Recommended Workup for Syncopal Episodes
The initial evaluation of syncope should include a detailed history, physical examination with orthostatic vital signs, and a 12-lead ECG, which can establish diagnosis in most patients without requiring extensive testing. 1, 2
Initial Evaluation
History
The history should focus on:
Circumstances before the attack:
- Position (supine, sitting, standing)
- Activity (rest, change in posture, during/after exercise, during/after urination, defecation, cough, swallowing)
- Predisposing factors (crowded/warm places, prolonged standing, post-prandial period)
- Precipitating events (fear, pain, neck movements) 1
Onset of attack:
- Presence of prodrome: nausea, vomiting, feeling warm, sweating, aura, blurred vision
- Palpitations (suggesting arrhythmic cause) 1
During the attack (from witnesses):
- Way of falling
- Skin color (pallor, cyanosis, flushing)
- Duration of loss of consciousness
- Breathing pattern
- Movements (tonic, clonic, minimal myoclonus) 1
End of attack:
- Post-event symptoms (confusion, muscle aches, injury, chest pain, palpitations, incontinence) 1
Background information:
Physical Examination
- Orthostatic vital signs (measure BP and HR supine, then after 1 and 3 minutes of standing) 1, 2
- Cardiovascular examination (murmurs, gallops, rubs indicating structural heart disease)
- Basic neurological examination 1
Initial Testing
- 12-lead ECG (Class I recommendation) 1
- Laboratory tests:
- Complete blood count (for anemia)
- Electrolytes
- BUN/creatinine (hydration status)
- Thyroid function tests
- Ferritin (if anemia present) 2
Risk Stratification
High-Risk Features (Suggesting Cardiac Syncope)
- Age >60 years
- Male sex
- Known heart disease, structural heart disease, previous arrhythmias
- Brief/absent prodrome or palpitations before syncope
- Syncope during exertion or in supine position
- Abnormal cardiac examination
- Family history of inheritable conditions or premature SCD
- Abnormal ECG 1
Features Suggesting Noncardiac Causes
- Younger age
- No known cardiac disease
- Syncope only when standing
- Positional change from supine/sitting to standing
- Prodromal symptoms (nausea, vomiting, feeling warm)
- Specific triggers (dehydration, pain, distress)
- Situational triggers (cough, laugh, micturition, defecation)
- Recurrent episodes with similar characteristics 1
Additional Testing Based on Initial Evaluation
For Suspected Cardiac Syncope
- Echocardiography (if structural heart disease suspected)
- Stress testing (if syncope during/after exercise or suspected ischemia)
- Ambulatory cardiac monitoring:
For Suspected Neurally-Mediated Syncope
- Tilt table testing (especially in recurrent episodes)
- Carotid sinus massage (in patients >40 years)
- Autonomic function testing 1, 2
For Syncope with Specific Triggers
- For syncope during neck turning: carotid sinus massage
- For post-effort syncope: stress testing and echocardiography 1
Common Pitfalls to Avoid
Overuse of diagnostic tests without proper initial evaluation, leading to unnecessary costs and potential misdiagnosis 2
Misdiagnosis of seizures as syncope - look for post-ictal confusion and tongue biting 2
Failure to identify medication-induced syncope - review all medications, especially antihypertensives, antidepressants, and QT-prolonging agents 1, 2
Missing life-threatening causes of syncope such as structural heart disease and arrhythmias 2
Premature cardiac pacing without adequate documentation of bradyarrhythmia 2
By following this structured approach to syncope evaluation, clinicians can efficiently diagnose the cause in many patients during the initial assessment, appropriately risk-stratify patients for further management, and avoid unnecessary testing while ensuring that potentially serious causes are not missed.