
==== Front
J Am Coll Emerg Physicians Open
J Am Coll Emerg Physicians Open
10.1002/(ISSN)2688-1152
EMP2
Journal of the American College of Emergency Physicians Open
2688-1152
John Wiley and Sons Inc. Hoboken

10.1002/emp2.13280
EMP213280
Original Research
Cardiology
Rapid outpatient evaluation for emergency department patients with intermediate risk chest pain safely reduces admissions
REUTER et al.
Reuter Quentin MD https://orcid.org/0000-0002-7045-7132
1 2 quentin.r.reuter@gmail.com

Lesh Nicholas MD 3
Reyes Michelle DO 1 2
Gothard David BS 2
Pallaci Michael DO 1 2
Weinstock Michael MD 4
1 US Acute Care Solutions Canton Ohio USA
2 Department of Emergency Medicine Summa Heath System Akron Ohio USA
3 Northeast Ohio Medical University Rootstown Ohio USA
4 Department of Emergency Medicine Adena Medical Center Chillicothe Ohio USA
* Correspondence
Quentin Reuter, Department of Emergency Medicine, Summa Heath System, 151 Forge Street, Akron, OH 44304, USA.
Email: quentin.r.reuter@gmail.com

10 9 2024
10 2024
5 5 10.1002/emp2.v5.5 e1328014 5 2024
04 2 2024
03 7 2024
© 2024 The Author(s). Journal of the American College of Emergency Physicians Open published by Wiley Periodicals LLC on behalf of American College of Emergency Physicians.
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc-nd/4.0/ License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.

Abstract

Objective

This study aims to assess the safety of an outpatient chest pain pathway (OCPP) for patients presenting to the emergency department (ED) with chest pain and a HEART score of 4 or 5.

Methods

This is a retrospective, observational, non‐inferiority study assessing the impact of the OCPP on the management and outcomes of ED patients with HEART score of 4 or 5. The study compared patients evaluated in the pre‐OCPP (January‒May 2018) and the post‐OCPP period (January‒October 2022). Data were collected via non‐blinded chart review. The primary outcome was the rate of acute myocardial infarction (AMI) and death in patients utilizing the OCPP compared to patients with HEART score 4 or 5 in 2018. Secondary outcomes included admission rates before and after the implementation of this pathway. Non‐inferiority of the post‐intervention study epoch for the AMI/death composite outcome was assessed via the two one‐sided tests (TOST), procedure.

Results

After implementing the OCPP, rates of patients with ED HEART score of 4 or 5 admitted from the ED decreased from 85.1% (605/711) to 74.1% (1239/1671) in 2022. Of the 432 total patients discharged in 2022, 237 (54.6%) patients were referred to emergent cardiology follow‐up via the OCPP. The 30‐day rate of AMI/death for patients discharged via the OCPP was 0.4% (1/237), as compared to 2.2% (8/368) in 2018. When compared to rates of AMI/death for all patients with HEART score 4 or 5 in 2018, outcomes for OCPP patients were found to be non‐inferior.

Conclusion

The OCPP resulted in non‐inferior rates of AMI/death in patients with HEART scores of 4 or 5 as compared to usual care.

source-schema-version-number2.0
cover-dateOctober 2024
details-of-publishers-convertorConverter:WILEY_ML3GV2_TO_JATSPMC version:6.4.8 mode:remove_FC converted:10.09.2024
Reuter Q , Lesh N , Reyes M , Gothard D , Pallaci M , Weinstock M . Rapid outpatient evaluation for emergency department patients with intermediate risk chest pain safely reduces admissions. JACEP Open. 2024;5 :e13280. 10.1002/emp2.13280

Meetings: ACEP, October 2023.

Supervising Editor: Bory Kea, MD, MCR.
==== Body
pmc1 INTRODUCTION

1.1 Background

Patients with chest pain account for over 6 million emergency department (ED) visits a year nationally and is a top reason for hospitalization or observation. 1 , 2 Specifically, patients presenting to the ED with chest pain and a HEART score of 4 or 5 have been admitted or observed for further risk stratification. This care management strategy is supported by national guidelines but does leave room for alternate care delivery strategies via shared decision making between ED providers and patients. 3

Rationale for rapid cardiac evaluation in ED patients with HEART scores of 4 or 5 stems from rates of major adverse cardiac events (MACE) originally published by Backus et al. 4 In this landmark study performed in the Netherlands, patients with a HEART score of 4‒6 had a MACE rate (myocardial infarction, death, or revascularization) of 16.6% at 6 weeks, justifying an aggressive and expedited management strategy.

