What is the initial workup for a patient presenting with syncope?

Initial Workup for Syncope

The initial workup for syncope should include a detailed history, physical examination, and 12-lead ECG for all patients, with risk stratification to guide further testing and management decisions. 1, 2

Risk Stratification

Risk stratification is essential to determine the likelihood of cardiac syncope, which carries higher mortality (18-33% at 1 year) compared to non-cardiac causes (3-4%) 1.

High-Risk Features (Require Hospitalization):

• Abnormal ECG findings (bundle branch blocks, prolonged QT)
• History of heart failure or structural heart disease
• Family history of sudden cardiac death
• Syncope during exertion or while supine/sleeping
• Syncope preceded by chest pain or palpitations
• Syncope triggered by loud noise or extreme emotional stress
• Syncope without prodrome (warning signs)
• Age >45 years with structural heart disease 1

Low-Risk Features:

• Age <45 years with no structural heart disease
• Normal ECG
• Clear vasovagal trigger
• No family history of sudden cardiac death 1, 2

Initial Diagnostic Evaluation

1. Detailed History - Focus on:

   • Circumstances surrounding the event (position, activity, triggers)
   • Prodromal symptoms (lightheadedness, nausea, visual changes)
   • Duration of unconsciousness
   • Post-event symptoms
   • Witness accounts
   • Previous episodes 1, 3

2. Physical Examination:

   • Vital signs including orthostatic measurements
   • Cardiovascular examination (murmurs, irregular rhythm)
   • Neurological assessment
   • Carotid sinus massage (in selected patients >40 years without carotid disease) 1

3. 12-lead ECG - Class I recommendation (Level B-NR) 1, 4

   • Can identify arrhythmias or conduction abnormalities
   • May provide immediate diagnosis in approximately 7% of cases 4
   • Look for: prolonged QT, Brugada pattern, pre-excitation, bundle branch blocks, arrhythmias

Additional Testing Based on Risk Stratification

For High-Risk Patients:

• Continuous ECG monitoring (Class I, B-NR) for hospitalized patients 1
• Echocardiogram (Class IIa, B-NR) when structural heart disease is suspected 1
• Exercise stress testing (Class IIa, C-LD) when syncope occurs during exertion 1
• Electrophysiological study (Class IIa, B-NR) for selected patients with suspected arrhythmic etiology 1

For Selected Patients:

• Tilt-table testing (Class IIa, B-R) for suspected vasovagal syncope, delayed orthostatic hypotension, or to distinguish convulsive syncope from epilepsy 1
• Prolonged ECG monitoring (insertable loop recorder) for recurrent unexplained syncope 5

Tests to Avoid Without Specific Indications

The following tests have low diagnostic yield and should NOT be routinely ordered (Class III: No Benefit) 1:

• MRI/CT of head
• Carotid artery imaging
• Routine EEG
• Extensive laboratory testing 1, 2

Common Pitfalls to Avoid

1. Overreliance on neuroimaging - Head CT/MRI rarely identifies syncope causes without focal neurological findings
2. Underestimating history importance - History and physical examination identify 56-85% of syncope causes 6
3. Missing cardiac causes - Absence of heart disease excludes cardiac syncope in 97% of patients 3
4. Failing to correlate symptoms with arrhythmias - Symptomatic correlation with arrhythmias is found in only 4% of patients with Holter monitoring 6
5. Not considering age-specific causes - Younger patients have higher likelihood of neuromediated syncope, while older patients have higher likelihood of cardiac causes 1

Key Diagnostic Clues

• Cardiac syncope: Occurs during supine position or effort, associated with blurred vision or convulsions in patients with heart disease 3
• Neurally mediated syncope: Long history (>4 years between episodes), abdominal discomfort before loss of consciousness, nausea and diaphoresis during recovery 3
• Palpitations: Only significant predictor of cardiac syncope in patients without heart disease 3