From the Guidelines
A pre-syncope workup involves a comprehensive evaluation to determine the cause of near-fainting episodes, starting with a detailed medical history and physical examination, including orthostatic measurements, and may include laboratory tests, cardiac evaluation with ECG and ambulatory monitoring, and additional tests such as echocardiography, exercise stress testing, EEG, or neuroimaging as needed. The workup begins with a detailed medical history focusing on the circumstances of pre-syncope events, including triggers, position changes, associated symptoms, and medication use 1. A thorough physical examination follows, with vital signs assessment including orthostatic measurements (checking blood pressure and heart rate while lying, sitting, and standing), cardiovascular examination, and neurological assessment. Laboratory tests typically include complete blood count, basic metabolic panel, cardiac enzymes, and thyroid function tests to rule out anemia, electrolyte abnormalities, cardiac injury, and thyroid disorders.
- Cardiac evaluation is essential, with a 12-lead ECG to assess for arrhythmias, conduction abnormalities, or ischemic changes, and often ambulatory cardiac monitoring (Holter or event monitor) for 24 hours to 30 days depending on symptom frequency 1.
- Additional cardiac tests may include echocardiography to evaluate structural heart disease and exercise stress testing if exertional symptoms are present.
- For suspected neurological causes, electroencephalography (EEG) or neuroimaging might be ordered.
- Tilt-table testing may be performed to diagnose vasovagal syncope by reproducing symptoms under controlled conditions. This comprehensive approach is necessary because pre-syncope can result from various underlying conditions including cardiac arrhythmias, structural heart disease, orthostatic hypotension, vasovagal reactions, or neurological disorders, and identifying the specific cause guides appropriate treatment 1.
From the Research
Pre-Syncope Workup
A pre-syncope workup entails a thorough evaluation to determine the cause of syncope, which is an abrupt, transient, and complete loss of consciousness associated with an inability to maintain postural tone 2. The workup includes:
- History-taking, which remains the most important aspect of the clinical assessment 3
- Physical examination, including orthostatic blood pressure measurements 2, 3
- Electrocardiographic results, which may disclose an arrhythmia associated with a high likelihood of syncope 4
- Laboratory tests, which may be ordered based on history and physical examination findings 2
Classification of Syncope
Syncope can be classified into three primary categories:
- Cardiac syncope, which is more likely to be associated with adverse outcomes 2
- Reflex (neurogenic) syncope, which includes vasovagal syncope, situational syncope, carotid sinus syncope, and atypical reflex syncope 3
- Orthostatic syncope, which is caused by an abnormal drop in systolic blood pressure upon standing 3
Risk Stratification
Risk stratification is crucial in determining the disposition of high- and low-risk patients 5. Patients with a potential malignant cause, such as a cardiac or neurologic condition, should be treated and admitted, while those with benign causes can be safely discharged 5. Risk stratification tools, such as the Canadian Syncope Risk Score, may be beneficial in this decision 2.
Additional Testing
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 2. Neuroimaging should be ordered only when findings suggest a neurologic event or a head injury is suspected 2. Tilt-table testing may be appropriate for patients with suspected reflex syncope or orthostatic hypotension 6.