While some definitions of MACE include all‐cause mortality, acute myocardial infarction (AMI), and coronary angiography and/or revascularization, including coronary artery bypass graft (CABG), it is clear that these clinical outcomes are not equivalent. 5 Most notably, the revascularization of stable obstructive coronary disease is not tantamount to death or AMI. Furthermore, revascularization of stable coronary disease offers little benefit in reducing future AMI, death, or hospitalizations. 6 , 7 , 8 Given the majority of MACE in the Backus study was coronary angiography and revascularization procedures, the rate of clinically relevant adverse cardiac events, namely, AMI and death, was relatively small. This notion is further supported by subsequent literature finding the rate of AMI and death in intermediate risk patients within 30 days, namely, those with HEART score of 4 or 5, approaches 1%‒2%. 9 , 10 , 11

1.2 Importance

Hospital crowding and ED boarding have been longstanding challenges to healthcare delivery, but in recent years, and notably since the COVID‐19 pandemic, these issues have evolved rapidly. The strain on EDs secondary to capacity challenges and evidenced by rising boarding hours and left without accessing care rates have steadily worsened during and after the COVID‐19 pandemic. 12 , 13 , 14 The need to make judicious use of inpatient resources and to ensure that patients receive the right care, at the right time, and in the right place has never been more critical.

Given the capacity strains faced by our local hospital system, and after reviewing the existing literature suggesting that the 30‐day rate of AMI and death in patients with a HEART score of 4 or 5 approaches 1%‒2%, ED and Cardiology leadership at our local institution determined that many of these patients could be safely discharged if close outpatient cardiology evaluation was available. On these premises, the outpatient chest pain pathway (OCPP) for patients with a HEART score of 4 or 5 was created as an alternative to hospital observation in the management of these patients.

1.3 Goals of this investigation

This study sought to evaluate the impact on patient safety and ED disposition at 30 days for patients with a HEART score of 4 or 5 utilizing the OCPP.

2 MATERIALS AND METHODS

2.1 Study design and setting

This was a retrospective, observational, non‐inferiority study evaluating the implementation of the OCPP. As this was a QI initiative and approved by the local hospital Medical Executive Committee as standard of care. The OCPP and its supporting literature were reviewed by the Institutional Review Board and received an exemption on 5/3/22.

Patients received care at one of our four ED facilities located in Northeast Ohio, including a tertiary care center with over 85,000 annual ED visits, a community hospital with over 33,000 annual ED visits, and two free standing EDs with roughly 21,000 and 9700 annual ED visits. Of note, the tertiary care and community facilities both utilize clinical decision units for the majority of ED chest pain patients who require admission.

2.2 Selection of participants

We evaluated and compared clinical outcomes of ED patients with HEART score 4 or 5 presenting to the ED between January and May 2018 and between January and October 2022. Initially, we planned to analyze only patient data from January to May in both 2018 and 2022, but we added patients from June to October 2022 period in order to have an adequate number of patients in the OCPP arm based on an a priori sample size calculation. Patients ≥18 years old were eligible for inclusion and were identified by having a HEART score of 4 or 5 documented by ED advanced practice provider (APP), resident physician, or attending physician. We chose 2018 to represent a “usual care” time period.

2.3 Intervention

Through collaboration between ED and Cardiology departments, we created the OCPP and launched this care pathway on January 1, 2022. The pathway utilizes rapid outpatient cardiology follow‐up for ED patients with chest pain and a HEART score of 4 or 5 as an alternative to hospital observation for further cardiac evaluation.

To qualify for entry into the OCPP, ED patients needed to have a HEART score of 4 or 5, as well as a non‐ischemic and interpretable electrocardiogram (ECG) (ie, no LBBB or paced rhythm) and a negative conventional troponin. If a patient's pain began <6h prior to evaluation, it was recommended that the patient have a repeat troponin prior to discharge. HEART score determination was left to the treating clinician. Documentation of HEART score for chest pain patients is a well‐adopted quality metric for our clinician group.

