Interestingly, between 12 and 18 hours, the CCTA arm had three times as many patients discharged than standard care (60% versus 20%). Also, the CCTA arm had three times the number of patients discharged directly from the emergency department, half the number admitted for observation, and a mean time to diagnosis of 10 hours compared with 19 hours for the standard care patients. When patients had a negative CCTA scan, the mean cost of care was 19% lower than standard care. But when patients in the CCTA arm were admitted to the hospital, their cost doubled compared with standard care patients. The cost increase was mainly driven by the implantation of stents or bypass surgery. Overall, however, the costs balanced out. "We were happy to see there was no overall increase in cost," Hoffmann said. However, the study only allowed enrollment during normal weekly business hours. It was noted that if the strategy expands to 24/7 availability, the initial costs and downstream costs could increase. Hoffmann pointed out that none of the nine sites in the study had routinely used CCTA in the emergency department for chest pain patients. Whether they will continue using CCTA in this manner remains to be seen. "The physicians know the findings of this study. Now they have to determine their own threshold as to where they are comfortable with the technology," he said. Radiation exposure is a topic that always surfaces when discussing cardiac CT scanning, and Hoffmann's presentation did not disappoint. He said that the cumulative radiation exposure, including from CCTA, SPECT, and catheter angiography during the index visit and follow-up, was three times as high in the CCTA arm: 14 mSv versus 5 mSv. Discussant Elliott Antman, MD, from Brigham and Women's Hospital in Boston, suggested that patients could be exposed to even higher radiation if they went to different hospitals that weren't aware of their previous CT scans. Hoffmann noted that in CT-STAT, which compared CCTA to SPECT, the radiation exposure favored CT: 11 versus 14 mSv. "This trial is biased in a way because all patients in the CT arm had coronary CT, but only 40% of patients in the other arm had a test that exposed them to radiation," he said. Newer CT technology allows the radiation dose to be cut by 50%, he said. And some state-of-the-art scanners can deliver doses as low as 3 mSv. "Remember, we have to balance the improved decision making, which frees up beds in the hospital, and lower rates of false diagnostic catheter angiographies," he said. But, he acknowledged, electronic medical records that document a patient's previous CCTA scans could help determine whether another CT scan is warranted. Primary source: American College of Cardiology Source reference: Hoffmann U, et al “ROMICAT II - Rule out myocardial ischemia/infarction using computer assisted tomography” ACC 2012. Additional source: Journal of the American College of Cardiology Source reference: Goldstein J, et al “The CT-STAT coronary computed tomographic angiography for systematic triage of acute chest pain patients to treatment trial” J Am Coll Cardiol 2011; 58: 1414-1422.