OBJECTIVES: Coronary multidetector computed tomography (MDCT) and myocardial perfusion imaging (MPI) are diagnostic modalities used to identify patients with coronary artery disease (CAD). We used Episode Treatment Groups™ (ETG) software, an industry standard for combining healthcare billing information into specific episodes of care, to examine CAD-related costs and clinical outcomes of individuals who underwent diagnostic evaluation by either MDCT or MPI. METHODS: Patients without known CAD who underwent either MDCT or MPI as an initial diagnostic test were identified from a multicenter database using complete facility, physician and pharmacy data from two large health care plans from 2003-05. 1-year downstream CAD-related episodes of care were examined for patients after initial MDCT or MPI. Costs were further sub-classified by utilization of high-cost resources, including cardiac catheterization, percutaneous transluminal coronary angioplasty (PTCA), and coronary artery bypass surgery (CABG). RESULTS: A total of 18,489 patients underwent either MDCT (n=638) or MPS (n=17,851) testing during the study period. While costs per CAD-related episodes were similar between MDCT and MPS groups ($5,878 vs. $6,079, p=0.20), patients undergoing MDCT had fewer total numbers of CAD-related episodes of care (4.246 vs. 5.065, p <.0001). High-cost CAD test utilization was also lower for MDCT patients compared to MPI patients for cardiac catheterization (15.673 vs. 29.132, p<0.0001), PTCA (0.940 vs. 2.341, p=0.020), and CABG (2.351 vs. 5.274, p=0.001). After adjustment for age, gender, baseline cardiovascular risk, and baseline health status, one-year total CAD-related episodes of care costs for MDCT were 16.4% lower than MPS, by an average of $800 (95% CI, $39-$1394) per patient. CONCLUSION: Patients without known CAD who undergo MDCT as an initial diagnostic test, compared to MPI, incurred fewer CAD-related episodes of care and underwent fewer incident high-cost tests. These data suggest that MDCT may be a potential cost-saving alternative to MPS for initial evaluation of patients with suspected CAD.