All HEART scores were calculated by the treating ED clinicians. Our data abstraction identified charts containing a documented HEART score of 4 or 5. If a patient with chest pain did not have a HEART score documented, they would not be included in our cohort. Within our EMR, HEART scores can be documented using a predesigned smart phrase, a HEART score calculation tool, or via free text. Our data acquisition strategy captured all three of these documentation formats. There is pre‐existing literature verifying the subjective nature and significant degree of inter‐rater variability inherent in the calculation of a HEART score. 15 , 16 We wished to ascertain the “real world” impact of the OCPP as thus we did not verify HEART score calculations by treating clinicians.

Patients with a HEART score of 3 or less were recommended to be discharged with primary care follow‐up. Patients with a HEART score or 6 or greater were recommended to be admitted for further cardiology evaluation. If a patient had a HEART score of 4 or 5, the patient could either be discharged with rapid outpatient cardiology referral (OCPP) or admitted for further cardiology evaluation. The decision to admit versus discharge was left to the treating clinician and patient, and it was recommended that shared decision making be utilized and documented. If the patient was discharged via the OCPP, they received a referral and were contacted urgently by the Clinical Access Center and were scheduled as expeditiously as possible for a cardiology appointment, with the goal being within 72 h of the ED visit. Of note, the American College of Emergency Physicians (ACEP) recommends follow‐up for discharged patients with chest pain to be completed within 1‒2 weeks. 17 Further cardiac testing and evaluation was left to the discretion of the cardiology clinician (Figure 1). During the intervention period, there was a department‐wide education initiative to convey the rationale and safety of the OCPP. Education included APP, resident, and attending physician presentations highlighting background literature on safety and instruction for utilizing the pathway.

FIGURE 1 Flow chart of the outpatient chest pain pathway disseminated to emergency department clinicians. ACS, acute coronary syndrome; AMI, acute myocardial infarction; PE, pulmonary embolism; LBBB, left bundle branch block.

2.4 Outcomes

The primary outcome was the rate of AMI and death for patients discharged via OCPP in 2022 compared to ED patients with a HEART score of 4 or 5 in 2018. We utilized a non‐inferiority assessment to compare these two cohorts. Secondary outcomes included admission rates of patients with HEART score of 4 or 5 in 2018 versus 2022, the type and results of cardiac testing performed for risk stratification for OCPP patients, the number of coronary catheterizations and revascularization procedures performed for OCPP patients, the number of OCPP patients with an elevated troponin, and the rate and timing of cardiology follow‐up evaluations for patients discharged via the OCPP.

AMI was defined as having an elevation in the troponin above the normal threshold of 0.03 and a final diagnosis of NSTEMI (non‐ST elevation myocardial infarction), STEMI (ST‐elevation myocardial infarction, or AMI (acute myocardial infarction). Conventional troponin I was used. If a patient had an elevated troponin, we assessed the final diagnosis documented in the discharge summary to better elucidate the type of cardiac injury and help exclude patients with elevated troponins secondary to etiologies other than acute coronary syndrome (ACS). All instances of AMI and death were adjudicated by the study authors. Specifically, once initially identified, instances of AMI/death were reviewed by one or more additional study authors and confirmed to have either elevated troponin above threshold and a discharge diagnosis consistent with acute myocardial ischemia, or death at 30 days.

2.5 Measurements

Data extraction methodology followed guidance published by Gilbert et al. 18 All data was collected via retrospective chart reviews using a standardized data retrieval form. All medical notes, medication administration records, laboratory test results, radiology reports and images, and operative and procedural records were available for review. The chart abstractors included three physicians and a medical student unblinded to the primary outcome. Prior to data extraction, the abstractors were adequately trained in the chart review methodology, including data element identification. A standardized abstraction form was utilized. Clear definitions for primary and secondary outcomes were established and applied. For example, the diagnosis of an AMI required a troponin level above normal threshold (>0.034 ng/mL) and a discharge summary or cardiology note documenting a diagnosis related to AMI, NSTEMI, or STEMI.  On patients with missing data, phone calls were made to ascertain follow‐up information. Patients were asked for the same data points as chart abstraction, including ED return visits, hospitalizations, occurrence of AMI, and other pertinent information. Three patients from 2018 had no follow‐up data available in the chart review and were excluded.

