• Syncope is the transient loss of postural tone and consciousness from cerebral hypoperfusion
  • Syncope and pre-syncope are worked up the same
  • Important questions to consider during evaluation:
    • 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?

Risk Factors for Serious Cause

  • Exertion preceding the event
  • History of cardiac disease in the patient
  • Family history of sudden death, deafness, or cardiac disease
  • Recurrent episodes
  • Recumbent episode
  • Prolonged loss of consciousness
  • Associated chest pain or palpitations
  • Use of medications that can alter cardiac conduction

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
  • NOT validated by external studies[1]
Criteria (CHESS Pneumonic)[2]

Clinical Features

Physical Exam

  • Evaluate volume status
  • Evaluate for head and neck trauma (related to fall from syncopal event)
  • Focus cardiac exam on detecting murmurs (aortic stenosis, mitral regurgitation, tricuspid stenosis)
  • Evaluate for signs of heart failure
  • Palpate abdomen for pulsating mass (AAA)
  • Rectal exam to eval for GI bleed
  • Thorough neurologic exam
  • Examine for possible sources of infection

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 [3]
    • 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[4]


  • ACEP only recommends ECG and H&P as must haves
  • ECG
    • Normal ECG has high NPV[5]
    • Perform on every patient, unless trigger clearly identified (i.e. following blood draw) and no risk factors
    • Rule out: ischemia, heart block, WPW, long QT, short QT, Brugada, HOCM, ARVD, early repolarization, low voltage/pericardial effusion, RV strain pattern
    • ECG findings associated with adverse cardiac outcome in 30 days: [6][7]
      • LBBB, 2nd degree Mobitz II, 3rd degree AV block, RBBB w/LAFP or LPFB
  • Urine pregnancy
Consider based on history/symptoms
  • CXR
    • Obtain if symptomatic (i.e. to rule out dissection)
  • Hemoglobin
  • Chemistry
  • Orthostatics (symptomatic)
  • Troponin
    • Not recommended to rule out AMI in patients with isolated syncope[8]
    • Elevated troponin predicts adverse cardiac outcome in syncope[9]
    • May be useful for risk stratification
  • Guaiac
  • Bedside US
    • PSL view may show thickened ventricular septum
    • High sensitivity to rule out AAA
  • CT scan of head is not recommended in asymptomatic, insignificant trauma with normal neurologic examination


  • Treat underlying cause, if known



  • 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)


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

External Links



See Also


  1. 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.
  2. 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.
  3. 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
  4. 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
  5. 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
  6. Quinn J, McDermott D. Electrocardiogram findings in emergency department patients with syncope. Acad Emerg Med. 2011;18(7):714-718
  7. 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
  8. 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
  9. Reed MJ, Mills NL, Weir CJ. Sensitive troponin assay predicts outcome in syncope. Emerg Med J. 2012;29(12):1001- 1003
  10. 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