CARDIOLOGY/ORIGINAL RESEARCH Evaluation of Outpatient Cardiac Stress Testing After Emergency Department Encounters for Suspected Acute Coronary Syndrome Shaw Natsui, MD, MPA; Benjamin C. Sun, MD, MPP; Ernest Shen, PhD; Yi-Lin Wu, MS; Rita F. Redberg, MD, MSc; Ming-Sum Lee, MD, PhD; Maros Ferencik, MD, PhD; Chengyi Zheng, PhD; Aniket A. Kawatkar, PhD, MS; Michael K. Gould, MD, MS; Adam L. Sharp, MD, MS* *Corresponding Author. E-mail: [email protected], Twitter: @adamlsharp. Study objective: Professional guidelines recommend 72-hour cardiac stress testing after an emergency department (ED) evaluation for possible acute coronary syndrome. There are limited data on actual compliance rates and effect on patient outcomes. Our aim is to describe rates of completion of noninvasive cardiac stress testing and associated 30-day major adverse cardiac events. Methods: We conducted a retrospective analysis of ED encounters from June 2015 to June 2017 across 13 community EDs within an integrated health system in Southern California. The study population included all adults with a chest pain diagnosis, troponin value, and discharge with an order for an outpatient cardiac stress test. The primary outcome was the proportion of patients who completed an outpatient stress test within the recommended 3 days, 4 to 30 days, or not at all. Secondary analysis described the 30-day incidence of major adverse cardiac events. Results: During the study period, 24,459 patients presented with a chest pain evaluation requiring troponin analysis and stress test ordering from the ED. Of these, we studied the 7,988 patients who were discharged home to complete diagnostic testing, having been deemed appropriate by the treating clinicians for an outpatient stress test. The stress test completion rate was 31.3% within 3 days and 58.7% between 4 and 30 days, and 10.0% of patients did not complete the ordered test. The 30-day rates of major adverse cardiac events were low (death 0.0%, acute myocardial infarction 0.7%, and revascularization 0.3%). Rapid receipt of stress testing was not associated with improved 30-day major adverse cardiac events (odds ratio 0.92; 95% confidence interval 0.55 to 1.54). Conclusion: Less than one third of patients completed outpatient stress testing within the guideline-recommended 3 days after initial evaluation. More important, the low adverse event rates suggest that selective outpatient stress testing is safe. In this cohort of patients selected for outpatient cardiac stress testing in a well-integrated health system, there does not appear to be any associated benefit of stress testing within 3 days, nor within 30 days, compared with those who never received testing at all. The lack of benefit of obtaining timely testing, in combination with low rates of objective adverse events, may warrant reassessment of the current guidelines. [Ann Emerg Med. 2019;74:216-223.] Please see page 217 for the Editor’s Capsule Summary of this article. Readers: click on the link to go directly to a survey in which you can provide feedback to Annals on this particular article. A podcast for this article is available at www.annemergmed.com. 0196-0644/$-see front matter Copyright © 2019 by the American College of Emergency Physicians. https://doi.org/10.1016/j.annemergmed.2019.01.027 INTRODUCTION The American College of Cardiology/American Heart Background Association recommends noninvasive cardiac stress testing Responsible for greater than 7 million annual visits to the within 72 hours after an acute myocardial infarction has emergency department (ED), chest pain remains the second been excluded by serial ECG and cardiac biomarker testing 3 most common reason for ED presentation of adults in the (class IIA recommendation). However, little is known of United States.1 A minority of these patients have acute the actual completion rates of guideline-recommended coronary syndrome and most do not even have heart disease. early outpatient stress testing and of the association of such However, stratifying this cohort is challenging, and the testing on patient outcomes. Three studies have examined inappropriate discharge of patients with high risk for acute early outpatient stress test completion in the United 4-6 coronary syndrome is associated with high morbidity.2 States. All were single-center studies with limited sample 216 Annals of Emergency Medicine Volume 74, no. 2 : August 2019 Natsui et al Evaluation of Outpatient Cardiac Stress Testing Editor’s Capsule Summary MATERIALS AND METHODS Study Design and Setting What is already known on this topic We conducted a retrospective study of eligible Based on limited data, professional guidelines encounters occurring from June 2015 through June 2017 recommend 72-hour cardiac stress testing after at 