2.6 Data analysis

Data were imported into SPSSv25.0 software (IBM Corp.) and summarized by study epoch. Demographics including the age, gender, medical history, and baseline distribution of the HEART score were compared between the two epochs. Numeric age data were compared for mean equality via independent samples Student's t‐tests. Categorical data including HEART score were compared for distributional equality via Pearson chi‐square or Fisher's exact test depending on cell sample size distribution. Outcomes including the incidence of elevated troponin, AMI, death, and the composite of each together were summarized using frequencies and percentages. Pearson chi‐square or Fisher's exact tests were employed to compare the incidence rate for each outcome for equality between study epochs. A significant (p <0.05 via two‐sided testing) difference in the distribution of HEART scores at baseline was determined; hence, outcomes were summarized separately for each of the two HEART score values to investigate the potential influence of the distributional difference on our aggregated outcome comparisons. The rate of patients experiencing hospital readmission and ED repeat visits were similarly compared between study epochs. The non‐inferiority of the post‐intervention study epoch for the AMI/death composite outcome and the composite outcome including elevated troponin was assessed via the two one‐sided tests, two one‐sided test, procedure. For this procedure alpha was set at 5% and a non‐inferiority margin of 1% was assumed with the post‐intervention considered to be non‐inferior provided the upper limit of the 90% confidence interval was less than the 1% inferiority margin. Fisher's exact tests will be used when more than 20% of the cells in the bivariate frequency table have expected cell frequencies less than 5. 19

3 RESULTS

A total of 711 patients from 2018 (pre‐intervention) and 1671 patients from 2022 (with intervention) were analyzed to determine patient dispositions. From 2018 to 2022, the rate of patients admitted from the ED with a HEART score of 4 or 5 decreased from 85.1% (605/711) to 74.1% (1239/1671) in 2022. Of the 432 total patients discharged in 2022, 237 (54.6%) patients were referred to emergent cardiology follow‐up via the OCPP. Of the 711 and 1671 patients initially analyzed to determine disposition rates, 367/711 and 237/1671 (all of those within this cohort who were discharged via the OCPP) were analyzed to determine rates of AMI and death. See Table 1 for demographic data on the two patient cohorts. The two cohorts did not differ significantly in age, gender, or rates of comorbidities, nor did they have statistically different rates of 30‐day ED repeat visits or hospital readmissions. The proportion of patients with a HEART score of 4 was higher in 2022 as compared to 2018 (Table 1). Notably, 195/432 discharged patients in 2022 did not receive emergent cardiology follow‐up via the OCPP. Two of the 195 patients in this cohort (1.0%) had an AMI at 30 days and there were no deaths.

TABLE 1 Demographics, presenting HEART score, 30‐day repeat emergency department (ED) visits, and hospital readmission rates for 2018 and 2022 patient cohorts.

	Study epoch		
Variable/statistic	2018 (n = 368)	2022 (n = 237)	p‐value	
Age (years), mean (SD)	64.35 (12.57)	64.34 (12.63)	0.993	
Gender, n (%)	 	 	0.946	
Female	206 (56.0)	132 (55.7)	 	
Male	162 (44.0)	105 (44.3)	 	
Medical history, n (%) 				
CAD/MI	134 (36.4)	84 (35.4)	0.808	
CHF	58 (15.8)	29 (12.2)	0.228	
ESRD	7 (1.9)	4 (1.7)	1.000	
HEART score, n (%)	 	 	0.004	
4	235 (63.9)	178 (75.1)	 	
5	133 (36.1)	59 (24.9)	 	
Hospital readmission within 30 days, n (%)	34 (9.3)	19 (8.0)	0.583	
Repeat ED visit within 30 days, n (%)	52 (14.2)	24 (10.1)	0.137	
Note: Age was compared for mean equality via independent samples t‐test. ESRD was compared for distributional equality via Fisher's exact test. All other p‐values from chi‐square test of distributional equivalence.

Abbreviation: CAD, coronary artery disease; CHF, congestive heart failure; ESRD, end‐stage renal disease; MI, myocardial infarction; SD, standard deviation.

John Wiley & Sons, Ltd.

