Evaluation, management, and disposition of low- and moderate-risk patients presenting to the emergency department with chest pain is a common clinical scenario for the emergency physician. It's something we deal with all the time, but simultaneously something that calls for continuous improvement.
Using validated decision pathways and risk stratification has greatly enhanced our approach over the past decade or so, but widespread variation persists as a function of a number of inherent limitations to this progress.
2022 ACC Expert Consensus Decision Pathway on the Evaluation and Disposition of Acute Chest Pain in the Emergency Department: A Report of the American College of Cardiology Solution Set Oversight Committee
Kontos MC, de Lemos, JA, et al.
J Am Coll Cardiol.
The recent release of the American College of Cardiology's Expert Consensus Decision Pathway on the Evaluation and Disposition of Acute Chest Pain in the Emergency Department, therefore, is notable not just for the recommendations contained within but also for its reflection upon the continued growth, evolution, and maturation of the specialty of emergency medicine. (J Am Coll Cardiol. 2022;S0735-109706618; https://bit.ly/3Di8tas.)
Comprehensive and considered, the ACC pathway harnesses not only the expert perspectives of emergency physicians who helped craft it, but also leverages a growing body of research and knowledge increasingly borne from emergency researchers. In all, the document addresses key questions facing emergency physicians and provides practical guidance to be applied at the point of care.
Skilled interpretation of serial ECGs is critical in evaluating potential acute coronary syndrome, and the ACC decision pathway brings a renewed and enhanced focus on ischemic ECG changes requiring referral for emergent coronary angiography. Importantly, there is recognition that the application of STEMI ECG criteria on a standard 12-lead ECG alone will miss a significant minority of patients who have acute coronary occlusion, an important nod to a growing understanding of the occlusion-nonocclusion MI paradigm. The OMI-NOMI concept is part of a new era in acute myocardial infarction recognition and management that has been strongly advocated for by some truly pioneering emergency physicians. (EMN. 2020;42:1; https://bit.ly/34hFe66.)
The list of STEMI equivalents and ECG findings consistent with acute and subacute myocardial ischemia that may benefit from emergent reperfusion demands vigilance and continued learning from the emergency physician. The list needs to be memorized, but—more broadly—emergency physicians must broaden their 12-lead interpretation skills to understand the full progression of ECG findings of occlusion and reperfusion. It can be a tall order to parse the subtleties of some of these electrocardiographic hints of danger. Fortunately, resources for continued ECG education (Dr. Smith's ECG Blog. Oct. 28, 2022; https://bit.ly/3fgQ8m9), both open access (ECG Wave-Maven. https://bit.ly/3ztFpvI) and paywalled (https://www.emedhome.com), have arisen to enhance ECG interpretation skills.
Of particular reminder within the recommendations are the de Winter sign (tall, prominent, symmetrical T-waves arising from upsloping ST-segment depression >1 mm at the J-point in the precordial leads), hyperacute T-waves (broad, asymmetric, peaked T-waves that may be seen in early STEMI), and Wellens syndrome (a clinical syndrome characterized by biphasic or deeply inverted and symmetric T-waves in leads V2 and V3 and recent anginal symptoms). Each of these has held its moment in the EM limelight over the past few years, and their recognition and subsequent action are critical in the battle to salvage myocardium.
The consensus decision pathway recommends the use of the Sgarbossa criteria or the Smith-Modified Sgarbossa criteria (there's an app for that: MDCalc; https://bit.ly/3SGOo3i) in the setting of LBBB or ventricular-paced rhythm. aVR ST-segment elevation, ST-segment depression, and inverted T-waves are all also highlighted for their importance in interpreting the ECG for changes suggestive of ACS.
There is also an important reminder to review the prehospital ECG, a recognition of the fact that subtle (or even overt) signs of ischemia may resolve prior to ED evaluation. While prehospital recognition of STEMI is known to decrease reperfusion times and improve outcome, paramedic engagement in ECG interpretation is similarly important in evaluating NSTE-ACS. (J Emerg Med. 2014;46:202; https://bit.ly/3WccDJC.) Another study found that 60 percent of diagnostic ST changes resolved prior to hospital arrival, marking ample opportunity for the prehospital 12-lead to influence clinical care. (Ann Emerg Med. 2022;S0196-064400579; https://bit.ly/3DjI38r.)
