Syncope in the ED: Distinguishing the Life-Threatening From the Benign -

Emergency Department Management of Syncope

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Table of Contents

About This Issue

Transient loss of consciousness from syncope is a very common presentation in the ED, and it often has a benign etiology. Although one-third of these patients are admitted to the hospital, the majority of them will be discharged with a symptomatic diagnosis of “syncope and collapse.” A structured approach to the history, ECG assessment, risk assessment, and appropriate testing will help identify patients with life-threatening processes that do require admission. This issue will review:

The physiologic basis for the 3 classifications: neurally mediated (reflex) syncope, orthostatic hypotension-caused syncope, and cardiac syncope

The most common life-threatening conditions that can present with syncope

The most helpful features to look for when differentiating seizure from syncope

Syncope mimics: neurologic, psychiatric, metabolic, and toxicologic

Identifying the highest risk historical features to guide disposition

Seven of the most commonly used clinical decision tools: how do they compare, how do they differ, and are any of them useful?

The particular concerns with elderly patients who present with syncope: falls, comorbid conditions, and underlying and undiagnosed conditions.

The tests that all patients need to have and the tests that should be ordered only when there are specific concerns.

Table of Contents
  1. Abstract
  2. Case Presentations
  3. Introduction
  4. Critical Appraisal of the Literature
  5. Etiology and Pathophysiology
    1. Neurally Mediated Syncope
    2. Orthostatic Hypotension-Mediated Syncope
    3. Cardiac Syncope
  6. Differential Diagnosis
    1. Seizure
  7. Prehospital Care
  8. Emergency Department Evaluation
    1. History
    2. Physical Examination
  9. Diagnostic Studies
    1. Electrocardiogram
    2. Laboratory Testing
    3. Echocardiography
    4. Imaging and Other Advanced Testing
  10. Treatment
    1. Clinical Risk-Stratification Tools
    2. Guidelines
  11. Special Populations
    1. Pediatric Patients
    2. Elderly Patients
  12. Controversies
    1. Admission of Elderly Patients
    2. Orthostatic Vital Signs
  13. Disposition
    1. High-Risk Patients
    2. Intermediate-Risk Patients
    3. Low-Risk Patients
  14. Summary
  15. Time- and Cost-Effective Strategies
  16. Acknowledgement
  17. Risk Management Pitfalls For Management of Syncope in the Emergency Department
  18. Case Conclusions
  19. Clinical Pathway for Emergency Department Evaluation of Patients Presenting With Transient Loss of Consciousness
  20. Tables and Figures
    1. Table 1. Classifications of Syncope, by Cause
    2. Table 2. Clinical Characteristics of Immediately Life-Threatening Conditions That May Present With Syncope
    3. Table 3. Syncope Mimics
    4. Table 4. Historical Features Suggesting Etiology of Syncope
    5. Table 5. Contraindications to Performing Carotid Sinus Massage
    6. Table 6. Electrocardiogram Findings Associated With Serious Cardiac Arrhythmias Within 30 Days
    7. Table 7. Low-Risk and High-Risk Features of Syncope, European Society of Cardiology
    8. Table 8. Clinical Decision Tools Used in Syncope Risk Stratification
    9. Figure 1. The Physiologic Basis of Syncope
    10. Figure 2. Type 1 Brugada Syndrome
    11. Figure 3. Epsilon Wave
    12. Figure 4. Electrocardiogram of Hypertrophic Cardiomyopathy
  21. References


Syncope is the transient loss of consciousness and postural tone, with spontaneous recovery. It accounts for approximately 1% of all emergency department visits and $5.6 billion in healthcare costs annually. In a very small subset of patients, syncope may be a warning sign for serious outcomes or death, but identifying these patients is challenging, as the emergency clinician must distinguish between life-threatening causes and the more common, benign etiologies. Low-yield and expensive testing is often performed, even for benign presentations. Much research on syncope is observational, and clinical decision rules frequently perform poorly in validation studies. This issue reviews the clinical and diagnostic findings that are useful for safely and efficiently identifying patients presenting to the emergency department with syncope.

