Article, Cardiology

The utility of the triage electrocardiogram for the detection of ST-segment elevation myocardial infarction

a b s t r a c t

Introduction: Current AHA/ACC guidelines on the management of ST-elevation myocardial infarction suggest that an ECG is indicated within 10 minutes of arrival for patients arriving to the Emergency Department (ED) with symptoms concerning for STEMI. In response, there has been a creep towards performing ECGs more frequently in triage. The objectives of this study were to quantify the number of triage ECGs performed at our institution, assess the proportion of ECGs performed within current hospital guidelines, and evaluate the rate of STEMI detection in triage ECGs.

Methods: A retrospective chart review of all emergency department patients presenting over a period of 8 days who had a triage ECG performed. Cases of bradycardia or tachycardia were excluded. Data collection included patient demographics, presenting complaint, cardiac risk factors, troponin values, and final diagnosis. Summary statistics are reported in a descriptive manner.

Results: During the study period, 538 patients had a triage ECG for possible STEMI with no STEMI identified and 16 NSTEMI diagnoses (confirmed as positive troponins following ED assessment). Sixty-three (11.7%) patients did not meet internal criteria for a triage ECG. A NSTEMI ED diagnosis was identified in 3% of patients who met internal triage ECG criteria and 1.6% who did not meet criteria (p = 0.29). A cost analysis was performed using an average of 50 STEMI cases diagnosed in our ED per given year. Current institutional ECG billing rates for ECGs performed and interpreted is $125 per ECG, providing an estimated triage ECG charge to detect one STEMI at $54,295.

Discussion: This retrospective study of 538 triage ECG’s performed over an 8 day period identified no STEMIs and 16 NSTEMIs. A very large number of ECGs were done at triage overall and included patients who do not meet our own hospital criteria. Given the extremely low yield and high associated charges, current guidelines for triage ECG for identifying a possible STEMI should be reviewed.

(C) 2018

Introduction

ST-segment elevation myocardial infarction is associated with a 10% in-hospital mortality rate [1]. Research has shown early treatment including percutaneous coronary intervention (PCI) for STEMIs increases the likelihood of survival [2,3]. These findings have helped set current practice guidelines, with high level

? This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

?? Society of Academic Emergency Medicine Annual Meeting, May 15, 2015, San Diego, CA.

* Corresponding author: Emergency Department, 2799 W Grand Blvd, Detroit, MI 48202, USA.

E-mail address: [email protected] (S. Noll).

recommendations, from the American Heart Association-American College of Cardiology (AHA/ACC). Guidelines aim to reduce the time of first medical contact (FMC) to PCI and restoration of flow in coronary vessels [4].

Current AHA/ACC guidelines for STEMI management recommend performing an ECG at the site of FMC in patients with symptoms con- sistent with STEMI [4]. Furthermore, the current European Society of Cardiology guidelines include performing and interpreting an ECG with a target of b10 min [5]. The Centers for Medicare and Medicaid Services has defined national quality measures based on door to balloon time (DTB) time and emergency department (ED) arrival to electrocardiogram (ECG) time. In patients who arrive with chest pain and are at risk of a possible STEMI, the CMS target for ED arrival to ECG is 10 min [6]. Emergency physicians and cardiologists have

https://doi.org/10.1016/j.ajem.2018.01.083

0735-6757/(C) 2018

1772 S. Noll et al. / American Journal of Emergency Medicine 36 (2018) 17711774

extensively studied these target times in an effort to meet recom- mendations [7,8].

Many institutions have developed nurse driven Triage protocols to improve time to ECG performance at the point of FMC. These protocols are aimed at identifying all STEMIs as soon as possible at ED presenta- tion. As a result, there has been a tendency towards performing ECGs more frequently in triage, including at nurse discretion [9-11]. These ad- vanced triage protocols are implemented with a goal to decrease the DTB time [12,13]. Studies show that these broad efforts to rapidly obtain ECGs in the ED have led to an overall decrease in DTB times but require increased training and personnel [14,15]. Some have considered performing an ECG on every patient presenting to the ED, regardless of the clinical presentation, but found that this would divert medical equipment and strain personnel-related resources [16]. Moreover, previous investigative teams have acknowledged that performance of the ECG is not the same as its effective interpretation [17,18]. ED physi- cians miss 1 in 8 ACS related ECG changes and up to 6% of STEMIs thus protocols will only succeed if the ECG performed is both promptly and correctly interpreted by a well-trained health professional [17,18]. This can sometimes be challenging in a large urban ED, where the ECG interpreter may be involved in another critical procedure or encounter [16]. Few have addressed ECG interpretation and the amount of re- sources needed for this optimization including the actual Cost benefit of these protocols.

