Coronary Computed Tomography Angiography in the Emergency Department
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Journal of the American College of Cardiology Vol. 61, No. 8, 2013 2PubDITORIAL COMMENT
oronary Computedomography Angiographythe Emergency Department
he High Stakes GameLow Risk Chest Pain*
m. Guy Weigold, MD
cades of educating the public about the warning signs ofeart attack has had the beneficial effect of promptingividuals with bona fide myocardial infarction to quicklyk medical attention, but at the same time induces manyre individuals experiencing benign chest pain to presentemergency departments (ED) for evaluation. Evenugh most patients with acute chest pain are not ulti-tely diagnosed with acute coronary syndrome, establish-this with certainty consumes time, labor, already over-wded ED and hospital space, and money. Despite effortsimprove the triage of this presentation, up to 5% of acuteronary syndromes are still missed (1,2), and these undi-nosed patients face a higher adverse event rate than thoseo are correctly diagnosed (3), such that even low misses are essentially intolerable. Hence, ED physicians facedifficult challenge of trying to be nearly perfect predic-s of their patients outcomes at the same time that theyst lower costs and shorten patient turnaround time, andy must do this in todays highly litigious environment (4).l together, these factors understandably incline many EDysicians to use cardiac imaging as a way to boost theirances of successfully managing this common and chal-ging entity.
See page 880
Soon after its emergence, it was realized that coronarymputed tomographic angiography (CTA) possessed anpressive ability to accurately exclude coronary arteryease and coronary stenosis. Given its strong negative
itorials published in the Journal of the American College of Cardiology reflect thes of the authors and do not necessarily represent the views of JACC or the
013 by the American College of Cardiology Foundationlished by Elsevier Inc.difsouwi
erican College of Cardiology.rom the Cardiology Division, MedStar Heart Institute, MedStar Washingtonspital Center, Washington, DC. Dr. Weigold has reported that he has notionships relevant to the contents of this paper to disclose.dictive power and rapid turnaround time, there has longen interest in using coronary CTA to aid the evaluation ofest pain in the ED. Recently, the small number ofdomized trials evaluating this question has grown, andstudy by Hulten et al. (5), in this issue of the Journal, isfirst meta-analysis to examine randomized controlled
als of ED triage of acute chest pain using coronary CTA,mparing this relatively new approach to more traditionalal care (UC) methods.Four trials were adequate for inclusion, totaling 3,266tients. Generally speaking, there were similar inclusion/lusion criteria across the studies, and patients had similarronary heart disease risk factors in the CTA and compar-n groups. There were no deaths in any of the studies andinimal number of myocardial infarctions. This is perhapst surprising given the low-risk population selected, but atament to the safety of the CTA approach nonetheless,ecially given the rapid turnaround times for the CTtients: in most cases, a negative coronary CTA meantmediate discharge home. Invasive coronary angiographyA) occurred in 7.6% of the CT subjects (8.4% when the
ta are pooled and weighted) and 6.3% of the UC subjectsme when pooled and weighted). Hence, the absoluteference in the pooled weighted incidences was about 2%,th an odds ratio of 1.36, though with a lower confidenceit just above the threshold of statistical significance at3. Similarly, revascularization occurred in 4.1% of thesubjects (4.6% when pooled and weighted) and 2.6% ofUC group, which perhaps is not surprising given thatre was a slightly higher rate of ICA in the CT group.This meta-analysis did not attempt to compare length ofy or cost because of the methodological heterogeneity ofstudies, but the investigators point out that all of therce studies reported significant reductions in length ofy for the CT group. Coronary CTA is a quick procedure;st patients, having already established intravenous accessd received beta-blockers in the ED, are in and out of thenner room in 20 min. At our center, we usually have theding done before the patient makes it back to the ED.r ED physicians find this time-saving approach ex-mely helpful as they battle the time constraints sommon to any busy ED. Hulten et al. also point out thataddition to saving time, all the source studies thatluated ED cost reported significant cost savings. Theseta have supported the hypothesis that a CT strategy in theluation of ED chest pain saves time and money, and itsin this scenario is supported by recent guidelines (6,7).
