CRACKCast E203 – Syncope

In CRACKCast, Podcast by Dillan RadomskeLeave a Comment

Syncope is one of the core presentations we see in the ED. While benign for many patients, there are several critical diagnoses we need to rule out in the syncopal patient. This episode features Chloe Labrie, a Family Medicine Resident with a keen interest in EM.

Shownotes: PDF Here

Core Questions:


Rosen’s in Perspective

Syncope is a “sudden transient loss of consciousness with a loss of postural tone,” typically with an immediate return to baseline afterwards. This is a common ED presentation. Causes are typically benign, however there are some killers that can hide in these presentations. History, physical and ECG are your key diagnostic modalities. 

The final common pathway resulting in syncope is bilateral cortical dysfunction and/or brainstem dysfunction (esp reticular activating system, secondary to hypoperfusion. Loss of consciousness causes the loss of postural tone and bam, syncope. Less severe hypoperfusion can cause feelings of presyncope, which we consider to be on the same continuum of disease. 

There are 3 major classifications of syncope: vasovagal, orthostatic hypotension, and cardiovascular. Other general causes and mimics include seizures, hypoglycemia, toxins, metabolic derangements, hyperventilation, psychiatric causes, and some primary neurologic conditions. 

[1] List 10 life-threatening causes of syncope 

  1. Myocardial infarction
  2. Dysrhythmias
  3. Thoracic aortic dissection
  4. Critical aortic stenosis
  5. Hypertrophic cardiomyopathy
  6. Pericardial tamponade
  7. Abdominal aortic aneurysm
  8. Massive pulmonary embolism
  9. Subarachnoid hemorrhage
  10.  Stroke (cerebrovascular accident)
  11.  Toxic-metabolic derangements
  12.  Severe hypovolemia or hemorrhage
  13.  Ruptured ectopic pregnancy
  14.  Sepsis

(Adapted from Box 12.3, Rosen’s 9th Ed.)

[2] List 10 medications that can precipitate syncope 

 In true CRACKCast fashion, there are way more than 10 (See Box 12.2 in Rosen’s 9th Edition).

  1. Cardiovascular agents
  2. Beta blockers
  3. Vasodilators—beta blockers, calcium channel blockers, nitrates, hydralazine, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, phenothiazines, phosphodiesterase inhibitors
  4. Diuretics
  5. Central antihypertensives (eg, clonidine, methyldopa)
  6. Other antihypertensives (eg, guanethidine)
  7. QT-prolonging agents (eg, amiodarone, disopyramide, flecainide, procainamide, quinidine, sotalol)
  8. Other antidysrhythmics
  9. Psychoactive agents
  10. Anticonvulsants (eg, carbamazepine, phenytoin)
  11. Antiparkinsonian agents
  12. Central nervous system depressants (eg, barbiturates, benzodiazepines)
  13. Monoamine oxidase inhibitors
  14. Antidepressants
  15. Narcotic analgesics
  16. Sedating and nonsedating antihistamines
  17. Cholinesterase inhibitors (eg, donepezil, tacrine, galantamine)
  18. Drugs with other mechanisms
  19. Drugs of abuse (eg, cannabis, cocaine, alcohol, heroin)
  20. Digitalis
  21. Insulin and oral hypoglycemics
  22. Neuropathic agents (vincristine)
  23. Nonsteroidal antiinflammatory drugs
  24. Bromocriptine

3] What are the red flags on history and physical exam in syncope? 


  • Event: 
    • Preceded by chest pain/Headache/abdo pain 
    • Sudden onset with no warning/prodrome. Conversely, look for that vasovagal prodrome or inciting event (eg postmicturition) 
    • Exertional syncope 
    • GI bleeding 
    • Associated PV bleeding or cramping in female of childbearing age  
    • Dyspnea, hemoptysis 
    • Features that would suggest a mimic (eg postictal phase, tongue bite) 
    • Fevers, chills, other infectious symptoms 
  • PMHx/Meds: 
    • VTE risk factors 
    • Meds that can precipitate syncope (also look at recent changes – esp. Diuretics, beta blockers, antihypertensives) 


Vitals – pay close attention (HR too fast, slow, hypoxia, hypotension etc) 

Neuro – LOC, lateralizing deficits

Cardiac/Resp – murmurs, pulses (unequal in dissection, subclavian steal), volume status

Abdominal/Rectal/GU (if concern for bleeding, tenderness etc) 

[4] What are 5 ECG findings to look for in the syncopal patient?