Objectives

The primary objectives of this study were to quantify the number of triage ECGs performed, assess the proportion of triage ECGs performed within current hospital guidelines, and evaluate the rate of STEMI detec- tion in triage ECGs. Secondary objectives were to evaluate nursing staff perspectives concerning their clinical ability to detect STEMIs and deter- mine the cost effectiveness of current triage ECG testing practices.

Methods

This was a single center retrospective observational study of all pa- tients presenting to our hospital, an urban tertiary care referral hospital ED who had an ECG performed at triage over an 8 day period in 2013. This study was approved by our hospital institutional review board.

At our hospital, patients who present to the emergency department have a triage ECG performed when they meet local triage ECG guide- lines. Triage ECGs are reviewed by emergency physicians promptly to assess for acute changes concerning for STEMI that would require im- mediate intervention (Fig. 1: Triage indications).

Patients were excluded from the current study if the ECG revealed bradycardia (heart rate b50 beats per minute) or tachycardia (heart rate N110 beats per minute). This exclusion criterion was selected to ac- count for the possibility that the ECG was indicated for dysrhythmias and not for concern regarding diagnosing STEMI (Fig. 2: Flow diagram). Data was collected with regards to patient demographics, presenting complaint, cardiac risk factors, Troponin assessment and results, final ED diagnosis, institutional charges for ECG procedures, reimbursement

rate, and annual average STEMI rate.

Age > 30 years complaining of non-traumatic chest pain or discomfort

Age > 50 years with one or more of the following:

Chest pain Syncope Palpitations Shortness of breath

Epigastric pain/discomfort Diaphoresis

nausea or vomiting

Triage Nurse deems ECG necessary

Fig. 1. Triage indications. Clinical indications for triage ECGs to be performed.

EMR search for triage ECGs performed over 8 day period

608 ECGs performed

Included Cases (n = 538)

Triage ECG identified STEMI (n = 0)

ED diagnosis of NSTEMI (n = 16)

Fig. 2. Flow diagram. Inclusion criteria of ECG cases.

Excluded Cases (n = 70):

-HR<50 (n = 4)

-HR>110 (n = 66)

To further evaluate nursing perspectives on Clinical concerns for STEMI and the departmental guidelines, a voluntary multiple-choice survey was administered to the triage nursing staff. The survey contained 6 questions that asked the ED Triage nurses to identify their experience and perspectives concerning their own clinical evaluation in identifying STEMIs at triage (Supplemental e1: Nurse Survey Questionnaire).

Data was summarized using descriptive statistics. A p-value of 0.05 was considered statistically significant. All analysis was performed using SAS 9.3 (Cary, NC). Additionally, Fisher’s exact test was used to compare rates of NSTEMI between patients that met our internal ECG criteria and those that did not.

Results

During the study period a total of 608 triage ECGs were performed, of which 70 were excluded. Of the 538 remaining triage ECGs, there were no STEMIs identified at triage and 16 cases in which the ED diag- nosis was NSTEMI. Baseline characteristics of patients who had a triage ECG are reported (Table 1: Baseline characteristics). The most common symptoms prompting an ECG were: chest pain (46.3%), dyspnea (39.4%), nausea and vomiting (34.0%), epigastric pain (18.6%), lightheadedness or dizziness (13.2%); and weakness (12.6%). ED course characteristics following triage ECG, we report the final ED diagnosis, ECG interpretations, troponin ordering/elevations, and ED dispositions for those who had a triage ECG are also noted (Supplemental e2: Graph). No patients STEMI recognized at triage with a triage ECG and 3% of all patients with a triage ECG were diagnosed with NSTEMI. While in the ED, one patient progressed to have ECG changes consistent with STEMI although the initial triage ECG did not meet STEMI defini- tion guidelines.

