What is the 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 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.

Key Components of the Workup

• Initial testing should include orthostatic vital signs, an electrocardiogram (ECG), and basic laboratory tests such as complete blood count, basic metabolic panel, and cardiac enzymes if cardiac etiology is suspected.
• 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), and exercise stress testing.
• If neurological causes are suspected, brain imaging (CT or MRI) and electroencephalography (EEG) may be appropriate.
• For recurrent unexplained syncope, tilt-table testing can help diagnose vasovagal syncope, and electrophysiology studies may be considered for suspected arrhythmias.
• Carotid sinus massage may be performed in older patients with suspected carotid sinus hypersensitivity, though this should be done with caution and cardiac monitoring, as noted in the guidelines 1.

Tailoring the Workup to the Patient's Risk Factors

• The workup should be tailored to the patient's risk factors, with more extensive evaluation for those with heart disease, abnormal ECG, syncope during exertion, family history of sudden cardiac death, or absence of prodromal symptoms, as these suggest higher risk of cardiac causes requiring urgent intervention 1.
• The 2017 ACC/AHA/HRS guideline provides a comprehensive approach to the evaluation and management of patients with syncope, emphasizing the importance of a thorough history and physical examination, as well as the use of diagnostic tests to determine the underlying cause of syncope 1.

From the Research

Initial Evaluation

• The initial evaluation of a patient with syncope should include a thorough history and physical examination, including orthostatic assessment 2, 3.
• The classification of syncope is based on the underlying pathophysiological mechanism causing the event, and includes cardiac, orthostatic, and reflex (neurally mediated) mechanisms 2, 4.
• The primary objectives of management are to prolong survival, limit physical injuries, and prevent recurrences 2.

Diagnostic Approach

• A structured approach to the patient with syncope is required, including history-taking, physical examination, and electrocardiographic results 4, 3.
• The diagnostic yield of electrophysiological study in detecting the cause of syncope depends highly on the pretest probability 5.
• Short-term risk assessment should be performed to determine the need for admission, and risk stratification tools, such as the Canadian Syncope Risk Score, may be beneficial in this decision 4, 3.

Testing and Referral

• Additional testing, such as prolonged electrocardiographic monitoring, stress testing, and echocardiography, may be beneficial in patients at higher risk of adverse outcomes from cardiac syncope 4, 5.
• Neuroimaging should be ordered only when findings suggest a neurologic event or a head injury is suspected 4.
• Patients with suspected cardiac syncope should be referred to a cardiologist for appropriate management, and syncope units have been shown to improve the rate of diagnosis while reducing cost 2, 3.

Management

• Patients with life-threatening causes of syncope should be managed urgently and appropriately 2.
• 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 2.
• The prognosis of patients with reflex and orthostatic syncope is good, while cardiac syncope is more likely to be associated with adverse outcomes 4.