For pediatric patients patients see syncope (peds)


  • Transient loss of postural tone and consciousness due to cerebral hypoperfusion
  • Syncope and pre-syncope assessed similarly
  • Important considerations:
    • Is this true syncope or something else (eg, stroke, seizure, head injury)?
    • If this is true syncope, is there a clear life-threatening cause?
    • If this is true syncope and the cause is not clear, is the patient at high risk for serious outcome?

Risk Factors for Serious Cause

  • Exertion preceding the event
    • Note that syncope during exertion much more concerning than syncope after exertion
  • History of cardiac disease in the patient
  • Family history of sudden death, deafness, or cardiac disease
    • Consider unexplained deaths and deaths due to single vehicle accidents
  • Recurrent episodes
  • Recumbent episode
  • Prolonged loss of consciousness
  • Associated chest pain or palpitations
  • Use of medications that can alter cardiac conduction

Canadian Syncope Risk Score[1]

' No Yes
Predisposition to vasovagal symptoms (triggered by being in a warm crowded place, prolonged standing, fear, emotion, or pain) 0 -1
Heart disease history (CAD, afib, flutter, CHF, valvular disease) 0 1
SBP < 90 or > 180mmHg 0 2
Elevated troponin 0 2
Abnormal QRS axis 0 1
QRS > 130ms 0 1
Corrected QT interval >480ms 0 2
Vasovagal syncope (based on clinical impression 0 -2
Cardiac Syncope (based on clinical impression) 0 2
  • Score < 0 associated with < 2% risk of serious adverse event at 30 days.
  • Externally validated per data presented at SAEM 2018.

San Francisco Syncope Rule

  • 1.4% of patients who are rule-negative will have a 7-day serious outcome
  • 10% of patients meeting the below criteria will have a 7-day serious outcome
  • Performed poorly on external validation[2]
Criteria (CHESS Pneumonic)[3]

Clinical Features

Physical Exam

Clinical Features by Cause

  • Cardiovascular-mediated syncope
    • Usually occurs without warning (absence of prodrome)
    • History of structural heart disease
    • Family history of sudden cardiac death
    • Syncope during exertion
    • Chest pain or palpitations associated with syncope
    • Abnormal ECG
  • Neurally mediated syncope
    • Trigger event (fear/pain, prolonged standing, warm environment)
    • Prodrome of nausea/vomiting, tunnel vision, lightheadedness, diaphoresis, warmth [4]
    • Associated with head movement or pressure on neck
  • Orthostatic hypotension-mediated syncope
    • After standing up
    • Change in medications

Differential Diagnosis

Syncope Causes


  • Overall yield of testing is low
  • Cardiovascular findings and evidence of bleeding strongest predictors of adverse outcomes after syncope[5]


ACEP only recommends ECG and H&P as must haves

Consider based on history/symptoms
  • CXR
    • Obtain if symptomatic (i.e. to rule out dissection)
  • Hemoglobin
  • Chemistry
    • Capillary glucose assessment sufficient in many cases
  • Orthostatics (symptomatic)
  • Troponin
    • Not recommended to rule out AMI in patients with isolated syncope[9]
    • Elevated troponin predicts adverse cardiac outcome in syncope[10]
    • May be useful for risk stratification
  • Guaiac
  • Bedside US
    • PSL view may show thickened ventricular septum
    • High sensitivity to rule out AAA
  • b-HCG in female patients of reproductive age to rule out ectopic pregnancy rupture as cause of syncope
  • CT scan of head is not recommended in asymptomatic, insignificant trauma with normal neurologic examination
  • Does PE need to be worked up?
    • NEJM paper by Prandoni[11] showed 3.8% of admitted ED pts with syncope had PE
    • 2018 systematic reviewed [12] showed 0.8% of admitted ED pts with syncope had PE



  • Treat underlying cause, if known (~50% of patients do not have a firm diagnosis)



  • Abnormal ECG
  • CHF
  • Suspicion of structural heart disease
    • Ischemic, dysrhythmic, obstructive, valvular
  • HCT <30
  • Shortness of Breath
  • Hypotension(SBP <90)
  • Family history of sudden cardiac death
  • Advanced age
  • Evidence of hemorrhage (occult blood)
  • Syncope without prodrome


  • None of the above findings (esp if age <45)
  • Consider referral for holter or til-table test

External Links

See Also


  1. Thiruganasambandamoorthy, V et al. Development of the Canadian Syncope Risk Score to predict serious adverse events after emergency department assessment of syncope. CMAJ. 2016 Sep 6;188(12):E289-E298.
  2. Birnbaum A, Esses D, Bijur P, Wollowitz A, Gallagher EJ. Failure to validate the San Francisco Syncope Rule in an independent emergency department population. Ann Emerg Med. 2008;52(2):151-9.
  3. Quinn J, McDermott D, Stiell I, Kohn M, Wells G. Prospective validation of the San Francisco Syncope Rule to predict patients with serious outcomes. Ann Emerg Med. 2006 May;47(5):448-54. PubMed PMID: 16631985.
  4. Romme JJCM, van Dijk N, Boer KR, et al. Influence of age and gender on the occurrence and presentation of reflex syncope. Clin Auton Res. 2008;18(3):127-133
  5. D’Ascenzo F, Biondi-Zoccai G, Reed M, 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
  6. Sud S, Klein GJ, Skanes AC, et al. Predicting the cause of syncope from clinical history in patients undergoing prolonged monitoring. Heart Rhythm. 2009;6(2):238-243
  7. Quinn J, McDermott D. Electrocardiogram findings in emergency department patients with syncope. Acad Emerg Med. 2011;18(7):714-718
  8. Thiruganasambandamoorthy V, Hess EP, Turko E, et al. Defining abnormal electrocardiography in adult emergency department syncope patients: the Ottawa Electrocardiographic Criteria. CJEM. 2012;14(4):248-258
  9. Reed MJ, Newby DE, Coull AJ, et al. Diagnostic and prognostic utility of troponin estimation in patients presenting with syncope: a prospective cohort study. Emerg Med J. 2010; 27(4):272-276
  10. Reed MJ, Mills NL, Weir CJ. Sensitive troponin assay predicts outcome in syncope. Emerg Med J. 2012;29(12):1001- 1003
  11. Prandoni P, Lensing AW, Prins MH, Ciammaichella M, Perlati M, Mumoli N, Bucherini E, Visonà A, Bova C, Imberti D, Campostrini S, Barbar S; PESIT Investigators. Prevalence of Pulmonary Embolism among Patients Hospitalized for Syncope. N Engl J Med. 2016 Oct 20;375(16):1524-1531. PubMed PMID: 27797317.
  12. Prevalence Of Pulmonary Embolism In Patients Presenting With Syncope: A Systematic Review And Meta-Analysis Oqab, Z., et al, Am J Emerg Med 36(4):551, April 2018
  13. Huff JS, Decker WW, Quinn JV et al. Clinical policy: critical issues in the evaluation and management of adult patients presenting to the emergency department with syncope. Ann Emerg Med. 2007;49(4):431-444