Sixty-three (11.7%) patients did not meet local guidelines for triage

ECG. An ED diagnosis of NSTEMI (recognized as the ED provider’s clini- cal diagnosis following triage ECG) was identified in 3% of patients who met internal triage ECG criteria and 1.6% who did not meet these criteria (p = 0.29). One hundred thirty-four (24.9%) patients did not have any cardiac troponin ordered by the treating clinician after initial triage ECG was performed.

A cost analysis was performed based on an average of 50 STEMI cases diagnosed per given year in our ED. Using 2016 institutional

S. Noll et al. / American Journal of Emergency Medicine 36 (2018) 17711774 1773

Table 1

Baseline characteristics. For patients who had a triage ECG performed.

Median age (years)

58 (IQR 49-69)

Gender n (%)

Male 245 (46)

Female 293 (54)

Race n (%)

African American 412 (77)

American Indian 1 (b1)

Asian 7 (1)

Caucasian (non-Hispanic) 54 (10)

Hispanic 1 (b1)

Other 26 (5)

Unknown 37 (7)

known CAD n (%)

being performed even though they have a low likelihood of having STEMI detected at triage.

In this study, over a limited time of 8 days, we found over 500 triage ECGs were performed at our institution. These triage ECG’s were reviewed immediately by emergency physicians to rule out the need for Cardiac interventions. This review results in ED physicians being interrupted multiple times an hour to rapidly interpret the ECG as re- ported in literature. These interruptions may cause distraction that lead to failure to return to interrupted tasks, delays in other patient care and to diagnostic and therapeutic errors [11]. Other researchers have considered the addition of trained personnel at the door but this was deemed too costly [20]. Glickman et al. developed a prioritization rule for obtaining immediate ECGs at triage to identify STEMI. This mod-

ified protocol however led to approximately 8% of STEMI patients being

Risk factors for CADa

118 (22)

n (%)

missed [9]. While the simplified protocol age dependent rule had a sen-

0 63 (12)

1-2 292 (54)

N3 65 (12)

Medications n (%)

ASA 175 (33)

Plavix 36 (7)

Nitrates 38 (7)

Presenting symptoms n (%)

Chest pain 249

Shortness of breath 212

Nausea/vomiting 183

Epigastric pain 100

Dizziness/lightheadedness 71

Weak/weakness 68

Not feeling well/Ill 42

Shoulder/Arm pain 40

Back pain 39

Palpitations 37

Syncope 26

Diaphoresis 26

jaw pain 17

Hypertension 7

a Hypertension, diabetes mellitus, hyperlipidemia, smoker, obesity, family history of CAD.

charges for ECGs performed and interpreted at $125 per ECG, the esti- mated triage ECG charge to detect one STEMI is $54,295. Extra ECG charges for the approximately 25% of triage ECGs in which no subse- quent troponin was ordered were estimated to be $678,675 per year.

cost estimates do not include Opportunity costs related to triage ECG performance and immediate physician interpretation. We estimate an added 9 min are spent obtaining an ECG in triage [19], which does not include the additional time required for a staff physician to review and interpret it.

The nurses working in triage at our institution are generally experi- enced, with 52% having N10 years of work experience in triage (Supple- mental e3: Graph). Sixty-one percent of nurses reported that they thought they could clinically identify the need for a triage ECG in pa- tients with a possible STEMI N70% of the time, without consulting triage guidelines. Additionally 42% of the nursing staff reported performing N50% of their triage ECGs based on their own clinical evaluation regard- less of triage guidelines (Supplemental e4: Graph). However, our study found that in the 538 triage ECGs performed there were no STEMIs iden- tified regardless if triage guidelines to perform ECG were met.

