Syncope

For pediatric patients patients see syncope (peds)

Background

  • 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
  • No preceding symptoms
    • Concerning for cardiac dysrhythmia
  • 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, shortness of breath or palpitations
  • Use of medications that can alter cardiac conduction

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 [1]
    • Associated with head movement or pressure on neck
  • Orthostatic hypotension-mediated syncope
    • After standing up
    • Change in medications

Differential Diagnosis

Syncope Causes

Evaluation

Work-Up

ACEP only recommends ECG and H&P as must haves

  • ECG
    • Perform on every patient, unless trigger clearly identified (i.e. following blood draw) and no risk factors
  • Urine pregnancy


Consider based on history/symptoms
  • CBC (or POC hemoglobin) & chemistry (or POC glucose)
  • Troponin
    • Not recommended to rule out AMI in patients with isolated syncope[2]
    • Elevated troponin predicts adverse cardiac outcome in syncope[3]
    • May be useful for risk stratification
  • CXR
  • Orthostatics (symptomatic)
  • Guaiac
  • 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[4] showed that 7.14% of patients admitted for syncope had a pulmonary embolism and of the cohort that were not low risk with a negative d-dimer, the risk was as high as 17.3%
    • 2018 systematic reviewed [5] showed 0.8% of admitted ED pts with syncope had PE
    • Also supported by 2019 study showing prevalence of 2.3% in undifferentiated patients admitted with syncope[6].
    • Both of these two studies refute the findings of the PESIT study listed first
  • Bedside US
    • PSL view may show thickened ventricular septum
    • High sensitivity to rule out AAA

Diagnosis

Management

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

Disposition

Admit[11]

  • 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
  • Exertional syncope in younger patients without an obvious benign cause

Discharge

  • None of the above findings (esp if age <45)
  • No events on telemetry after period of observation (2-4 hours in the ED)
  • Consider referral for holter or til-table test
  • Instruct to avoid precipitating factors, such as extreme heat, dehydration, postexertional standing, alcohol and certain medications

Additional Risk Stratification Tools for Selecting Low-Risk patients for Discharge

Canadian Syncope Risk Score[12] MDCalc

Category 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 and only 0.3% 30 day adverse events for very low risk patients in 2020 Jama study [13]

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
Criteria (CHESS Pneumonic)[14]

Limitations

  • Performed poorly on external validation[15]
  • External validation of San Francisco Syncope Rule showed sensitivity 90% but only specificity of 33% [16]

Calculators

San Francisco Syncope Rule

San Francisco Syncope Rule (CHESS)
Criteria (CHESS) No Yes
C — History of CHF 1
H — Hematocrit <30% 1
E — Abnormal ECG (new changes or non-sinus rhythm) 1
S — Shortness of breath 1
S — Systolic BP <90 mmHg at triage 1
Risk Factors / 5
Interpretation
0 Low risk — 2% risk of serious outcome at 30 days. Consider discharge with outpatient follow-up.
≥1 Not low risk — Cannot be classified as low risk. Consider further workup or admission.
References
  • Quinn JV, Stiell IG, McDermott DA, et al. Derivation of the San Francisco Syncope Rule. Ann Emerg Med. 2004;43(2):224-232. PMID 14747812.
  • Quinn JV, Stiell IG, McDermott DA, et al. The San Francisco Syncope Rule vs physician judgment and decision making. Am J Emerg Med. 2005;23:782-786.
  • Note: Sensitivity ~98% for serious outcomes. Some validation studies show lower performance. Use with clinical judgment.

External Links

See Also

References

  1. ↑ 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
  2. ↑ 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
  3. ↑ Reed MJ, Mills NL, Weir CJ. Sensitive troponin assay predicts outcome in syncope. Emerg Med J. 2012;29(12):1001- 1003
  4. ↑ 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.
  5. ↑ 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
  6. ↑ Prevalence of pulmonary embolism in patients with syncope Badertscher P, du Fay de Lavallaz J, Hammerer-Lercher A, et al. J Am Coll Cardiol. 2019;74(6):744-754.
  7. ↑ 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
  8. ↑ Quinn J, McDermott D. Electrocardiogram findings in emergency department patients with syncope. Acad Emerg Med. 2011;18(7):714-718
  9. ↑ 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
  10. ↑ 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
  11. ↑ 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
  12. ↑ 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.
  13. ↑ Multicenter Emergency Department Validation of the Canadian Syncope Risk Score. JAMA Intern Med. 2020 Mar 23. https://doi.org/10.1001/jamainternmed.2020.0288
  14. ↑ 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.
  15. ↑ 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.
  16. ↑ Thiruganasambandamoorthy et al, External validation of the San Francisco Syncope Rule in the Canadian setting. Ann Emerg Med. 2010 May;55(5):464-72. doi: 10.1016
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