Journal of the American College of Cardiology Vol. 61, No. 8, 2013© 2013 by the American College of Cardiology Foundation ISSN 0735-1097/$36.00Published by Elsevier Inc. http://dx.doi.org/10.1016/j.jacc.2013.01.002

EDITORIAL COMMENT

Coronary ComputedTomography Angiographyin the Emergency DepartmentThe High Stakes Gameof Low Risk Chest Pain*

Wm. Guy Weigold, MD

Washington, DC

Decades of educating the public about the warning signs ofa heart attack has had the beneficial effect of promptingindividuals with bona fide myocardial infarction to quicklyseek medical attention, but at the same time induces manymore individuals experiencing benign chest pain to presentto emergency departments (ED) for evaluation. Eventhough most patients with acute chest pain are not ulti-mately diagnosed with acute coronary syndrome, establish-ing this with certainty consumes time, labor, already over-crowded ED and hospital space, and money. Despite effortsto improve the triage of this presentation, up to 5% of acutecoronary syndromes are still missed (1,2), and these undi-agnosed patients face a higher adverse event rate than thosewho are correctly diagnosed (3), such that even low missrates are essentially intolerable. Hence, ED physicians facethe difficult challenge of trying to be nearly perfect predic-tors of their patients’ outcomes at the same time that theymust lower costs and shorten patient turnaround time, andthey must do this in today’s highly litigious environment (4).All together, these factors understandably incline many EDphysicians to use cardiac imaging as a way to boost theirchances of successfully managing this common and chal-lenging entity.

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Soon after its emergence, it was realized that coronarycomputed tomographic angiography (CTA) possessed animpressive ability to accurately exclude coronary arterydisease and coronary stenosis. Given its strong negative

*Editorials published in the Journal of the American College of Cardiology reflect theviews of the authors and do not necessarily represent the views of JACC or theAmerican College of Cardiology.

From the Cardiology Division, MedStar Heart Institute, MedStar Washington

Hospital Center, Washington, DC. Dr. Weigold has reported that he has norelationships relevant to the contents of this paper to disclose.

predictive power and rapid turnaround time, there has longbeen interest in using coronary CTA to aid the evaluation ofchest pain in the ED. Recently, the small number ofrandomized trials evaluating this question has grown, andthe study by Hulten et al. (5), in this issue of the Journal, isthe first meta-analysis to examine randomized controlledtrials of ED triage of acute chest pain using coronary CTA,comparing this relatively new approach to more traditionalusual care (UC) methods.

Four trials were adequate for inclusion, totaling 3,266patients. Generally speaking, there were similar inclusion/exclusion criteria across the studies, and patients had similarcoronary heart disease risk factors in the CTA and compar-ison groups. There were no deaths in any of the studies anda minimal number of myocardial infarctions. This is perhapsnot surprising given the low-risk population selected, but atestament to the safety of the CTA approach nonetheless,especially given the rapid turnaround times for the CTpatients: in most cases, a “negative” coronary CTA meantimmediate discharge home. Invasive coronary angiography(ICA) occurred in 7.6% of the CT subjects (8.4% when thedata are pooled and weighted) and 6.3% of the UC subjects(same when pooled and weighted). Hence, the absolutedifference in the pooled weighted incidences was about 2%,with an odds ratio of 1.36, though with a lower confidencelimit just above the threshold of statistical significance at1.03. Similarly, revascularization occurred in 4.1% of theCT subjects (4.6% when pooled and weighted) and 2.6% ofthe UC group, which perhaps is not surprising given thatthere was a slightly higher rate of ICA in the CT group.

This meta-analysis did not attempt to compare length ofstay or cost because of the methodological heterogeneity ofthe studies, but the investigators point out that all of thesource studies reported significant reductions in length ofstay for the CT group. Coronary CTA is a quick procedure;most patients, having already established intravenous accessand received beta-blockers in the ED, are in and out of thescanner room in 20 min. At our center, we usually have thereading done before the patient makes it back to the ED.Our ED physicians find this time-saving approach ex-tremely helpful as they battle the time constraints socommon to any busy ED. Hulten et al. also point out thatin addition to saving time, all the source studies thatevaluated ED cost reported significant cost savings. Thesedata have supported the hypothesis that a CT strategy in theevaluation of ED chest pain saves time and money, and itsuse in this scenario is supported by recent guidelines (6,7).