Once an ECG has been determined to be nonischemic, the expert consensus decision pathway is focused on patient management and disposition using high-sensitivity cardiac troponin I (hs-cTnI) assays. The document plainly states its support for a transition to hs-cTn assays, which—they argue—offer important advantages for the rapid evaluation and disposition of chest pain in the ED and allow optimal patient care. High-sensitivity troponin represents a relatively new diagnostic capability in U.S. emergency departments, despite more than a decade of use in European and Australasian hospitals. (EMN. 2012;34:1; https://bit.ly/3gSgNX5.) Compared with older-generation assays, hs-cTn assays are more sensitive and more precise. Increased sensitivity allows exclusion of even minor cTn elevations, permitting rule-out of MI with a single blood draw when the hs-cTn value is very low and symptoms have been present for three hours or more.
If your institution has yet to institute high-sensitivity troponin, the pathway advocates for transition. It's not a flippant undertaking, though. Thoughtful hs-cTn implementation strategies certainly reduce length of ED stays, admission and stress testing rates, and costs—without an increase in adverse cardiovascular outcomes—but demand multidisciplinary collaboration and must be paired with a validated clinical pathway to harness their optimal benefit. High-sensitivity troponin can generally be used as part of a 0/1 or 0/2-hour algorithm, or via the High-STEACS 0/3-hour algorithm. In short, patients may be ruled out by having a very low hs-cTn at baseline (if chest pain onset is three hours or longer) or by having values below a specified threshold and no more than a very small change (“delta”) between serial measurements. Implementation of hs-cTn assays in conjunction with a clinical decision pathway can reduce ED “dwell” times and increase the proportion of patients with chest pain who can safely be discharged without additional testing.
While hs-cTn increases the percentage of patients discharged from the emergency department without need for further testing, approximately one in four patients presenting with possible ACS may be assigned to an intermediate-risk group, either by minimally elevated hs-cTn or via concomitant application of a validated risk score, such as the modified HEART or EDACS score. (Though, notably, the use of these risk scores is not really recommended alongside hs-CTn because the increased safety will be minimal but will come with significant diminishment of operational returns from assay implementation.) Some of these patients will go on to be diagnosed with acute coronary syndrome at their index visit, but the rest may benefit from enhanced diagnostic testing, as their risk of MACE or death at 30 days is markedly higher than their low-risk counterparts. Here, the pathway authors make a case for the use of coronary CTA.
Coronary CTA (CCTA) is an accurate, noninvasive method for diagnosing CAD. CCTA and its utility in the emergency department, though, have attracted skepticism from some in the emergency medicine community. (First10EM. Nov. 4, 2019; https://bit.ly/3DIV10M.) Compared with functional testing modalities, CCTA may be more rapidly available to patients undergoing evaluation in the ED, making it an attractive test to provide a timely evaluation of the presence and severity of CAD in intermediate-risk patients so that decisions regarding disposition and management can be expedited.
Unfortunately, what limited data exist on this population have failed to show much benefit. Furthermore, CCTA requires significant logistical support from within and outside the emergency department, including heart rate control with beta blockade (to optimize the patient's heart rate to limit motion artifacts in the coronary arteries) and radiologists trained in CCTA interpretation. Nonetheless, the decision pathway recommends that coronary CTA, when available, should be considered the preferred noninvasive test for patients presenting to the ED with possible ACS who do not have known CAD, a recommendation that may lead to significant ED operational impact, especially as CCTA availability spreads.
The ACC pathway brought together representatives from emergency medicine, cardiology, nursing, laboratory medicine, hospital medicine, internal medicine, family medicine, radiology, health systems administrators, insurance company representatives, industry representatives, and government regulators to help research, derive, and develop recommendations and guidance in a modern world of enhanced ECG interpretation, high-sensitivity troponin assays, and increasingly available noninvasive testing.
Though little fanfare seemed to accompany its release, it's likely that this document will guide ED disposition of chest pain in the years to come—and be the standard with which management may be compared. Evaluating patients presenting to the emergency department with chest pain grows increasingly complex, as does the diagnostic armamentarium available. Emergency physicians would be prudent to familiarize themselves with the tools at their disposal and to advocate for parity where resources may fall short.
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The Smith-Modified Sgarbossa Criteria
- Concordant ST elevation ≥1 mm in leads with a positive QRS complex
- Concordant ST depression ≥1 mm in V1-V3
- ST Elevation at the J-point, relative to QRS onset, is at least 1 mm AND has an amplitude at least 25% of the preceding S-wave. An ST/S ratio of 0.20 is also very high and almost as specific as a 0.25 ratio.
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Dr. Pescatoreis clinical faculty and an attending emergency physician at Einstein Healthcare Network in Philadelphia. Follow him on Twitter@Rick_Pescatore.
The author, faculty, and planners have no relevant financial relationships with any ineligible organization regarding this education activity.