What is the appropriate workup for syncope (fainting)?

From the Guidelines

The workup for syncope should begin with a thorough history and physical examination, focusing on the circumstances surrounding the event, prodromal symptoms, and any associated features, as recommended by the American College of Radiology Appropriateness Criteria 1.

Initial Evaluation

Initial testing should include:

• Orthostatic vital signs
• A 12-lead ECG
• Basic laboratory tests (complete blood count, electrolytes, glucose, and renal function)

Additional Testing

For patients with suspected cardiac syncope, additional tests may include:

• Echocardiography
• Ambulatory cardiac monitoring (Holter monitor for 24-48 hours or event recorder for 2-4 weeks)
• Exercise stress testing If neurological causes are suspected, brain imaging (CT or MRI) and electroencephalography may be appropriate.

Specialized Tests

For recurrent unexplained syncope, tilt-table testing can help diagnose vasovagal syncope, while implantable loop recorders may be used for long-term monitoring (up to 3 years) in cases where arrhythmias are suspected but not captured on shorter-term monitoring. Specialized tests like electrophysiology studies should be considered for patients with structural heart disease or suspected arrhythmias, as recommended by the European Heart Journal 1.

Risk Stratification

The workup should be tailored to the patient's risk factors, with more urgent and comprehensive evaluation for those with heart disease, abnormal ECG findings, syncope during exertion, or family history of sudden cardiac death, as these suggest potentially life-threatening causes 1.

From the Research

Syncope Workup

• The goals of the clinical assessment of a patient with syncope are to identify the precise cause and to quantify the risk to the patient 2
• A structured approach to the patient with syncope is required, with history-taking being the most important aspect of the clinical assessment 2, 3
• The classification of syncope is based on the underlying pathophysiological mechanism causing the event, and includes:
  • Cardiac mechanisms
  • Orthostatic mechanisms
  • Reflex (neurally mediated) mechanisms, which can be further categorised into:
    • Vasovagal syncope
    • Situational syncope
    • Carotid sinus syncope
    • Atypical reflex syncope 2, 4, 5

Evaluation and Diagnostic Testing

• The initial assessment for all patients presenting with syncope includes a detailed history, physical examination, and electrocardiography 4, 5, 3
• Laboratory testing and neuroimaging have a low diagnostic yield and should be ordered only if clinically indicated 4, 5
• Electroencephalography (EEG) findings in syncope are similar and reflect cerebral hypoperfusion, regardless of the cause of syncope 6
• A 12-lead electrocardiogram (ECG) is the only instrumental test recommended for the initial evaluation of patients with suspected syncope, and may disclose an arrhythmia associated with a high likelihood of syncope 3

Risk Stratification and Management

• Patients with syncope can be designated as having lower or higher risk of adverse outcomes according to history, physical examination, and electrocardiographic results 4, 5
• Risk stratification tools, such as the Canadian Syncope Risk Score, may be beneficial in informing decisions regarding hospital admission 4
• The prognosis of patients with reflex and orthostatic syncope is good, while cardiac syncope is more likely to be associated with adverse outcomes 4, 5
• The treatment of neurally mediated and orthostatic hypotension syncope is largely supportive, although severe cases may require pharmacotherapy, while cardiac syncope may require cardiac device placement or ablation 5