Uncertainty exists as to whether coronary CT angiography (CTA) compared with standard of care (SOC) is more effective and efficient in the triage of low-risk emergency department (ED) patients with acute chest pain. Our objective was to construct a simulation model to estimate clinical and economic outcomes.We constructed a microsimulation model comparing SOC to coronary CTA-based triage of 1000 55-year-old patients (50% men) with acute chest pain, nonsignificant ECG changes, and initial negative cardiac markers. In SOC, patients were reevaluated with serial cardiac markers after 6-8 hours, followed by either nuclear stress imaging (SPECT) or stress echocardiography. In coronary CTA-based triage, patients were imaged immediately and, depending on the results, discharged, held for SPECT or stress echocardiography, or referred directly to invasive coronary angiography.Compared with SOC, coronary CTA-based triage reduced the number of patients referred for invasive coronary angiography from 406 (SPECT) or 370 (stress echocardiography) to 255 per 1000 and resulted in fewer "missed" cases of acute coronary syndrome overall (5 vs 18). Coronary CTA-based triage also resulted in fewer deaths (4 vs 6). Coronary CTA led to immediate discharge of 706 patients and produced average cost-savings in the ED of $851 (SPECT) or $462 (stress echocardiography) per patient. At 30 days after initial ED triage, coronary CTA-based management produced average savings of $283 (SPECT) and average costs of $292 (stress echocardiography) per patient triaged.Our model suggests that coronary CTA-based triage of low-risk patients with acute chest pain in the ED might reduce invasive catheterizations, could improve survival, and may save money.