Hulten et al. (5) conclude from their meta-analysis thatthe use of coronary CTA to triage ED chest pain is safe,consistently reduces length of stay, and reduces ED cost, butcompared with traditional methods, is associated withslightly higher rates of ICA and revascularization. Thesedifferences were not statistically significant in any of thesource studies, but they do reach the statistical threshold

with the increased number of subjects afforded by the

894 Weigold JACC Vol. 61, No. 8, 2013Coronary CT Angiography in the ED February 26, 2013:893–5

meta-analysis approach. Even though the demonstration ofthis correlation does not prove that coronary CTA “leads” toICA or revascularization, it is an intriguing finding worthexamining more closely.

It is important to point out that there were somesignificant differences in methodology among these 4 stud-ies. The studies by Goldstein et al. (8) and the CT-STAT(Coronary Computed Tomographic Angiography for Sys-tematic Triage of Acute Chest Pain Patients to Treatment)Investigators (9) were comparisons of CT not to clinicaltriage but to another imaging modality, namely single-photon emission CT (SPECT); no patients were to bedischarged without 1 of these 2 imaging tests (8,9). Perhapsthis is relevant: in CT-STAT, the 6-month cumulative ICArates in the 2 groups were nearly the same: 8% in the CTAgroup versus 7.4% in the single-photon emission CT group(p � 0.78). This is different from ROMICAT II (Rule OutMyocardial Ischemia/Infarction Using Computer AssistedTomography) and ACRIN PA 4005 (CT Angiography forSafe Discharge of Patients With Possible Acute CoronarySyndromes) trials in which patients could potentially bedischarged without any testing. Hence, they were notsusceptible to the false-positive tests that plague somenoninvasive modalities. Goldstein et al. (8) and CT-STAT(9) were also different in that the protocol required recom-mending additional testing after CT given certain criteria:SPECT for any stenosis �25%, or even just a calcium score�100, and ICA for any stenosis �70%. This very conser-vative approach may well have contributed to a highercatheterization rate. Indeed, when those 2 studies areremoved, the lower confidence limit of the odds ratio forICA in the CT group nudges even closer to the nonsignif-icant level at 1.004. Hence, the association demonstratedbetween CT and ICA is not exactly strong.

That aside, Hulten et al. (5) point out that ICA andrevascularization contribute to the cost of care. This, gen-erally speaking, is true, but raises 2 other issues worthpointing out. The first is particular to the studies of acutechest pain triage, which is that most patients (�90%) inthese studies did not undergo either ICA or revasculariza-tion. In the evaluation of acute chest pain, the morefrequent source of cost is the diagnostic workup in the ED.In this regard, the use of coronary CTA, compared to theUC strategy, has consistently been shown in multiplerandomized trials to reduce ED costs and to offset the costof additional ICA or revascularization.

The second issue concerns those catheterizations andrevascularizations and is a more general point pertaining tohealthcare costs. As we try to reduce healthcare spending,let us not confuse quantity with quality. Whereas someadvocate broadly curtailing the use of all tests and proce-dures in a nearly indiscriminate fashion, in fact the use ofthese tools, and the costs associated with their use, are eitherjustified or unjustified depending on the circumstances ofthe particular patients and clinical scenarios in which we use

them. We should not seek to reduce the usage of resources

just for its own sake; rather, we should look for ways toreduce unnecessary usage. For this reason, comparing theincidence of downstream resource utilization after coronaryCTA, though an interesting start, only touches the surfaceof the issue. The more critical issue is whether theseprocedures are being used appropriately. However, thequestion of appropriateness was not examined by thismeta-analysis or any of the source studies and for a varietyof good reasons. There are numerous and varied factors thatplay into the decision to perform these procedures; clinicaloutcome studies in this patient population would requirelarge numbers of subjects because event rates are low; anddiagnostic tests themselves do not exert any treatment effect,so to truly test the effect of a diagnostic strategy on clinicaloutcomes requires that treatments and therapies be strictlydictated, per protocol, by the results of the test.

