptomatic patients without a history of coronary artery disease referred for SPECT and CAC scoring were included. Major adverse cardiac events (MACEs) were defined as late revascularization (>90 days after scanning), nonfatal myocardial infarction, and all-cause mortality. The frequency of abnormal SPECT increased with higher CAC scores, from 12% in patients with CAC scores of 0 to 19%, 32%, 37%, and 50% among those with CAC scores 1 to 99, 100 to 399, 400 to 999, and ≥1000, respectively (P<0.001). During a median follow-up of 940 days (25th to 75th percentile, 581-1377), a total of 278 MACEs were observed. Overall incidence of MACE was 2.3% per year. A stepwise increase of MACE was present with increasing CAC scores, both in patients with normal SPECT (annual event rate CAC score 0: 0.6%; CAC score ≥1000: 5.5%) and abnormal SPECT (annual event rate CAC score 0: 0.4%; CAC score ≥1000: 7.6%). After multivariate analysis, both SPECT and CAC score were independent predictors of MACE (CAC score ≥1000: hazard ratio, 7.7; P<0.001 and large perfusion defect on SPECT: hazard ratio, 3.7; P<0.001).CAC score and SPECT are independent predictors of MACE in patients suspected for coronary artery disease. Our findings strongly support performing a CAC score in addition to SPECT in symptomatic patients to better define the risk of events during follow-up.