What is the appropriate workup for syncope (fainting)?

From the Guidelines

The workup for syncope should begin with a thorough history, physical examination, and 12-lead ECG for all patients, as recommended by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1. The history should focus on circumstances surrounding the event, prodromal symptoms, position at onset, and any associated symptoms. Physical examination should include:

• Orthostatic vital signs
• Cardiovascular assessment
• Neurological evaluation If the initial evaluation suggests cardiac syncope, further testing should include:
• Echocardiography
• Ambulatory cardiac monitoring (24-hour Holter for frequent episodes or 30-day event monitor for infrequent episodes)
• Exercise stress testing if exertional syncope is suspected For suspected vasovagal syncope, tilt-table testing may be considered. If neurological causes are suspected, brain imaging (MRI or CT) and EEG may be appropriate, but should be avoided in uncomplicated syncope, as suggested by the ACR Appropriateness Criteria for syncope 1. Laboratory tests should include:
• Complete blood count
• Electrolytes
• Glucose
• Cardiac biomarkers For older adults or those with risk factors, carotid sinus massage may be performed to evaluate for carotid sinus hypersensitivity. Implantable loop recorders can be used for recurrent unexplained syncope. The workup should be tailored to the patient's presentation, with cardiac causes prioritized due to their association with higher mortality, as emphasized by the European Heart Journal guidelines on management of syncope 1. Treatment depends on the identified cause, ranging from simple measures like hydration and salt intake for vasovagal syncope to medication adjustments, pacemaker implantation, or specific treatments for underlying cardiac conditions.

From the Research

Syncope Workup

• The evaluation of syncope focuses on history, physical examination, and electrocardiographic results 2.
• A thorough history and physical examination, including orthostatic assessment, are crucial for making the diagnosis 3.
• The primary classifications of syncope are cardiac, reflex (neurogenic), and orthostatic 2, 4.
• The condition is common, resulting in about 1.7 million emergency department visits in 2019, with the immediate cause being cerebral hypoperfusion 2.

Diagnostic Approach

• History-taking remains the most important aspect of the clinical assessment 4.
• The classification of syncope is based on the underlying pathophysiological mechanism causing the event 4.
• A structured approach to the patient with syncope is required, including a careful initial examination and application of specialized syncope evaluation units and structured questionnaires for history taking 5.
• Short-term risk assessment should be performed to determine the need for admission, with inpatient evaluation needed for high-risk patients and outpatient evaluation recommended for low-risk patients 3.

Testing and Evaluation

• Electrocardiographic results are a key component of the evaluation, with certain electrocardiographic presentations providing a reason for the loss of consciousness and guiding early therapy and disposition 6.
• Prolonged electrocardiographic monitoring, stress testing, and echocardiography may be beneficial in patients at higher risk of adverse outcomes from cardiac syncope 2.
• Neuroimaging should be ordered only when findings suggest a neurologic event or a head injury is suspected 2.
• Laboratory tests may be ordered based on history and physical examination findings, such as hemoglobin measurement if gastrointestinal bleeding is suspected 2.

Risk Stratification

• 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, with some tools including cardiac biomarkers as a component 2.
• The prognosis of patients with reflex and orthostatic syncope is good, while cardiac syncope is more likely to be associated with adverse outcomes 2.