Of the patients referred via the OCPP, 61.9% (146/237) completed an in‐person cardiology appointment, 61 stress tests/coronary angiograms were performed, seven or which were positive. A total of nine heart catheterizations were performed with five patients receiving a stent and no CABG surgeries were performed. Seventy‐seven percent of discharged patients who completed their cardiology appointment did so within 1 week. One patient of the 237 OCPP patients had an AMI and none died at 30 days (rate of AMI or death at 30 days 0.42%). The patient with an AMI was diagnosed 28 days post the ED visits and had never followed up with cardiology but had attended two primary care appointments. In 2018, the rate of AMI/death for all HEART score 4 or 5 patients was 2.2% (8/368).

Using the 1% non‐inferiority margin we found the upper limit of the 90% confidence interval of the difference to be −0.3%.  Since this upper limit is less than the margin, we can conclude that there is non‐inferiority of the 2022 data for AMI/death at 30 days.

Similarly, the upper bound of the same 90% confidence interval for difference in elevated troponin/AMI/death at 30 days is 0.7%, which again is less than the margin of 1% and thus, we can conclude non‐inferiority of the 2022 outcomes compared to 2018. 20   Given the differing rates of HEART score of 4 versus 5 between the 2018 and 2022 cohorts, we completed non‐inferiority calculations on the HEART score 4 and 5 group individually and found consistent non‐inferiority of the 2022 outcomes compared to 2018 (Table 2).

TABLE 2 Outcomes at 30 days for 2018 versus 2022 patient cohorts.

	Study epoch		
Variable/statistic	2018 (n = 368)	2022 (n = 237)	p‐value	
Outcomes (30 days), n (%) 	
Elevated troponin	12 (3.3)	5 (2.1)	0.403	
AMI	7 (1.9)	1 (0.4)	0.157	
Death	1 (0.3)	0	1.000	
Composite—elevated troponin, AMI, death	13 (3.5)	5 (2.1)	0.315	
Outcomes by HEART score, n (%) 	
HEART score 4, n	235	178	 	
Elevated troponin	4 (1.7)	3 (1.7)	 	
AMI	3 (1.3)	1 (0.6)	 	
Death	1 (0.4)	0	 	
Composite—elevated troponin, AMI, death	5 (2.1)	3 (1.7)	 	
HEART score 5, n	133	59	 	
Elevated troponin	8 (6.0)	2 (3.4)	 	
AMI	4 (3.0)	0	 	
Death	0	0	 	
Composite—elevated troponin, AMI, death	8 (6.0)	2 (3.4)	 	
Note: p‐values from chi‐square tests for composite and elevated troponin. Death and AMI comparisons employed Fisher's exact tests.

Abbreviation: AMI, acute myocardial infarction.

John Wiley & Sons, Ltd.

4 LIMITATIONS

First, the study was conducted within one hospital system in Northeast Ohio and may not be extrapolatable to other clinical settings. Second, given this was not an RCT and only a small subset of HEART score of 4 or 5 patients were discharged using the OCPP, results cannot be extrapolated to all patients with a HEART score of 4 or 5. Furthermore, of the patients discharged, only 55% (237/342) received OCPP follow‐up, although rates of AMI/death in patients not receiving cardiology follow‐up was relatively low as well. Clinician discretion as to whether or not to discharge patients was incorporated into our pathway, which can be prone to practice variation and introduces the potential for selection bias. We chose 2018 to represent usual care but given the 4‐year gap in time, numerous other confounders, potentially related to COVID‐19, capacity challenges, and clinician turnover, could have confounded the results related to patient disposition. Finally, follow‐up information was not available for 3/368 patients in the 2018 cohort and none in the 2022 (post‐OCPP implementation), which may have affected the results.

5 DISCUSSION

The results of our study demonstrate how an OCPP for intermediate risk HEART score patients of 4 and 5 can be utilized to safely reduce admissions to the hospital. The percentage of patients admitted with a HEART score of 4 or 5 decreased from 85% to 74% between 2018 and 2022, respectively. Utilizing an OCPP our rates of AMI/death that was not inferior to standard of care for patients with a HEART score of 4 or 5 presenting to the ED with chest pain.

Our findings suggest that the OCPP appears to be safe leading to a rate of AMI/death at 30 days of 0.4%. This low rate of AMI/death, as well as the low rate seen in our 2018 cohort, is consistent with previous literature on true rate of AMI/death in this population of roughly 1%‒2%. 9 , 10 , 11 Of note, our rates of AMI/death fells comfortably within the 0%‒2.0% acceptable miss rate identified by the 2018 ACEP Chest Pain Guidelines. Our clinicians were able to safely and accurately identify a low‐risk cohort of patients with a HEART score of 4 or 5 who were appropriate for outpatient management. By the use of shared decision‐making conversation, patients were comfortable with the disposition decision and were capable of following up with cardiology on an expedited basis.

