What is the appropriate workup and management for a patient presenting with syncope?

Syncope Workup: A Structured Approach

The initial evaluation of a patient with syncope must include a detailed history, physical examination, orthostatic blood pressure measurements, and a 12-lead ECG to determine the cause and assess risk of adverse outcomes. 1

Initial Evaluation

History

Focus on identifying key features that differentiate between cardiac and non-cardiac causes:

Features suggesting cardiac syncope:

• Older age (>60 years)
• Male sex
• Known heart disease (ischemic, structural, arrhythmias)
• Brief or absent prodrome
• Syncope during exertion or while supine
• Palpitations preceding loss of consciousness
• Family history of sudden cardiac death
• Low number of episodes (1-2)
• Abnormal cardiac examination 1

Features suggesting neurally-mediated syncope:

• Younger age
• No known cardiac disease
• Syncope only when standing
• Prodromal symptoms (nausea, warmth, sweating)
• Specific triggers (dehydration, pain, medical environment)
• Situational triggers (cough, micturition, defecation)
• Frequent recurrence with similar characteristics 1

Features suggesting orthostatic hypotension:

• Syncope after standing up
• Temporal relationship with medication changes
• Prolonged standing in hot/crowded places
• Presence of autonomic neuropathy or Parkinsonism 1

Physical Examination

• Complete cardiovascular examination
• Orthostatic vital signs (decrease in systolic BP ≥20 mmHg or to <90 mmHg defines orthostatic hypotension)
• Carotid sinus massage in patients >40 years (if no contraindications)

12-Lead ECG

• Mandatory for all patients with syncope
• Look for arrhythmias, conduction abnormalities, QT prolongation, Brugada pattern, or evidence of ischemia 1

Risk Stratification and Disposition

After initial evaluation, risk stratification should guide disposition:

High-risk features requiring hospital admission:

• Severe structural or coronary heart disease
• ECG features suggesting arrhythmic syncope:
  • Sinus bradycardia <40 bpm
  • Sinoatrial blocks or pauses >3 seconds
  • Mobitz II or third-degree AV block
  • Alternating bundle branch block
  • Rapid SVT or VT
  • Pacemaker malfunction 1

Intermediate-risk patients:

• Consider structured ED observation protocol to reduce hospital admission 1

Low-risk patients:

• Patients with presumptive reflex-mediated syncope without serious medical conditions can be managed as outpatients 1
• Selected patients with suspected cardiac syncope without serious medical conditions may be managed as outpatients 1

Further Diagnostic Testing

Cardiac Evaluation

For patients with suspected cardiac syncope:

1. Echocardiography:

   • Indicated when structural heart disease is suspected 1
   • Not useful if initial evaluation doesn't suggest cardiac etiology

2. Cardiac Monitoring:

   • Continuous ECG monitoring for hospitalized patients 1
   • For ambulatory patients with suspected arrhythmic etiology:
     • Holter monitor (24-48 hours)
     • External loop recorder
     • Patch recorder
     • Mobile cardiac outpatient telemetry
     • Implantable cardiac monitor (for recurrent unexplained episodes) 1

3. Exercise Stress Testing:

   • Useful when syncope occurs during or after exertion 1

4. Advanced Imaging:

   • CT or MRI may be useful in selected patients with suspected cardiac etiology 1

Neurally-Mediated Syncope Evaluation

For patients with suspected reflex syncope:

1. Tilt Table Testing:

   • Useful for diagnosing vasovagal syncope
   • Consider for recurrent unexplained syncope 1

2. Carotid Sinus Massage:

   • Particularly in patients >40 years
   • Especially when syncope occurs with neck turning 1

Laboratory Testing

• Targeted blood tests based on clinical assessment 1
• Routine comprehensive laboratory testing is not useful 1
• Brain natriuretic peptide and high-sensitivity troponin may be considered if cardiac cause is suspected, but usefulness is uncertain 1

Common Pitfalls to Avoid

1. Overuse of diagnostic tests:

   • Routine cardiac imaging is not useful unless cardiac etiology is suspected 1
   • Avoid comprehensive laboratory testing in all patients 1

2. Misdiagnosis of seizure vs. syncope:

   • Syncope typically has brief or no postictal confusion
   • Seizures often have prolonged postictal state and abnormal movements during event

3. Missing cardiac syncope:

   • Cardiac causes have higher mortality risk
   • Always obtain ECG in all syncope patients
   • Consider cardiac monitoring in patients with structural heart disease

4. Failure to recognize orthostatic hypotension:

   • Always check orthostatic vital signs
   • Review medications that can cause hypotension

5. Inappropriate disposition:

   • Patients with high-risk features require admission
   • Low-risk patients with clear vasovagal syncope can be safely discharged

By following this structured approach to syncope evaluation, clinicians can efficiently diagnose the cause of syncope, appropriately risk-stratify patients, and implement targeted management strategies to reduce morbidity and mortality.