Hulten et al. (5) conclude from their meta-analysis thatuse of coronary CTA to triage ED chest pain is safe,
nsistently reduces length of stay, and reduces ED cost, butmpared with traditional methods, is associated withhtly higher rates of ICA and revascularization. These
ISSN 0735-1097/$36.00http://dx.doi.org/10.1016/j.jacc.2013.01.002ferences were not statistically significant in any of therce studies, but they do reach the statistical thresholdth the increased number of subjects afforded by the
894 Weigold JACC Vol. 61, No. 8, 2013ta-analysis approach. Even though the demonstration ofs correlation does not prove that coronary CTA leads toA or revascularization, it is an intriguing finding worthmining more closely.It is important to point out that there were somenificant differences in methodology among these 4 stud-. The studies by Goldstein et al. (8) and the CT-STAToronary Computed Tomographic Angiography for Sys-atic Triage of Acute Chest Pain Patients to Treatment)
vestigators (9) were comparisons of CT not to clinicalage but to another imaging modality, namely single-oton emission CT (SPECT); no patients were to becharged without 1 of these 2 imaging tests (8,9). Perhapss is relevant: in CT-STAT, the 6-month cumulative ICAes in the 2 groups were nearly the same: 8% in the CTAup versus 7.4% in the single-photon emission CT group 0.78). This is different from ROMICAT II (Rule Outyocardial Ischemia/Infarction Using Computer Assistedmography) and ACRIN PA 4005 (CT Angiography forfe Discharge of Patients With Possible Acute Coronaryndromes) trials in which patients could potentially becharged without any testing. Hence, they were notceptible to the false-positive tests that plague someninvasive modalities. Goldstein et al. (8) and CT-STATwere also different in that the protocol required recom-nding additional testing after CT given certain criteria:ECT for any stenosis 25%, or even just a calcium score00, and ICA for any stenosis 70%. This very conser-ive approach may well have contributed to a higherheterization rate. Indeed, when those 2 studies areoved, the lower confidence limit of the odds ratio forA in the CT group nudges even closer to the nonsignif-nt level at 1.004. Hence, the association demonstratedtween CT and ICA is not exactly strong.That aside, Hulten et al. (5) point out that ICA andascularization contribute to the cost of care. This, gen-lly speaking, is true, but raises 2 other issues worthinting out. The first is particular to the studies of acuteest pain triage, which is that most patients (90%) inse studies did not undergo either ICA or revasculariza-n. In the evaluation of acute chest pain, the morequent source of cost is the diagnostic workup in the ED.this regard, the use of coronary CTA, compared to thestrategy, has consistently been shown in multiple
domized trials to reduce ED costs and to offset the costadditional ICA or revascularization.The second issue concerns those catheterizations andascularizations and is a more general point pertaining toalthcare costs. As we try to reduce healthcare spending,us not confuse quantity with quality. Whereas some
vocate broadly curtailing the use of all tests and proce-res in a nearly indiscriminate fashion, in fact the use ofse tools, and the costs associated with their use, are eithertified or unjustified depending on the circumstances of
Coronary CT Angiography in the EDparticular patients and clinical scenarios in which we usem. We should not seek to reduce the usage of resources
knmet for its own sake; rather, we should look for ways touce unnecessary usage. For this reason, comparing theidence of downstream resource utilization after coronaryA, though an interesting start, only touches the surfacethe issue. The more critical issue is whether thesecedures are being used appropriately. However, theestion of appropriateness was not examined by thista-analysis or any of the source studies and for a varietygood reasons. There are numerous and varied factors thaty into the decision to perform these procedures; clinicaltcome studies in this patient population would requirege numbers of subjects because event rates are low; andgnostic tests themselves do not exert any treatment effect,to truly test the effect of a diagnostic strategy on clinicaltcomes requires that treatments and therapies be strictlytated, per protocol, by the results of the test.Yet the data in hand may provide a little insight. In all ofsource studies, individually and as a whole, catheteriza-
ns prompted by coronary CTA were more often followedrevascularization than were catheterizations prompted byer approaches. Some would say that this indicates thatronary CTA drives revascularization, but this is not thee. The decision to revascularize is generally made basedthe findings of the invasive angiogram, not the nonin-ive test that preceded it. Instead, it would appear thaten the coronary CTA strategy does prompt an invasivegiogram, those angiograms provide a higher diagnosticld. For example, in ACRIN PA 4005, there wereuivalent rates of cardiac catheterization in the CTA andntrol arms (4%), but in the CTA group, the prevalence ofnificant disease on the invasive angiogram was 76%sus 44% in the traditional care group (10). Across the 4dies included in this meta-analysis, the diagnostic yield ofheterizations prompted by coronary CTA was highern for those prompted by usual care (54% vs. 41%), evenluding the requirements to test and catheterize in-ded in Goldstein et al. (8) and CT-STAT (9). Theseta suggest that the CTA strategy may help selecttients for ICA and thereby reduce the number ofnecessary catheterizations.If the CTA strategy reduces the number of unnecessaryheterizations, then why were there more revasculariza-ns in the CTA group? Perhaps the real question is whyre were fewer revascularizations in the UC group. All thetients in the CTA group essentially got an angiogram,d coronary CTA is exquisitely sensitive for the detectioncoronary disease. On the other hand, 94% of the patientsthe UC group never had their coronary arteries looked That is not necessarily a bad thing. But, are sometients in the UC group with obstructive coronary diseaseing missed and sent home without that diagnosis? Per-ps. Do they suffer a higher morbidity or mortality thanse detected and revascularized? Presumably that dependsthe extent and severity of their disease, but we will not
February 26, 2013:8935ow until we have much larger studies to find out. In theantime, the time pressures, budget constraints, and legal
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: email@example.com.
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Key Words: coronary angiography y coronary artery bypass graftsurgery y coronary computed tomography angiography y emergencydepartment y percutaneous coronary intervention.
895JACC Vol. 61, No. 8, 2013 WeigoldFebruary 26, 2013:8935 Coronary CT Angiography in the ED