Despite this low rate of AMI/death, our findings do not support the use of an OCPP for every patient with a HEART score of 4 or 5. Only 14.1% (237/1671) of HEART score 4‒5 patients were referred via OCPP, representing a small portion of all comers and the potential for selection bias identifying a group that is inherently at lower risk of MACE. Moreover, the regional variations in population health, the medicolegal environment, and local healthcare resources may limit extrapolation of the OCPP to other clinical settings.

Our hospital uses a conventional troponin I assay for assessing cardiac injury. Many institutions have implemented high‐sensitivity troponins (hs‐trop) to evaluate patients in a more rapid fashion. We believe our findings are generalizable to health systems using hs‐T as this assay is more sensitive than conventional troponin I. As such, the use of hs‐trop arguably makes the pathway even more dependable and safe. 21 , 22 , 23

As capacity challenges continue to persist or even worsen, developing strategies to shift workups classically completed in the inpatient setting to the outpatient arena will be an important component to addressing ED and hospital overcrowding. It may benefit health systems to shift workups to outpatient evaluations for conditions such as chest pain, TIAs, syncope, dehydration, and mild infections. To do this, however, hospitals and provider groups must be willing and able to make specialist outpatient appointments, advanced imaging, and even infusion center treatments rapidly available to discharged ED patients. We cannot simply ‘discharge more patients’ safely, rather, we need systems and processes established as local standards of care to safely support this change in practice.

During the initial implementation and throughout the study period, we provided regular education to attending physicians, APPs, and residents on the pathway and rationale supporting its use. Despite this effort, only a small minority of patients were discharged via the OCPP. Significant effort must be put into implementation and adoption strategies to maximize the clinical impact.

Within our local healthcare system, an OCPP for ED patients with chest pain and a HEART score of 4 or 5 was associated with safe outcomes. In the 237 patients who were discharged with expedited outpatient follow‐up, there was one MI (0.4%) and there were no deaths. The OCPP can be a valuable tool for addressing capacity constraints within hospital systems, potentially reducing overcrowding in EDs and providing safe and efficient care for chest pain patients.

AUTHOR CONTRIBUTIONS

Quentin Reuter, Michael Pallaci, and Michael Weinstock conceived the study and designed the trial. Quentin Reuter, Michael Pallaci, and Michael Weinstock supervised the implementation of the intervention and subsequent data collection. Quentin Reuter, Nicholas Lesh, and Michelle Reyes undertook chart reviews and data collection. David Gothard provided statistical advice on study design and analyzed the data. Quentin Reuter drafted the manuscript, and all authors contributed substantially to its revision. Quentin Reuter takes responsibility for the paper as a whole.

CONFLICT OF INTEREST STATEMENT

The authors declare they have no conflicts of interest.

FUNDING INFORMATION

The authors received no specific funding for this work.

DATA AVAILABILITY STATEMENT

The entire deidentified dataset, data dictionary, and analytic code for this investigation are available upon request from the date of article publication by contacting Quentin Reuter, MD, at Quentin.r.reuter@gmail.com
==== Refs
REFERENCES