Discussion

Our retrospective single center observational study found that a large number of triage ECGs were being performed with low yield for STEMI identification or NSTEMI diagnosis. During the study period, no true STEMIs were identified in triage and only 3% of patients had a final ED diagnosis of NSTEMI. These results indicate that a significant number of low-risk possible AMI patients are having emergent ECGs

sitivity of 91.9% (95% CI 90.9%-92.8%) and a negative predictive value of 99.98% (95% CI 99.98%-99.98%), it maintained the use of clinical judg- ment to determine need for triage ECG [9]. Given the potential of miss- ing 8% of STEMI’s using the Glickman protocol, it remains that the triage ECG will potentially still be obtained based on the fear of a missed STEMI. More than 10% of ECGs, in our study, were performed based on nursing gestalt without objective signs or symptoms suggestive of ACS. This ultimately contributes to increased numbers of triage ECGs leading to interruptions for interpretation of non-critical ECGs. Further- more, a quarter of the patients in our study who had ECGs performed in triage likely had a low suspicion of ACS as the treating clinicians did not subsequently order troponins. We assume that this was likely related to lack of concern for ACS or cardiac ischemia. The patients’ presenting ED symptoms that augured a triage ECG were quite varied with less than half having some chest pain. In addition, there was a very low incidence (22%) of coronary artery disease (CAD) and the majority of our patient population (66%) had two or less risk factors for it. Lastly, 51% of our studied patients were discharged home after ED evaluation.

These findings are significant as the practice of medicine transitions

to focus towards cost-effectiveness and the appropriate utility of re- sources (such as the choosing wisely campaigns). It is a constant chal- lenge for the US to triage the 8 million annual ED visits related to chest pain or suspected cardiac problems and quickly decipher the critical pa- thology [21,22]. Electrocardiography is only one tool of many to help with this clinical-decision making and although the testing itself may be an inexpensive resource, the time associated with interpretation and sensitivity for ACS greatly affects its utility. Additionally, relying on ECGs as the lone tool to diagnose STEMI at the point of FMC is asso- ciated with increased inaccurate diagnoses of STEMI and accounts for approximately 25% of patients with insignificant CAD found at cardiac catheterization [23,24].

Although electrocardiography can rapidly detect STEMIs, STEMI rates are declining in the US to b25% of all ACS cases [25]. Our ED has an average of 50 STEMI cases/year, which is consistent with the estimat- ed incidence of 50-77/100,000 cases of STEMI annually in the US [26]. For the combined efforts of emergency medicine technicians, nurse as- sistants, nurses, and staff physicians to identify STEMIs, resource utiliza- tion should be better characterized.

Limitations

We acknowledge several limitations of this single center, retrospec- tive study. We have relatively small sample size and a limited duration for the study period. Furthermore, our data was retrospectively collect- ed based on ED diagnoses and thus, the hospital discharge diagnoses may have differed. The retrospective nature of this study also limits our ability to understand the clinicians’ diagnostic process and thinking. In addition, our exclusion criteria (bradycardia and tachycardia) may have missed more patients with NSTEMI diagnoses. Additionally, no STEMIs were identified in the initial review of ECG data collected. Re- imbursement rates and opportunity costs were calculated based on

Declaration of interest“>1774 S. Noll et al. / American Journal of Emergency Medicine 36 (2018) 17711774

values available to the ED and research team and do not necessarily characterize all insurance and in-hospital charges. Finally, our voluntary online nursing survey could have included response biases.

Conclusion

This single center study of emergency department triage ECGs, iden- tified a large number of ECG’s performed at triage for immediate evalu- ation and interpretation with a low yield for identification of STEMI. As the yield is low but the Associated costs with this practice are high, cur- rent guidelines for triage ECG for possible STEMI should be reviewed and more focused. When developing criteria for obtaining triage ECGs, consideration should be given to more cost effective plans.

Further studies are needed that include measurements of time away from tasks, medical care interruptions, costs regarding missed STEMIs (including CMS fines), evaluation of errors and mistakes with interrupted tasks, and studying pre-hospital ECG interpretation as com- pared to triage ECG obtaining and subsequent interpretation. The re- sults of these would help develop triage ECG protocols with optimal sensitivity and a minimally accepted miss rate for STEMI.

Declaration of interest

None.

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi. org/10.1016/j.ajem.2018.01.083.

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