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

Initial Workup for Syncope

The initial evaluation of a patient presenting with syncope must include a careful history, physical examination including orthostatic blood pressure measurements, and standard electrocardiogram (ECG). 1

Step 1: Confirm True Syncope

First, determine if the event was truly syncope by confirming:

• Complete loss of consciousness
• Transient episode with rapid onset and short duration
• Spontaneous, complete recovery without sequelae
• Loss of postural tone

If any of these features is absent, consider non-syncopal causes of transient loss of consciousness before proceeding with syncope evaluation 1.

Step 2: Detailed History Collection

Obtain specific information about:

Circumstances before the attack:

• Position (supine, sitting, standing)
• Activity (rest, posture change, during/after exercise, during/after urination/defecation)
• Predisposing factors (crowded places, prolonged standing, post-prandial period)
• Precipitating events (fear, pain, neck movements)

Onset of the attack:

• Presence of prodromal symptoms (nausea, sweating, feeling cold, blurred vision)
• Palpitations (suggesting arrhythmic cause)

During the attack (from witnesses):

• Way of falling
• Skin color changes
• Duration of unconsciousness
• Breathing pattern
• Movements (tonic, clonic, minimal myoclonus)

End of the attack:

• Post-recovery symptoms (nausea, confusion, muscle aches)
• Injuries sustained
• Chest pain or palpitations
• Urinary or fecal incontinence

Background information:

• Family history of sudden death or cardiac disease
• Previous cardiac disease
• Neurological conditions
• Metabolic disorders (diabetes)
• Current medications 1

Step 3: Physical Examination

• Complete cardiovascular examination
• Orthostatic blood pressure measurements (essential component)
• Neurological examination if non-syncopal causes suspected

Step 4: 12-lead ECG

ECG is critical as it can identify:

• Bradycardia
• Atrioventricular block
• Intraventricular conduction abnormalities
• Tachydysrhythmias
• ST-segment/T-wave abnormalities suggesting acute coronary syndrome
• Ventricular preexcitation (Wolff-Parkinson-White)
• Brugada syndrome patterns
• Prolonged QT interval
• Right ventricular hypertrophy suggesting hypertrophic cardiomyopathy 2

The ECG is particularly important as it has 100% negative predictive value for AMI when normal in syncope patients 3.

Step 5: Risk Stratification

After initial evaluation, assess risk using validated scores:

• San Francisco Syncope Rule
• OESIL score
• EGSYS score

High-risk features include:

• Abnormal ECG
• History of cardiovascular disease
• Age >65 years
• Lack of prodrome
• Syncope during effort or while supine
• Palpitations before syncope 1

Step 6: Additional Testing Based on Initial Findings

Based on initial evaluation, perform:

1. If cardiac disease suspected or abnormal ECG:

   • Echocardiogram
   • Holter monitoring or immediate ECG monitoring
   • Exercise testing 1, 4

2. If reflex syncope suspected:

   • Carotid sinus massage (in patients >40 years)
   • Tilt table testing 1

3. If orthostatic syncope suspected:

   • Lying-to-standing orthostatic test
   • Head-up tilt testing 1

4. If non-syncopal causes suspected:

   • Neurological evaluation
   • Blood tests 1

Important Caveats and Pitfalls

1. ECG interpretation is crucial - The ECG is one of the most important diagnostic tools in syncope evaluation. Patients with a normal ECG are unlikely to have structural cardiac abnormalities (0% in one study) 5.

2. Don't miss cardiac syncope - Patients with coronary artery disease and reduced ejection fraction (≤25%) remain at risk for sudden death and ventricular arrhythmias (up to 10%/year) even with a negative electrophysiologic study 6.

3. Bundle branch blocks require attention - The presence of bundle branch block at initial evaluation predicts the occurrence of bradycardia at follow-up 6.

4. Troponin testing has limited utility - Troponin estimation provides little additional benefit beyond the presenting ECG in identifying syncope due to AMI. A normal ECG effectively rules out AMI in patients with isolated syncope 3.

5. Avoid unnecessary testing - Structural cardiac evaluation may not be required in patients with a normal ECG in an observation setting 5.