  1. Dysrhythmias
  2. Pre-excitation
  3. Shortened PR
  4. Prolonged QTc
  5. ST Elevation (regional and diffuse)
  6. Brugada pattern (RBBB in association with ST elevation in V1-V3)
  7. Right ventricular strain pattern
  8. Electrical alternans

[5] What are markers of increased short-term risk in syncope patients?  See Box 12.4

The following list is adapted from Box 12.4 in Rosen’s 9th Edition.

  1. Age >65 years
  2. Male gender
  3. History of CHF
  4. History of CVD or serious dysrhythmia
  5. History of structural heart disease
  6. Family history of early (<50 years) sudden death
  7. Syncope without prodrome
  8. Exertional syncope
  9. Dyspnea or shortness of breath
  10. Syncope during supine position
  11. Hypotension – systolic BP <90 mmHg
  12. Abnormal EKG
  13. Anemia with HCT <30% or hemoglobin <90 g/L

[6] List five indications for admission and inpatient evaluation for the patient with syncope?

According to Rosen’s 9th Edition, the following are indications for admission and inpatient evaluation of patients with syncope:

  1. Presence of chest pain
  2. Dyspnea or SOB that is unexplained
  3. History of CHF
  4. History of significant valvular disease
  5. Patients with electrocardiographic evidence of ventricular dysrhythmias,ischemia, significant QT prolongation, or new bundle branch block

Potentially consider prolonged monitoring for patients with:

  1. Age > 65 years
  2. Pre-existing cardiovascular or congenital heart disease
  3. Family history of sudden death
  4. Serious comorbidities (e.g., diabetes mellitus)
  5. Exertional syncope


[1] What is the significance of a patient presenting with syncope vs. near syncope? 

This is a question we have all asked ourselves at one time or another. We so often have patients who complain about a vague history of lightheadedness on review of systems, and for many emergency clinicians, complaints of presyncope are often seen as being less worrisome. However, some new research suggests that presyncope is JUST AS SIGNIFICANT as complaints of syncope.

Study: Bastani A et al. Comparison of 30-Day Serious Adverse Clinical Events for Elderly Patients Presenting to the Emergency Department with Near-Syncope Versus Syncope. Ann Emerg Med 2018. PMID: 30529112

Design: Prospective observational study


  • Primary Outcome
    •  Incidence of 30-day death or serious clinical events


  • Syncope Group
    • 18.2% mortality or serious clinical events
  • Presyncope Group
    • 18.7% mortality or serious clinical events

Clinical Predictors of Serious Outcomes

  • Dyspnea
  • Abnormal EKG
  • History of Dysrhythmia
  • Physician Risk Assessment (i.e., gestalt)

For more nuanced FOAMed evaluation of this article, check out REBEL EM’s post here:

[2] What is the utility of orthostatic vital signs? 

We all know that orthostatic vitals to assess a patient’s fluid status are not necessarily useful. However, according to Rosen’s 9th Edition, orthostatic vitals could add valuable evidence to your diagnostic work up.

New evidence, however, suggests this is not the case. In a critical appraisal by Schaffer et al. published in the Journal of Emergency Medicine in 2018 ( show that orthostatic changes in the emergency department do not reliably diagnose or exclude orthostatic syncope. Additionally, orthostatic vitals do not help to exclude the existence of a potentially serious or life threatening cause of a patient’s syncope.  

[3] What degree of cerebral hypoperfusion is needed to cause unconsciousness?  

Quick little tidbit to help you impress your attending on your next ED shift:

  • Hypoperfusion resulting in a reduction of cerebral blood flow by >/35% will reliably results in unconsciousness
  • This hypoperfusion can be the result of changes in CO, SVR, blood volume, regional systemic vascular resistance

Dillan Radomske

Dillan Radomske is an Emergency Medicine resident at the University of Saskatchewan. He is passionate about technology-enhanced medical education, podcast creation and production, and Indigenous advocacy. He is one of the new CRACKCast hosts, and aspires to continue to contribute to the field of FOAMed in the future.

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Owen Scheirer

Owen is a resident in the FRCPC Emergency Medicine program at the University of Saskatchewan. When he's not running around the emergency department, he's hanging out with his wife, new baby girl, and dog. Spare time = climbing and cycling!

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Chloe LaBrie

Dr. Chloe LaBrie is a UBC Family Medicine resident in Nanaimo, British Columbia. She is interested in EM and has recently been accepted into the FM-EM Program at the University of Alberta in Edmonton. She is interested in Indigenous Health and the dissemination of high-quality Emergency Medicine content via FOAMed.

Latest posts by Chloe LaBrie (see all)