What is the diagnostic workup for syncope (fainting)?

From the Guidelines

The workup for syncope begins with a thorough history and physical examination, focusing on the circumstances surrounding the event, prodromal symptoms, and any associated features, as recommended by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1. The initial evaluation should include orthostatic vital signs, a 12-lead ECG, and basic laboratory tests (complete blood count, electrolytes, glucose, and renal function) to identify potential causes of syncope.

• The history should focus on the key features listed in Table 2.1 of the European Heart Journal guidelines, including predisposing factors, precipitating events, and accompanying symptoms 1.
• The physical examination should include cardiovascular and neurological signs, as well as orthostatic hypotension, to guide the subsequent evaluation strategy. For patients with suspected cardiac syncope, additional tests may include:
• Echocardiography to evaluate cardiac structure and function
• Ambulatory cardiac monitoring (Holter monitor for 24-48 hours or event recorder for 2-4 weeks) to detect arrhythmias
• Exercise stress testing to evaluate for ischemia or arrhythmias If neurological causes are suspected, brain imaging (CT or MRI) and electroencephalography may be appropriate.
• For recurrent unexplained syncope, tilt-table testing can help diagnose vasovagal syncope, while implantable loop recorders may be used for long-term monitoring in cases of infrequent episodes. Specialized tests like electrophysiology studies are reserved for patients with suspected arrhythmias or structural heart disease, as recommended by the European Heart Journal guidelines 1. The workup should be tailored to the patient's presentation, with cardiac evaluation prioritized in older patients or those with known heart disease, as cardiac syncope carries a higher mortality risk compared to neurally mediated or orthostatic syncope 1.

From the Research

Syncope Workup

The workup for syncope involves a thorough approach to identify the underlying cause and risk stratification. The following steps are involved in the workup:

• History-taking: remains the most important aspect of the clinical assessment 2
• Physical examination: including orthostatic blood pressure measurements 3, 2
• Electrocardiographic results: to identify potential cardiac causes of syncope 3, 4
• Risk stratification: to identify patients at higher risk of adverse outcomes from cardiac syncope 3, 5
• Additional testing: may be considered if the findings are inconclusive and indicate possible adverse outcomes, such as:
  • Prolonged electrocardiographic monitoring 3, 5
  • Stress testing 3
  • Echocardiography 3, 4
  • Neuroimaging: only when findings suggest a neurologic event or a head injury is suspected 3, 5
  • Laboratory tests: may be ordered based on history and physical examination findings 3, 5

Classification of Syncope

Syncope can be classified into three main categories:

• Cardiac syncope: due to a cardiac disorder, such as arrhythmias or structural heart disease 6, 3, 4
• Reflex (neurogenic) syncope: due to a reflex mechanism, such as vasovagal syncope or situational syncope 5, 2
• Orthostatic hypotension: due to an abnormal drop in systolic blood pressure upon standing 5, 2

Management of Syncope

The management of syncope depends on the underlying cause and risk stratification. The main objectives of management are to:

• Prolong survival
• Limit physical injuries
• Prevent recurrences 2
• Address any exacerbating medication and provide general measures to increase blood pressure, such as physical counter-pressure manoeuvres 2
• Refer to a cardiologist for appropriate management if heart disease is found to be the cause of the syncope 2