What is the initial workup for a patient presenting with syncope (loss of consciousness)?

Initial Workup for Syncope

The initial evaluation of a patient with syncope must include a detailed history, physical examination with orthostatic blood pressure measurements, and a 12-lead ECG to establish diagnosis, determine etiology, and assess risk of adverse outcomes. 1, 2

Initial Assessment Components

History

• Obtain detailed information about circumstances before the attack:

  • Position (supine, sitting, or standing) 2
  • Activity (rest, posture change, during/after exercise, during/after urination, defecation, cough, swallowing) 2
  • Predisposing factors (crowded/warm places, prolonged standing, post-prandial period) 2
  • Precipitating events (fear, pain, neck movements) 2

• Document onset symptoms:

  • Presence of prodrome (nausea, vomiting, abdominal discomfort, feeling cold, sweating, aura, neck/shoulder pain, blurred vision, dizziness) 2
  • Palpitations before syncope (suggests arrhythmic cause) 2

• Obtain eyewitness account of the event:

  • Manner of falling (slumping vs. kneeling over) 2
  • Skin color changes (pallor, cyanosis, flushing) 2
  • Duration of loss of consciousness 2
  • Breathing pattern (snoring) 2
  • Movement patterns (tonic, clonic, minimal myoclonus, automatism) 2

• Assess recovery phase:

  • Post-event symptoms (confusion, muscle aches, chest pain, palpitations) 2
  • Presence of injury or incontinence 2

• Review relevant background information:

  • Family history of sudden death or congenital heart disease 2
  • Previous cardiac disease 2
  • Neurological conditions (Parkinsonism, epilepsy) 2
  • Medications (antihypertensives, antiarrhythmics, QT-prolonging agents) 2
  • Pattern of recurrent episodes 2

Physical Examination

• Complete cardiovascular examination:
  • Heart rate and rhythm 1
  • Presence of murmurs, gallops, or rubs that may indicate structural heart disease 1
  • Orthostatic blood pressure measurements in lying, sitting, and standing positions 1, 2
  • Carotid sinus massage in patients over 40 years (when appropriate) 2

Initial Diagnostic Testing

• 12-lead ECG in all patients 2, 1
• Look for specific ECG abnormalities suggesting arrhythmic syncope:
  • Bifascicular block 2
  • Conduction abnormalities 2
  • Evidence of ischemia 2
  • Long or short QT intervals 3
  • Brugada pattern 3
  • Pre-excitation patterns 3

Risk Stratification

High-Risk Features (Consider Admission)

• Age >60 years 1
• Known heart disease 1
• Abnormal ECG 2
• Brief or absent prodrome 1
• Syncope during exertion or in supine position 1
• Family history of inheritable conditions or premature sudden cardiac death 1
• Abnormal cardiac examination 1
• History of heart failure or structural heart disease 2
• Low blood pressure (systolic BP <90 mmHg) 2
• High OESIL score (≥2) or EGSYS score (≥3) 2

Low-Risk Features (Consider Outpatient Management)

• Younger age 1
• No known cardiac disease 1
• Normal ECG 2
• Syncope only when standing 1
• Clear prodromal symptoms 1
• Specific situational triggers 1
• Recurrent episodes with similar characteristics 2

Additional Testing Based on Initial Evaluation

• Echocardiogram when:

  • Structural heart disease is suspected 2, 1
  • Abnormal cardiac examination 1
  • Abnormal ECG suggesting structural heart disease 2

• Cardiac monitoring when:

  • Arrhythmic syncope is suspected 2
  • Selection based on frequency and nature of events 1

• Exercise stress testing when:

  • Syncope occurred during or shortly after exertion 1

• Orthostatic challenge testing when:

  • Syncope is related to standing position 2
  • Orthostatic hypotension is suspected 2

• Targeted blood tests based on clinical assessment:

  • Complete blood count if anemia or bleeding suspected 4
  • Electrolytes if electrolyte imbalance or dehydration suspected 4
  • Glucose if hypoglycemia suspected 4

Common Pitfalls to Avoid

• Failing to distinguish syncope from non-syncopal causes of transient loss of consciousness (seizures, metabolic disorders, head trauma) 1, 5
• Ordering comprehensive laboratory testing without clinical indication 1
• Overlooking orthostatic hypotension as a potential cause of syncope 1
• Neglecting to perform orthostatic blood pressure measurements 2
• Overreliance on neuroimaging, which has low diagnostic yield unless focal neurological findings are present 4
• Failing to recognize high-risk features that warrant hospital admission 2
• Dismissing presyncope, which carries similar prognostic implications as syncope 4