1 Bhuiya FA , Pitts SR , McCaig LF . Emergency department visits for chest pain and abdominal pain: United States, 1999‒2008. NCHS Data Brief. 2010;(43 ):1‐8.
2 Rui P , Kang K , Albert M . National Hospital Ambulatory Medical Care Survey: 2013 Emergency Department Summary Tables . https://www.cdc.gov/nchs/data/ahcd/nhamcs_emergency/2013_ed_web_tables.pdf
3 Gulati M , Levy PD , Mukherjee D , et al. 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: executive summary: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2021;144 (22 ):e368‐e454.
4 Backus BE , Six AJ , Kelder JC , et al. A prospective validation of the HEART score for chest pain patients at the emergency department. Int J Cardiol. 2013;168 (3 ):2153‐2158.23465250
5 Weinstock MB , Finnerty NM , Pallaci M . Time to move on: redefining chest pain outcomes. J Am Heart Assoc. 2019;8 (12 ):e012542.31184243
6 Maron DJ , Hochman JS , Reynolds HR , et al. Initial invasive or conservative strategy for stable coronary disease. N Engl J Med. 2020;382 (15 ):1395‐1407.32227755
7 Hochman JS , Anthopolos R , Reynolds HR , et al. Survival after invasive or conservative management of stable coronary disease. Circulation. 2023;147 (1 ):8‐19.36335918
8 Al‐Lamee R , Thompson D , Dehbi HM , et al. Percutaneous coronary intervention in stable angina (ORBITA): a double‐blind, randomised controlled trial. Lancet. 2018;391 (10115 ):31‐40.29103656
9 Sharp AL , Wu YL , Shen E , et al. The HEART score for suspected acute coronary syndrome in U.S. emergency departments. J Am Coll Cardiol. 2018;72 (15 ):1875‐1877.30286933
10 Spiegel R , Sutherland M , Brown R , Honasoge A , Witting M . Clinically relevant adverse cardiovascular events in intermediate heart score patients admitted to the hospital following a negative emergency department evaluation. Am J Emerg Med. 2021;46 :469‐475.33176952
11 Mark DG , Huang J , Kennedy CJ , et al. 60‐day major adverse cardiac events in emergency department patients with non‐low modified HEART scores. Am J Emerg Med. 2020;38 (12 ):2760.e5‐2760.e8.
12 Janke AT , Melnick ER , Venkatesh AK . Hospital occupancy and emergency department boarding during the COVID‐19 pandemic. JAMA Netw Open. 2022;5 (9 ):e2233964.36178691
13 Janke AT , Melnick ER , Venkatesh AK . Monthly rates of patients who left before accessing care in US emergency departments, 2017‒2021. JAMA Netw Open. 2022;5 (9 ):e2233708.36178693
14 Kilaru AS , Scheulen JJ , Harbertson CA , Gonzales R , Mondal A , Agarwal AK . Boarding in US academic emergency departments during the COVID‐19 pandemic. Ann Emerg Med. 2023;82 (3 ):247‐254.36681622
15 Niven WGP , Wilson D , Goodacre S , Robertson A , Green SJ , Harris T . Do all HEART scores beat the same: evaluating the interoperator reliability of the HEART score. Emerg Med J. 2018;35 (12 ):732‐738.30217951
16 Gershon CA , Yagapen AN , Lin A , Yanez D , Sun BC . Inter‐rater reliability of the HEART score. Acad Emerg Med. 2019;26 (5 ):552‐555.30428149
17 American College of Emergency Physicians Clinical Policies Subcommittee (Writing Committee) on Suspected Non‐ST‐Elevation Acute Coronary Syndromes , Tomaszewski CA , Nestler D , Shah KH , Sudhir A , Brown MD . Clinical policy: critical issues in the evaluation and management of emergency department patients with suspected non‐ST‐elevation acute coronary syndromes. Ann Emerg Med. 2018;72 (5 ):e65‐e106.30342745
18 Gilbert EH , Lowenstein SR , Koziol‐McLain J , Barta DC , Steiner J . Chart reviews in emergency medicine research: where are the methods. Ann Emerg Med. 1996;27 (3 ):305‐308.8599488
19 Bewick V , Cheek L , Ball J . Statistics review 8: qualitative data—tests of association. Crit Care. 2004;8 (1 ):46‐53.14975045
20 Walker E , Nowacki AS . Understanding equivalence and noninferiority testing. J Gen Intern Med. 2011;26 (2 ):192‐196.20857339
21 Twerenbold R , Costabel JP , Nestelberger T , et al. Outcome of applying the ESC 0/1‐hour algorithm in patients with suspected myocardial infarction. J Am Coll Cardiol. 2019;74 (4 ):483‐494.31345421
22 Chapman AR , Fujisawa T , Lee KK , et al. Novel high‐sensitivity cardiac troponin I assay in patients with suspected acute coronary syndrome. Heart. 2019;105 (8 ):616‐622.30442743
23 Nowak RM , Christenson RH , Jacobsen G , et al. Performance of novel high‐sensitivity cardiac troponin I assays for 0/1‐hour and 0/2‐ to 3‐hour evaluations for acute myocardial infarction: results from the HIGH‐US study. Ann Emerg Med. 2020;76 (1 ):1‐13.32046869