Yet the data in hand may provide a little insight. In all ofthe source studies, individually and as a whole, catheteriza-tions prompted by coronary CTA were more often followedby revascularization than were catheterizations prompted byother approaches. Some would say that this indicates thatcoronary CTA drives revascularization, but this is not thecase. The decision to revascularize is generally made basedon the findings of the invasive angiogram, not the nonin-vasive test that preceded it. Instead, it would appear thatwhen the coronary CTA strategy does prompt an invasiveangiogram, those angiograms provide a higher diagnosticyield. For example, in ACRIN PA 4005, there wereequivalent rates of cardiac catheterization in the CTA andcontrol arms (4%), but in the CTA group, the prevalence ofsignificant disease on the invasive angiogram was 76%versus 44% in the traditional care group (10). Across the 4studies included in this meta-analysis, the diagnostic yield ofcatheterizations prompted by coronary CTA was higherthan for those prompted by usual care (54% vs. 41%), evenincluding the requirements to test and catheterize in-cluded in Goldstein et al. (8) and CT-STAT (9). Thesedata suggest that the CTA strategy may help selectpatients for ICA and thereby reduce the number ofunnecessary catheterizations.

If the CTA strategy reduces the number of unnecessarycatheterizations, then why were there more revasculariza-tions in the CTA group? Perhaps the real question is whythere were fewer revascularizations in the UC group. All thepatients in the CTA group essentially got an angiogram,and coronary CTA is exquisitely sensitive for the detectionof coronary disease. On the other hand, 94% of the patientsin the UC group never had their coronary arteries “lookedat.” That is not necessarily a bad thing. But, are somepatients in the UC group with obstructive coronary diseasebeing missed and sent home without that diagnosis? Per-haps. Do they suffer a higher morbidity or mortality thanthose detected and revascularized? Presumably that dependson the extent and severity of their disease, but we will notknow until we have much larger studies to find out. In the

meantime, the time pressures, budget constraints, and legal

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895JACC Vol. 61, No. 8, 2013 WeigoldFebruary 26, 2013:893–5 Coronary CT Angiography in the ED

consequences of managing this presentation loom, and thesevery real forces will continue to put pressure on front-linephysicians and strain our healthcare resources. In the end, itmay be our healthcare delivery systems that benefit mostfrom a fast, accurate, cost-saving test.

Reprint requests and correspondence: Dr. Wm. Guy Weigold,MedStar Washington Hospital Center, 110 Irving Street NW,Suite 4B-1, Washington, DC 20010. E-mail: guy.weigold@medstar.net.

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3. Lee TH, Goldman L. Evaluation of the patient with acute chest pain.N Engl J Med 2000;342:1187–95.

4. Anderson RE. Defending the practice of medicine. Arch Intern Med2004;164:1173–8.

5. Hulten E, Pickett C, Bittencourt MS, et al. Outcomes after coronarycomputed tomography angiography in the emergency department: asystematic review and meta-analysis of randomized, controlled trials.J Am Coll Cardiol 2013;61:880–92.

6. Taylor AJ, Cerqueira M, Hodgson JM, et al. ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 appropriate use cri-

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7. Wright RS, Anderson JL, Adams CD, et al. 2011 ACCF/AHAfocused update incorporated into the ACC/AHA 2007 Guidelines forthe Management of Patients with Unstable Angina/Non–ST-Elevation Myocardial Infarction: a report of the American College ofCardiology Foundation/American Heart Association Task Force onPractice Guidelines developed in collaboration with the AmericanAcademy of Family Physicians, Society for Cardiovascular Angiogra-phy and Interventions, and the Society of Thoracic Surgeons. J AmColl Cardiol 2011;57:e215–367.

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Key Words: coronary angiography y coronary artery bypass graft

urgery y coronary computed tomography angiography y emergencyepartment y percutaneous coronary intervention.