Case Presentations

A 16-year-old girl is referred to the ED for a head CT after passing out in a doctor’s office…
  • As you review the chart, you note that the girl was in her dermatologist’s office, undergoing excision of a mole, when she became lightheaded and diaphoretic and passed out, without striking her head.
  • She was unconscious less than 1 minute and awoke with no confusion.
  • Because she passed out, the dermatologist told the parents that they should “go immediately to the ER for a CT.” You wonder if that’s really necessary in this case…
A 40-year-old man presents by EMS after what bystanders describe as a “seizure” while he is sitting in a chair…
  • EMS reports that bystanders told them that the man lost consciousness while sitting in a chair, and that he had generalized jerking of his extremities. When EMS arrived a few minutes later, they noted that his mental status was normal, but he was complaining of chest pain and shortness of breath.
  • The patient says that he underwent elective cholecystectomy 3 weeks ago, but denies abdominal pain or vomiting, and he says he has no other medical problems.
  • His vital signs are: blood pressure, 96/54 mm Hg; heart rate, 122 beats/min; respiratory rate, 24 breaths/min; temperature, 37°C; and oxygen saturation, 90% on 2 L nasal cannula.
  • The nurse asks if you want to place the patient on seizure precautions, but you’re not sure that’s his major underlying problem…
An 80-year-old woman presents to the ED after a fall…
  • The patient states she was walking to the bathroom when she found herself on the floor with right knee pain, and no recollection of how she got there. She currently has no other complaints.
  • Her vital signs are normal, and her past medical history is significant for diabetes, hypertension, and heart failure.
  • The x-rays ordered at triage are normal, and she is able to ambulate, but you wonder if there’s something else going on that you should look into before she leaves…

Clinical Pathway for Emergency Department Evaluation of Patients Presenting With Transient Loss of Consciousness

Clinical Pathway for Emergency Department Evaluation of Patients Presenting With Transient Loss of Consciousness

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Tables and Figures

Table 4. Historical Features Suggesting Etiology of Syncope

Table 1. Classifications of Syncope, by Cause
Table 2. Clinical Characteristics of Immediately Life-Threatening Conditions That May Present With Syncope
Table 3. Syncope Mimics
Table 5. Contraindications to Performing Carotid Sinus Massage

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Key References

Following are the most informative references cited in this paper, as determined by the authors.

5. * Brignole M, Moya A, de Lange FJ, et al. 2018 ESC guidelines for the diagnosis and management of syncope. Eur Heart J. 2018;39(21):1883-1948. (Guidelines) DOI:10.1093/eurheartj/ehy037

22. * D’Ascenzo F, Biondi-Zoccai G, Reed MJ, et al. Incidence, etiology and predictors of adverse outcomes in 43,315 patients presenting to the emergency department with syncope: an international meta-analysis. Int J Cardiol. 2013;167(1):57-62. (Meta-analysis; 43,315 patients) DOI: 10.1016/j.ijcard.2011.11.083

49. * Shen W-K, Sheldon RS, Benditt DG, et al. 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope. J Am Coll Cardiol. 2017;70(5):e39-e110. (Guidelines) DOI: 10.1161/CIR.0000000000000499

97. * Thiruganasambandamoorthy V, Sivilotti MLA, Le Sage N, et al. Multicenter emergency department validation of the Canadian Syncope Risk Score. JAMA Internal Medicine. 2020;180(5):737. (Prospective multicenter cohort study; 3819 patients) DOI: 10.1001/jamainternmed.2020.0288

98. * Probst MA, Gibson T, Weiss RE, et al. Risk stratification of older adults who present to the emergency department with syncope: the FAINT Score. Ann Emerg Med. 2020;75(2):147-158. (Prospective observational; 3177 patients) DOI: 10.1016/j.annemergmed.2019.08.429

Subscribe to get the full list of 117 references and see how the authors distilled all of the evidence into a concise, clinically relevant, practical resource.

Keywords: syncope, TLOC, electrocardiogram, ECG, vasovagal, hypotension, orthostatic, cardiac, seizure, dysrhythmia, palpitation, heart failure, Brugada, CSRS, Canadian syncope risk score, EGSYS

Publication Information

James Morris, MD, MPH, FACEP

Peer Reviewed By

Deborah Diercks, MD, MS, FACEP, FACC; Marc A. Probst, MD, MS, FACEP

Publication Date

June 1, 2021

CME Expiration Date

June 1, 2024    CME Information

CME Credits

4 AMA PRA Category 1 Credits™, 4 ACEP Category I Credits, 4 AAFP Prescribed Credits, 4 AOA Category 2-A or 2-B Credits.

Pub Med ID: 34008935

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