Robert Bruce, an American Cardiologist, is considered the founder of exercise cardiology. He created the Bruce Protocol in the early 1960s. Sixty years later, cardiac stress testing has been pretty much the standard for screening low risk chest pain patients for coronary disease after a visit to the ED. It makes intuitive sense. If someone has narrowing of their coronaries and you get their heart rate up with a bit of exercise, you’re increasing demand; and if you see some ST changes or the person develops angina, well – they probably have a coronary lesion that needs to be fixed or medicated to prevent them from having an MI – right?
Well, it turns out that this 60 year long belief, that has led hundreds of thousands of people to angiograms, cardiac stents and CABGs, may be wrong. In this Journal Jam podcast we do a deep dive into the hugely complex literature of cardiac stress testing and see whether or not stress testing portends any benefit for patients who we assess in the ED for chest pain. The problem is – if stress testing doesn’t benefit our patients and isn’t a good screening test for preventing MIs, then what do we do with our low risk chest pain patients we see in the ED?
Cite this podcast as: Helman, A. Morgenstern, J., Spiegel R. Cardiac Stress Testing After Negative Workup for MI. Emergency Medicine Cases. April, 2019. https://emergencymedicinecases.com/cardiac-stress-testing/. Accessed [date]
Take Home Points on Cardiac Stress Testing After Negative ED Workup for MI
The miss rate for MI after an ED visit with nondiagnostic ECG and negative cardiac biomarkers is about 0.2%, not 2%. The patients who are sent for stress tests after a negative ED workup are extremely low risk to begin with.
Stress tests have a high false positive rate (as high as 80%) leading to unnecessary angiograms, cardiac stents and CABG. They are poor at identifying coronary artery disease and stress test studies in low risk chest pain patients suffer from inclusion bias. The sensitivity for 30 day MI and death is close to 0% in patients with a negative ED workup.
Stress echo and nuclear stress testing have slightly better accuracy than treadmill exercise stress testing in identifying coronary artery disease, but have never been shown to improve patient oriented outcomes after a negative workup in the ED.
Except in STEMI and unstable NSTEMI, cardiac stents do not have convincing evidence of benefit, and may be harmful. Patients with negative ED workups but positive stress tests usually go on to have angiograms and some get stents or CABG. While invasive management in patients with stable NSTEMI and unstable angina may decrease symptoms of angina and rehospitalization, they do not improve mortality rates, and may increase bleeding rates by a small but significant amount.
The 2018 ACEP clinical policy paper on suspected non ST elevation ACS asks: “In adult patients with suspected NSTEMI ACS in whom acute MI has been excluded, does further diagnostic testing for ACS prior to discharge reduce 30-day MACE?” Level B recommendation: “Do not routinely use further diagnostic testing prior to discharge in low risk patients in whom acute MI has been ruled out to reduce 30-day MACE.” Level C recommendation: “Arrange follow-up in 1 to 2 weeks for low-risk patients in whom MI has been ruled out. If no follow-up is available, consider further testing or observation prior to discharge.” They argue that limiting complex, expensive, and time-consuming testing can reduce patient cost, ED and hospital length of stay, and patient anxiety caused by unnecessary stress testing and potentially false-positive results, once adequate risk stratification and cardiac rule-out have occurred.
The American Heart Association guidelines recommends to work within your hospital system to establish an agreed-on approach to minimize medicolegal risk. Sit down with your cardiologists and hash this out, so that there is an agreed upon algorithm that makes sense, based on the literature. An algorithm for low risk chest pain patients that does not include routine stress testing is the most reasonable approach based on the current body of literature.
Efforts should be placed instead on patient education so they understand the risks of stress testing, and rational medical optimization for these patients.
After the recording of this podcast a multicenter retrospective analysis of 24,459 ED chest pain patients was published in Annals of EM.
They looked at 30-day major adverse cardiac events in adults with a chest pain diagnosis and troponin value who were discharged with an order for an outpatient cardiac stress test within 72 hrs of discharge. The 30-day rates of major adverse cardiac events were death (0.0%) acute myocardial infarction (0.7%), and revascularization (0.3%). 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).
Drs. Helman, Morgenstern and Spiegel have no conflicts of interest to declare.
References for cardiac stress testing
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Scheuermeyer F, Innes G, Grafstein E, et al. Safety and Efficiency of a Chest Pain Diagnostic Algorithm With Selective Outpatient Stress Testing for Emergency Department Patients With Potential Ischemic Chest Pain. Annals of Emergency Medicine. 2012;59(4):256-264.
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Froelicher VF, Lehmann KG, Thomas R, et al. The electrocardiographic exercise test in a population with reduced workup bias: diagnostic performance, computerized interpretation, and multivariable prediction. Veterans Affairs Cooperative Study in Health Services #016 (QUEXTA) Study Group. Quantitative Exercise Testing and Angiography. Ann Intern Med. 1998;128:(12 Pt 1)965-74.
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Napoli AM. The association between pretest probability of coronary artery disease and stress test utilization and outcomes in a chest pain observation unit. Academic emergency medicine : official journal of the Society for Academic Emergency Medicine. 2014; 21(4):401-7.
Lim SH, Anantharaman V, Sundram F, et al. Stress myocardial perfusion imaging for the evaluation and triage of chest pain in the emergency department: A randomized controlled trial. J. Nucl. Cardiol.. 2013; 20(6):1002-1012.
Frisoli TM, Nowak R, Evans KL, et al. Henry Ford HEART Score Randomized Trial. Circ Cardiovasc Qual Outcomes. 2017; 10(10).
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Fanning JP, Nyong J, Scott IA, Aroney CN, Walters DL. Routine invasive strategies versus selective invasive strategies for unstable angina and non-ST elevation myocardial infarction in the stent era. The Cochrane database of systematic reviews. 2016.
Khan SU, Singh M, Lone AN, et al. Meta-analysis of long-term outcomes of percutaneous coronary intervention versus medical therapy in stable coronary artery disease. European journal of preventive cardiology. 2018.
Mahler SA, Riley RF, Hiestand BC, et al. The HEART Pathway randomized trial: identifying emergency department patients with acute chest pain for early discharge. Circ Cardiovasc Qual Outcomes. 2015;8(2):195-203.
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.
Amsterdam E, Wenger N, Brindis R, et al. 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014;130(25):e344-426.
Natsui S, Sun BC, Shen E, et al. Evaluation of Outpatient Cardiac Stress Testing After Emergency Department Encounters for Suspected Acute Coronary Syndrome. Ann Emerg Med. 2019; in press
Other FOAMed Resources on Cardiac Stress Testing after Negative ED Workup for MI
EM Nerd on Sandu 2017 JAMA Internal Medicine paper
emDOCs on Risk Stratification and Stress Testing