13 EDs of Kaiser Permanente Southern California, emergency department (ED) evaluations for which is an integrated health system providing health care suspected acute coronary syndrome. for greater than 4 million members. Kaiser Permanente What question this study addressed Southern California hospitals deliver care for greater than 1 The study uses existing data sets to determine million ED visits annually, with volumes of the study sites compliance with urgent outpatient stress testing and ranging from 25,000 to 95,000 ED visits per year. Of these 30-day incidence of major adverse cardiac events. ED visits, approximately 80% are from health plan members. One center has an emergency medicine residency What this study adds to our knowledge program. All sites use the same troponin laboratory assay In a highly selected cohort of 7,922 patients (one (Beckman Coulter Access AccuTnIþ3; Beckman Coulter, third of ED encounters were included) treated in a Brea, CA), and emergency physicians have the ability to well-integrated health care system, only 31% had order noninvasive cardiac testing as part of the discharge stress testing within 72 hours. There were no deaths; and follow-up plan. 0.9% had a 30-day major adverse cardiac event that was not associated with the timing of stress testing. Selection of Participants How this is relevant to clinical practice ED encounters were included for adult Kaiser Permanente health plan members (18 years) who were This study suggests that urgent outpatient stress discharged from the ED after an evaluation for chest pain, testing does not benefit low-risk patients with and who had a troponin laboratory test and an ED order negative ED evaluation results for acute coronary for outpatient cardiac stress test. We excluded patients who syndrome. had a do-not-resuscitate or hospice status, had an ED acute myocardial infarction diagnosis or troponin level of greater than 0.5 ng/mL, died in the ED, transferred from another hospital, or completed a stress test before discharge. Chest sizes, restricted inclusion to low-risk patients, and involved pain diagnosis was defined with International Classification targeted efforts (such as follow-up telephone calls) to of Diseases, Ninth Revision (ICD-9) codes (and ICD-10 maximize completion rates. Two of these studies assessed codes), and noninvasive cardiac tests were identified by associated major adverse cardiac events. One evaluated current procedural terminology codes (Appendix E1, them at 6 months according to stress test completion status available online at http://www.annemergmed.com). within that interval,4 whereas the other assessed adverse cardiac events in 30 days or death in 12 months according to stress test completion status within that 12-month Outcome Measures interval.5 Given that clinicians are most sensitive to the The primary outcome was the proportion of patients immediate outcomes after ED evaluation, these long-term who completed an early outpatient stress test within 72 major adverse cardiac events timeframes may provide only hours from ED discharge. Included in the primary limited insight to inform ED clinical decisionmaking and outcome was the proportion of patients who completed a disposition planning. stress test within 4 to 30 days or not at all. We also In 2016, Kaiser Permanente Southern California EDs measured 30-day incidence of major adverse cardiac events adopted a standard recommendation of using a History, (all-cause death, acute myocardial infarction, and ECG, Age, Risk Factors, and Troponin (HEART) pathway revascularization by percutaneous coronary intervention or for patients evaluated for suspected acute coronary coronary artery bypass grafting) as a secondary outcome to syndrome.7,8 Our objective was to describe rates of assess its relationship with early completion (Appendix E1, completion of early noninvasive cardiac stress testing and available online at http://www.annemergmed.com). associated 30-day major adverse cardiac events. Our study Midway through the study period in May 2016, all study aimed to specifically address several of these knowledge sites implemented decision support to capture HEART gaps by examining all outpatient stress testing from the ED scores and to incorporate this tool into routine ED care.7,8 in a large-volume, multicenter, community setting. We report the completion rates of stress testing stratified by Volume 74, no. 2 : August 2019 Annals of Emergency Medicine 217 Evaluation of Outpatient Cardiac Stress Testing Natsui et al this subgroup of encounters with documented low- (0 to cardiac events rates for patients completing noninvasive 3), moderate- (4 to 6), or high-risk (7 to 10) HEART testing within 72 hours compared with those who did not. scores. Mortality data were obtained