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 this approach has been endorsed by various medical societies 1. The initial evaluation should include measurement of postural changes in blood pressure to diagnose orthostatic-related syncope and a detailed neurologic history and physical examination to exclude symptoms or signs of a separate neurologic process.

• Key components of the initial assessment include:
  • A detailed cardiac examination assessing for structural heart disease
  • Identification of patient characteristics associated with an increased risk of cardiac-related syncope, such as age >60 years, male gender, known underlying congenital or acquired cardiac disease, palpitations or other cardiac-related symptoms prior to syncopal episode, syncope during exertion, syncope in supine position, low number of prior syncopal episodes, and family history of sudden cardiac death 1
• Initial testing should include:
  • Orthostatic vital signs
  • Electrocardiogram (ECG) to detect arrhythmias or abnormality indicative of higher risk for arrhythmia (eg, prolonged QT interval) 1
  • Basic laboratory tests (complete blood count, electrolytes, glucose, and renal function)
• Brain CT and MRI should be avoided in uncomplicated syncope, as they have a low yield of acute abnormality and are not endorsed by major medical societies 1.
• Additional testing, such as echocardiography, ambulatory cardiac monitoring, and exercise stress testing, should be limited to select patients based on clinical assessment, as nonfocused testing does not improve diagnostic yield but increases hospitalization rate and cost 1.
• The workup should be tailored to the patient's presentation, with cardiac causes prioritized due to their association with higher mortality.
• Treatment depends on the underlying cause, ranging from simple measures like increased fluid intake and salt consumption for vasovagal syncope to medication adjustments for orthostatic hypotension or specific interventions for cardiac arrhythmias.

From the Research

Syncope Workup

• The evaluation of syncope focuses on history, physical examination (including orthostatic blood pressure measurements), and electrocardiographic results 2.
• The primary classifications of syncope are cardiac, reflex (neurogenic), and orthostatic 2, 3.
• A structured approach to the patient with syncope is required, with history-taking being the most important aspect of the clinical assessment 3.
• The classification of syncope is based on the underlying pathophysiological mechanism causing the event, and includes cardiac, orthostatic and reflex (neurally mediated) mechanisms 3.

Diagnostic Tests

• Additional testing may be considered if the findings are inconclusive and indicate possible adverse outcomes 2.
• Prolonged electrocardiographic monitoring, stress testing, and echocardiography may be beneficial in patients at higher risk of adverse outcomes from cardiac syncope 2.
• Tilt-table testing, the active standing test, carotid sinus massage, electrophysiological testing, and the adenosine triphosphate (ATP) test may be useful in the evaluation of the basis of suspected syncope 4.
• An insertable subcutaneous loop recorder can provide prolonged ECG monitoring 5.

Risk Assessment

• Patients are designated as having lower or higher risk of adverse outcomes according to history, physical examination, and electrocardiographic results, which can inform decisions regarding hospital admission 2.
• Risk stratification tools, such as the Canadian Syncope Risk Score, may be beneficial in this decision; some tools include cardiac biomarkers as a component 2.
• Short-term risk assessment should be performed to determine the need for admission 6.

Management

• Patients with life-threatening causes of syncope should be managed urgently and appropriately 3.
• In patients with reflex or orthostatic syncope, it is important to address any exacerbating medication and provide general measures to increase blood pressure, such as physical counter-pressure manoeuvres 3.
• Where heart disease is found to be the cause of the syncope, a specialist opinion is warranted and where possible the problem should be corrected 3.