Why it matters
Syncope is a bread-and-butter ED complaint, but it hides killers among the benign. Most faints are vasovagal, but a subset are due to malignant arrhythmias. Missing them can be fatal. Every rookie must separate the “I stood up too fast” from “I dropped dead at my desk.”
1) The 30-second story
- Vasovagal/benign syncope → prodrome (lightheaded, diaphoresis, nausea), clear trigger, quick recovery.
- Arrhythmic syncope → sudden, without warning, often during exertion or at rest, rapid recovery but high risk of recurrence/death.
- At work collapse in an otherwise healthy patient? Always rule out arrhythmia first.
2) Quick differential
- Cardiac causes: ventricular tachycardia, long QT torsades, AV block, WPW, Brugada, hypertrophic cardiomyopathy.
- Neurogenic: seizure, TIA, stroke (rare isolated syncope).
- Vasovagal/orthostatic: pain, stress, dehydration, antihypertensives.
- Other: PE, hypoglycemia, severe anemia, GI bleed.
3) Red flags 🚨
- Syncope during exertion or at rest with no prodrome.
- Family history of sudden cardiac death.
- Palpitations before syncope.
- Abnormal ECG (QT prolongation, delta wave, Brugada, heart block, ischemic changes).
- Structural heart disease (HCM, valvular disease, CHF, prior MI).
- Syncope causing injury (head strike, prolonged LOC).
- Elderly with multiple comorbidities.
4) Bedside exam & first steps
- Vitals: orthostatics may help but don’t delay higher-risk workup.
- Neuro exam: usually normal in syncope; abnormal exam pushes to neuro causes.
- Cardiac exam: murmurs (HCM, AS), irregular pulse (AFib, tachyarrhythmias).
- Glucose: quick check for hypoglycemia.
- POCUS: look at EF, valvular disease, RV strain (PE suspicion).
5) Investigations
- ECG: cornerstone. Look for:
- Wide complex tachycardia, AV block
- Brugada pattern
- WPW (short PR, delta wave)
- Prolonged QT
- Ischemic ST changes
- Labs: CBC (anemia), BMP/Mg (electrolytes), troponin if ACS suspicion.
- CXR: if CHF, PE suspicion.
- Telemetry/monitoring: continuous while in ED.
- Further tests: Echo, Holter, tilt-table, EP studies (outpatient).
6) Management in the ED
- Unstable arrhythmia → ACLS: defibrillate VT/VF, pace high-grade AV block, give Mg for torsades.
- Stable but suspicious ECG → admit/cardiology consult.
- Benign vasovagal → fluids, reassurance, discharge if no red flags and normal ECG.
- PE suspicion → CT angio, anticoagulation as indicated.
- Young with family history of sudden death → cardiology follow-up even if ECG normal.
7) Disposition
- Admit/observe:
- Any abnormal ECG
- Unexplained syncope in heart disease patient
- Syncope during exertion
- Syncope with family history of sudden cardiac death
- Discharge safe:
- Typical vasovagal syncope with prodrome, normal ECG, no heart disease, stable vitals, reliable follow-up.
Rookie pearls
- ECG is king in syncope — never skip it.
- “No prodrome + sudden collapse” = arrhythmia until proven otherwise.
- Ask about family history — sudden unexplained deaths can reveal HCM, long QT, Brugada.
- Don’t call a seizure without evidence — true seizures have postictal period, tongue bite, incontinence.
- Admit if you’re uneasy — better safe than a sudden death at home.
Common pitfalls
- Discharging “just another faint” without ECG.
- Overcalling seizure and missing arrhythmia.
- Ignoring electrolyte disturbances (hypoK, hypoMg).
- Assuming young age = benign; many lethal arrhythmias strike the young.
- Forgetting PE, HCM, aortic stenosis in syncope differential.
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