Initial Workup for Syncope
The initial workup for syncope should include a thorough history, physical examination with orthostatic vital signs, and a 12-lead ECG, as these are the most effective tools for determining the cause and risk stratification of syncope. 1, 2
Step 1: History and Physical Examination
Key Historical Features to Assess:
- Cardiac vs. Non-Cardiac Features:
- Cardiac red flags: Age >60 years, male sex, known heart disease, brief/absent prodrome, syncope during exertion, syncope in supine position, low number of episodes (1-2), family history of sudden cardiac death 1, 2
- Non-cardiac features: Younger age, no known cardiac disease, standing position only, clear positional trigger, typical prodrome (nausea, warmth), specific triggers (cough, laugh, micturition) 1, 2
Physical Examination Components:
- Orthostatic vital signs (lying, sitting, immediate standing, and after 3 minutes) 1
- Cardiac examination (murmurs, gallops, rubs) 1
- Basic neurological examination 1
Step 2: 12-Lead ECG (Class I, B-NR)
A 12-lead ECG is essential for all patients with syncope to identify:
- Bradyarrhythmias or conduction disorders
- Ventricular tachyarrhythmias
- Pre-excitation patterns (Wolff-Parkinson-White)
- Channelopathies (Brugada, Long QT)
- Structural heart disease markers (LV hypertrophy, ARVC) 1, 3
Step 3: Risk Stratification and Disposition
Based on initial evaluation, determine:
High-Risk Features (Hospital Admission Recommended):
- Serious medical condition identified during initial evaluation 1
- Suspected cardiac syncope with abnormal ECG or cardiac history 1, 2
- Syncope during exertion 1, 2
- Syncope without warning/prodrome 2
- Family history of sudden cardiac death 2
Low-Risk Features (Outpatient Management):
- Presumptive reflex-mediated syncope 1
- Age <45 years, no cardiovascular disease, normal ECG 2
- Clear positional trigger or situational context 2
- Typical prodrome present 2
Intermediate-Risk:
- Consider structured emergency department observation protocol 1
Step 4: Targeted Additional Testing
Laboratory Testing:
- Targeted blood tests based on clinical assessment (Class IIa, B-NR) 1
- Avoid routine comprehensive laboratory testing (Class III: No Benefit, B-NR) 1
- Brain natriuretic peptide and high-sensitivity troponin may be considered if cardiac cause suspected (Class IIb, C-LD) 1
Cardiac Imaging:
- Echocardiography if structural heart disease suspected (Class IIa, B-NR) 1, 2
- Avoid routine cardiac imaging if no cardiac etiology suspected (Class III: No Benefit, B-NR) 1
Cardiac Monitoring:
Select based on frequency and nature of syncope events:
- Holter monitor: For frequent symptoms likely to occur within 24-72 hours 1, 2
- External loop recorder/patch recorder/mobile cardiac outpatient telemetry: For less frequent episodes 1, 2
- Implantable cardiac monitor: For selected patients with suspected arrhythmic etiology (Class IIa, B-R) 1
Additional Testing:
- Exercise stress testing: If syncope occurs during exertion (Class IIa, C-LD) 1, 2
- Tilt-table testing: For suspected vasovagal syncope or delayed orthostatic hypotension 2
Common Pitfalls to Avoid
- Overuse of neuroimaging: MRI/CT of head is not routinely recommended without specific neurological indications 2
- Unnecessary EEG: Not routinely indicated without specific neurological symptoms 2
- Overlooking orthostatic hypotension: Always perform orthostatic vital signs 1
- Missing cardiac syncope: Higher mortality (18-33% at 1 year) compared to non-cardiac causes (3-4%) 2
- Age-specific considerations: Older adults more likely to have orthostatic, carotid sinus hypersensitivity, or cardiac syncope; younger adults more commonly have vasovagal syncope 2
Remember that the history is the most powerful diagnostic tool in syncope evaluation, with the physical examination and ECG completing the initial assessment triad that will establish the diagnosis in most patients 4, 5.