Syncope risk stratification, differential and disposition from the ED.

1. Syncope
Dr Andrew Crofton
Disclaimer: https://criticalcarecollaborative.com/disclaimer/

2. Introduction
• 1-2% of ED visits
• 6% of hospital admissions
• Near-syncope shares the same pathophysiological processes and
may carry the same risks
• Syncope in the preceding year is the best predictor of recurrence
• Annual incidence
• 2% if over 80yo
• 1.1% if 70-79
• 0.5% if <70yo

3. Pathophysiology
• Common pathway is about 10 seconds of complete disruption of blood
flow or nutrient delivery to both cerebral cortices or the reticular
activating system, or reduction in cerebral perfusion by 35-50%
• Even with exhaustive investigation the cause remains unknown in around
40% (60% after ED-only investigations)
• Risk of death
• Cardiac syncope 2x
• Neurologic syncope 1.5x
• Syncope of unknown cause 1.3x
• Vasovagal syncope carries no increased risk of death

4. Causes
• Vasovagal 21%
• Cardiac 10%
• Orthostatic 9%
• Medications 7%
• Neurological 4%
• Psychiatric (50% of cases in young adults)
• Unknown 37%

5. Cardiac syncope
• Most dangerous with 6 month mortality >10%
• Structural
• Valvular heart disease (AS/TS/MS)
• Cardiomyopathy
• Pulmonary HTN
• Congenital heart disease
• Myxoma
• Pericardial disease
• Aortic dissection
• PE
• Myocardial ischaemia
• MI
• Dysrhythmic
• Brady – Short or long QT, Stokes-Adams, Sinus node disease, second or third-degree HB, pacemaker
malfunction
• Tachy – VT, torsades, SVT, Afib/flutter

6. Cardiac syncope
• Always consider AS in the elderly
• Classic chest pain, dyspnoea on exertion and syncope
• Dysrhythmic syncope is typically sudden and without prodromal
symptoms

7. Vasovagal syncope
• Form of reflex-mediated syncope associated with inappropriate
vasodilatation, bradycardia or both as a result of inappropriate
vagal or sympathetic tone
• Prodrome of lightheadedness +- nausea, pallor, sweating and
feeling of warmth may accompany syncope
• Slow, progressive onset with associated prodrome is suggestive of
vasovagal syncope
• Situational syncope occurs after coughing, micturition, defecation
or swallowing

8. Carotid sinus hypersensitivity
• Another type of reflex-mediated syncope
• Bradycardia and/or hypotension
• External pressure on abnormally sensitive carotid body results in:
• Abnormal vagal response (bradycardia and asystole of >3 seconds) AND/OR
• Vasodepressor response (decrease in BP >50mmHg without bradycardia)
• Both responses may occur simultaneously
• More common in men, elderly and in those with ischaemic heart disease, HTN
and certain head and neck malignancies
• Consider in older patients with recurrent syncope and negative cardiac
evaluations
• Can only be definitively diagnosed if clinical hypersensitivity is reproducible and
event was associated with an inciting event e.g. shaving/turning head

9. Orthostatic syncope
• Postural hypotension with syncope or presyncope
• Symptom onset is usually within 3 minutes of upright position, but
can be delayed in some patients
• Positive orthostatic changes are seen in 40% of asymptomatic
patients >70yo and 25% of those under 60 so orthostasis does not
always result in syncope
• Causes include intravascular volume loss, poor vascular tone or
medications
• Always consider other life-threatening causes, especially in the
elderly, as they too may be contributing to orthostatic changes

10. Psychiatric disorders
• Found in 40% of those with vasovagal syncope and 62% of those
with unexplained syncope
• Generalised anxiety and major depression most commonly
• Hyperventilation can lead to syncope through hypocarbia and
cerebral vasoconstriction
• Patients tend to be younger, with repeated episodes of syncope
and multiple prodromal symptoms
• Diagnosis of exclusion

11. Neurologic syncope
• Symptoms must be transient with no persistent neurological deficits to meet definition of syncope
• Brainstem ischaemia, vertebrobasilar atherosclerotic disease and basilar artery migraine may all cause
transient decreases in blood flow to the RAS leading to sudden, brief episodes of LOC
• Typically LOC is preceded by blurred vision, vertigo, focal neurological deficits or nausea
• Subclavian steal syndrome
• A rare cause of brainstem ischaemia due to abnormal narrowing of subclavian artery proximal to origin of vertebral
artery so that with exercise of the ipsilateral arm, blood is shunted from the vertebrobasilar artery to the subclavian
artery to the arm
• More common on the left and may have reduced pulse volume and BP on affected side
• Subarachnoid haemorrhage
• Usually has associated focal neurological deficits, headache or persistent ALOC
• Can get transient rise in ICP with concomitant reduced CPP and thus get true syncope in rare cases
• Seizure
• Most commonly confused diagnosis but a clear history should delineate from other causes of syncope
• Prodromal aura, post-ictal confusion and muscle ache suggests seizure
• Prodromal vasovagal symptoms suggest vasovagal
• Urinary incontinence is not helpful
• Witnessed head turning, shaking or unusual posturing suggests seizure

