CT Coronary Angiography in the Emergency Department
There are about eight million annual ER visits are for chest pain. However, for most of these patients, the symptoms are ultimately found not to have a cardiac cause. Triage of these patients is typically based on history, clinical examination, serial ECG and serial blood tests. Because of its high negative predictive value in selected patient populations, coronary computed tomographic angiography (CTA) may allow early discharge of patients from the emergency department. However, data determining whether such a CTA based strategy is safe is incomplete.
In a study presented at the ACC 2012 meeting (https://www.amepc.org/cdt/announcement/view/23) and published simultaneously in the NEJM, the authors randomly assigned low-to-intermediate-risk patients presenting with possible acute coronary syndromes to undergo CCTA or to receive traditional care. (1) The trial was funded by the Commonwealth of Pennsylvania, Department of Health and the American College of Radiology Imaging Network Foundation (ClinicalTrials.gov number, NCT00933400). Patients older than 30 years with a Thrombolysis in Myocardial Infarction risk score of 0 to 2 and signs or symptoms warranting admission or testing were enrolled at five centers in the United States. The primary outcome was safety, assessed in the subgroup of patients with a negative CCTA examination, with safety defined as the absence of myocardial infarction and cardiac death during the first 30 days after presentation.
The trial enrolled 1370 subjects: 908 in the CCTA group and 462 in the group receiving traditional care. The baseline characteristics were similar in the two groups. Of 640 patients with a negative CCTA examination, none died or had a myocardial infarction within 30 days (0%; 95% confidence interval [CI], 0 to 0.57). As compared with patients receiving traditional care, patients in the CCTA group had a higher rate of discharge from the emergency department (49.6% vs. 22.7%; difference, 26.8 percentage points; 95% CI, 21.4 to 32.2), a shorter length of stay (median, 18.0 hours vs. 24.8 hours; P<0.001), and a higher rate of detection of coronary disease (9.0% vs. 3.5%; difference, 5.6 percentage points; 95% CI, 0 to 11.2). There was one serious adverse event in each group.
The authors conclude that a CTA-based strategy for low-to-intermediate-risk patients presenting with a possible acute coronary syndrome appears to allow safe, expedited discharge from the emergency department of patients who would otherwise be admitted.
Also at the ACC meeting, not-yet-published results from the ROMICAT II trial were presented. The study randomized 1000 chest-pain patients with suspected acute coronary syndrome to either a CTA screening approach or standard care. The primary end point was length of stay. The average time to diagnosis was 10.4 hours in the CTA group versus 18.7 hours in the control group (p=0.001). Patients in the CCTA group were more likely to be discharged directly from the emergency department (46.7% vs. 12.4%), but only slightly less likely to be admitted to the hospital (25.4% vs. 31.7%). The safety of the CCTA-based approach was comparable to that of the standard approach. There were no missed ACS cases in either group, and major adverse events within 30 days were statistically similar in both the CCTA and standard-care groups (0.4 and 1.0, p=0.37). However, the ROMICAT II showed no cost-savings with the CCTA-first strategy. Hospital billing data show that the CCTA-first approach cost about 19% less per patient than the standard approach, but hospital costs were about 50% more with the CCTA approach, apparently because CCTA patients underwent more angiography (12% vs. 8%, p=0.04) and a statistically insignificant greater number of coronary interventions- either percutaneous intervention or bypass surgery (6.4% vs. 4.2%, p=0.16).
These and previous data (2,3) suggest that a CT-based approach is a safe option for selected (low-intermediate risk) patients.
References:
1. Litt HI, Gatsonis C, Snyder B, Singh H, Miller CD, Entrikin DW, Leaming JM, Gavin LJ, Pacella CB, Hollander JE. CT Angiography for Safe Discharge of Patients with Possible Acute Coronary Syndromes. N Engl J Med. 2012 Mar 26. [Epub ahead of print]
2. Hoffmann U, Bamberg F, Chae CU, et al. Coronary computed tomography angiography for early triage of patients with acute chest pain. The ROMICAT (Rule Out Myocardial Infarction Using Computer-Assisted Tomography) trial. J Am Coll Cardiol 2009; 53:1642-50.
3. Goldstein J, Chinnaiyan K, Abidov A, 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.