Syncope Workup
The appropriate workup for syncope should begin with a detailed history, physical examination with orthostatic blood pressure measurements, and a 12-lead ECG, followed by risk stratification to guide further management. 1
Initial Evaluation
History
- Focus on specific circumstances:
- Events before the attack (position, activity, predisposing factors)
- Onset of attack (presence of prodrome, symptoms)
- During the attack (duration, color, breathing pattern, movements, injury)
- End of attack (confusion, muscle pain, skin color, urination)
- Background information (previous episodes, comorbidities, family history)
Physical Examination
- Complete cardiovascular examination
- Orthostatic blood pressure measurements in lying, sitting, and standing positions
- Neurological examination when indicated
12-lead ECG
- Mandatory for all patients with syncope (Class I recommendation)
- Assess for:
- Arrhythmias
- Conduction abnormalities
- QT interval abnormalities
- Pre-excitation
- Brugada pattern
Risk Stratification
High-Risk Features (requiring hospitalization)
- Age >60 years
- Male sex
- Known ischemic/structural heart disease or arrhythmia
- Brief/absent prodrome
- Syncope during exertion or in supine position
- Low number of episodes
- Abnormal cardiac examination
- Family history of inheritable conditions or premature SCD
Low-Risk Features (can be managed as outpatients)
- Younger age
- No known cardiac disease
- Syncope only in standing position
- Clear positional trigger
- Typical prodrome present
- Specific situational triggers
- Frequent recurrence with similar characteristics
Additional Testing Based on Initial Evaluation
Cardiac Evaluation
Echocardiogram: Perform when there is known heart disease or suspicion of structural heart disease (Class IIa, B-NR) 1
- Note: Echocardiography has not been shown to provide additional useful information in patients without clinical evidence of heart disease 2
ECG Monitoring: Immediate monitoring when arrhythmic syncope is suspected
- Options include:
- Holter monitoring
- External loop recorder
- Implantable loop recorder (for recurrent unexplained syncope)
- Options include:
Exercise Stress Testing: Recommended if syncope occurs during exertion (Class IIa, C-LD)
Electrophysiological Studies: Consider if arrhythmia is suspected and non-invasive tests are non-diagnostic
Autonomic/Reflex Evaluation
- Orthostatic Challenge: Perform when syncope is related to standing position or reflex mechanism is suspected
- Head-up Tilt Table Testing: Recommended for recurrent unexplained syncope, especially in younger patients
- Carotid Sinus Massage: Consider in patients >40 years
Important Caveats
Avoid unnecessary testing:
- Routine comprehensive laboratory testing has low diagnostic yield and is not recommended unless clinically indicated 1
- Neuroimaging should only be ordered if clinically indicated
- Basic laboratory tests should only be performed if clinically indicated
Diagnostic yield:
Specialized care:
- Syncope units have been shown to improve diagnosis rates while reducing costs 4
- Consider referral to specialized care for recurrent or unexplained syncope
Follow-up:
- For patients with unexplained syncope after initial evaluation, risk stratification should guide further management
- Low-risk patients with a single episode can often be managed as outpatients
- High-risk patients should be hospitalized for further evaluation
By following this structured approach to syncope evaluation, clinicians can efficiently diagnose the underlying cause while avoiding unnecessary testing and hospital admissions, ultimately improving patient outcomes and reducing healthcare costs.