12. Medication syncope
• Most common means of syncope is orthostasis (especially in elderly)
• Erectile dysfunction drugs
• Antihypertensives
• Beta-blockers and CCB
• Digoxin
• Diuretics
• Proarrhythmic agents may cause dysrhythmias
• Antipsychotics
• Antiparkinsonism drugs
• Antidepressants
• Phenothiazines
• Nitrates
• Alcohol
• Cocaine

13. Key history
• Chest pain – MI, AS, dissection, PE
• Palpitations – Arrhythmia
• SOB - PE, CCF, AS
• Headache – SAH
• Abdominal or back pain – Ruptured AAA, perforated viscous or ectopic pregnancy
• No prodrome and events associated with exertion – Cardiac, AS, HOCM
• Turning head, shaving or neck compression – Carotid sinus hypersensitivity
• Onset with single limb exercise – Subclavian steal syndrome
• Previous episodes
• >5 episodes per year = more likely vasovagal or psychiatric than dysrhythmia
• Medications and drugs
• FHx – Brugada, short/long QT, arrythmogenic RV dysplasia, sudden cardiac death, HOCM
• Special attention to single-car MVA (frequently elderly driving off road) as focus is on trauma when cause may be syncopal

14. Examination
• Assess for trauma – If no evidence of protecting themselves, consider
sudden LOC i.e. cardiac (but can be seen in both)
• Bilateral BP – Subclavian steal, dissection
• Orthostatic BP after 5 min in supine position measured at 1 and 3
minutes after standing
• Symptomatic drop of >20mmHg is significant as is any drop below 90
independent of symptoms
• Heart sounds
• Focal neurological
• PR testing for GI bleeding

15. ECG
• Prolonged QTc >470ms (>500ms associated with significant outcomes)
• Short QTc <350ms
• New or old LBBB, LAFB or LPFB or QRS widening are 3.5x more likely to
be associated with morbidity
• Non-sinus rhythms are 2.5x more likely to be associated with morbidity
• Labs as indicated
• Identifies diagnosis in 5% of syncope
• Abnormal ECG in patient without obvious cause of syncope has OR of 8
for serious cardiac arrhythmia

16. ECG
• Ischaemia
• Arrhythmia
• Major conduction defect
• HOCM
• Ventricular pre-excitation
• Prolonged/short QTc
• LV strain due to aortic disease
• Brugada
• RV dysplasia

17. Carotid massage
• Potentially indicated in patients with symptoms suggestive of carotid sinus
syndrome
• Can massage each carotid body for 5-10 sec
• Positive if symptoms reproduced in presence of asystole >3 seconds or decrease
in SBP >50mmHg
• Do not perform if known carotid stenosis, bruits presents or <3mo hx of stroke
or MI or hx of VT or VF
• Needs informed consent
• Deficits lasting >24 hours occur in 0.1% of patients
• Most patients with positive test do NOT have true carotid sinus syndrome so
given low risk but potentially catastrophic complications, usually not performed

18. Hyperventilation manoeuvre
• Open-mouthed, slow, deep breaths at 20-30/min for 2-3 min with
recurrence of prodromal symptoms or syncope significantly
correlates with psychiatric causes of syncope

19. High risk features for ‘cardiac’ syncope
• Onset – No prodromal symptoms or while sitting
• >55yo (OR 5.4)
• Hx of CCF (OR 3-5) or CAD
• Ventricular ectopy
• Abnormal ECG
• FHx of SCD
• Significant trauma from syncopal episode

20. Canadian Arrhythmia syncope risk score
• Predisposition to vasovagal - -1 points
• Hx of heart disease – 1
• SBP <90 or >180 – 1
• Raised Tn – 2
• QRS axis <-30 or >100 – 1
• QRS >130ms – 1
• QTc >480ms -1
• ED diagnosis of vasovagal - -2 points
• ED diagnosis of cardiac syncope – 2 points

21. Canadian Arrhythmia syncope risk score
• Score and risk of serious outcome in 30 days (%)
• -3: 0.4
• -2: 0.7
• -1: 1.2
• 0: 2
• 1: 3
• 2: 5
• 3: 8
• 4: 13
• 5: 20
• 6: 29
• 7: 40
• 8: 53
• 9: 65
• 10: 76
• 11: 84

22. Unexplained syncope
• Martin et al. risk factors for arrhythmias or death at 1 year
• Hx of arrhythmia
• Hx of CCF
• Abnormal ECG
• Age >45
• San Francisco syncope rule (Quinn et al.)
• Adverse outcomes at 7 and 30 days with 89% sensitivity and 52% specificity for death at 1 year if 1 of below high risk
features:
• Hx of CCF
• Abnormal ECG (any new change or non-sinus rhythm - if never seen before, any abnormality at all)
• Hct <30
• SOB
• SBP <90 in the ED
• Any 1 of above = 12% risk of serious outcome at <7 days (sens 85-95%; speci 50-60%)
• Note:
• Isolated PAC, 1st degree AV block likely non-significant across other studies
• Isolated RBBB, isolated LAFB, frequent PAC’s and the odd PVC are also less worrisome but not entirely okay

23. Unexplained syncope
• OESIL score
• Age >65
• Hx of CVD (IHD, CCF, Cerebrovascular or PVD)
• Abnormal ECG (ischaemia, arrhythmias, prolonged QT, AV block or BBB)
• Absence of typical prodrome
• Other risk factors that may warrant admission include:
• FHx of sudden cardiac death
• Syncope while supine
• Syncope during exercise
• Syncope without prodromal symptoms
• Palpitations preceding syncope
• Age >60 or >65 (no specific age cut-off but <45 is clearly low risk if no other
factors present)

24. Risk stratification (Cameron)
High risk Low risk
Chest pain consistent with IHD Age <45
Hx of CCF Otherwise healthy
Hx of ventricular dsyrhythmia Normal ECG
Pacemaker, defib dysfunction Normal CV exam
Age >60 Prodrome consistent with vasovagal
Abnormal ECG
Those considered high-risk need continuous cardiac monitoring for at least 24 hours and admission
+- Echo for structural heart problems

25. Disposition
• Admission for monitoring is under question as to its utility
• Echo should be performed in those with known or suspected
structural heart disease
• Usually abnormalities are clinically apparent and will seldom be found in
those with normal cardiac exam and ECG
• Stress testing may be used to identify exercise-induced
dysrhythmias or ischaemia or reproduce exertional syncope once
HOCM is ruled out
• EP studies reserved for documented dysrhythmias, preexcitation
or underlying cardiac disease

26. Disposition
• Admission criteria
• Organic cause found
• Monitored bed if:
• Suspected cardiac arrhythmia
• >1 unexplained syncopal episode in last 48 hours
• Short stay if unsupervised social situation

27. Outpatient investigation
• Implantable loop recorders
• >50% yield for recurrent syncope
• Tilt table testing
• Recommended for recurrent, unexplained syncope
• Identifies reflex-mediated syncope
• Psychiatric referral
• For young patients without underlying heart disease who have frequent syncopal events
• Prolonged QT
• Referral for genetic testing for LQTS gene
• If gene negative, patients at very low risk of fatal syncope
• EEG
• If suspected seizure

28. Prognosis
• No excess of mortality if no underlying heart disease
• Highest mortality in those with CCF
• 1/3 of those with syncope and structural heart disease will die
within 12 months
• Mortality rate at 12 months is 25% if cardiac cause vs. 6% if
uncertain cause

29. The elderly
• There is a gradual continuum of increased risk with increasing age
• Cardiovascular risk factors are better predictors of poor outcome than age itself
• Incidence of vasovagal syncope actually decreases with age due to decreased responsiveness of the
autonomic nervous systems
• Less sensitive thirst mechanism and decreased endocrine response to hypovolaemia, exacerbating
orthostatic hypotension
• Postprandial hypotension is more common in the elderly (esp. nursing home residents) due to rapid rate of
delivery from stomach into small intestine
• Baseline hypertension, atherosclerosis and valvular disease also contribute to cerebral hypoperfusion
• Increased risk of cardiac disease, ischaemia, MI, AS
• Diabetes leads to autonomic dysfunction and peripheral neuropathy
• Medication use is far more common with increased risks of orthostasis and decreased autonomic
responsiveness to orthostatic stress

30. Pregnant women
• Gravid uterus may impair IVC return
• Incidence of cardiac dysrhythmias (especially PVC’s) increases
during normal pregnancy
• No positive correlation between presyncope or syncope and
cardiac dysrhythmia in pregnant women
• Consider ruptured ectopic and PE in all pregnant women

31. Syncope vs. seizure
• Syncope has tongue biting on tip if any
• Eyes deviate upwards in syncope vs to side in seizure
• Duration of unconsciousness in syncope <1 min vs. >2 minutes in
seizure
• Post-event confusion <5 min in syncope vs. >5 min in seizure
• Post-event pulse rate usually slow in syncope (unless tachycardia
is cause)