From the Guidelines
Syncope investigations 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. These initial steps help determine the likely cause and guide further testing. For suspected cardiac syncope, additional tests include:
- 24-48 hour Holter monitoring or longer-term event recorders (2-4 weeks) for intermittent arrhythmias
- Echocardiography to assess structural heart disease, as recommended by the 2017 ACC/AHA/HRS guideline 1
- Exercise stress testing if exertional syncope is reported Tilt table testing is valuable for suspected vasovagal syncope, typically involving 60-80 degree tilting for 20-45 minutes, sometimes with provocative agents like nitroglycerin or isoproterenol. Carotid sinus massage may identify carotid sinus hypersensitivity in older patients but should be avoided in those with carotid bruits or recent stroke. Blood tests including complete blood count, electrolytes, glucose, and cardiac biomarkers can identify metabolic causes. For recurrent unexplained syncope, implantable loop recorders may be used for long-term monitoring (up to 3 years) as recommended by the 2004 European Heart Journal guidelines 1. Neurological investigations like EEG or brain imaging are only indicated when seizures or neurological causes are suspected, as stated in the 2021 ACR Appropriateness Criteria for syncope 1. This stepwise approach helps identify the underlying cause while minimizing unnecessary testing, as the etiology determines appropriate treatment and prognosis. It is essential to prioritize the most recent and highest quality study, which in this case is the 2017 ACC/AHA/HRS guideline 1, to ensure that the recommended investigations are based on the latest evidence. By following this approach, clinicians can provide optimal care for patients with syncope, reducing morbidity, mortality, and improving quality of life.
From the Research
Investigations for Syncope
The investigations for syncope (fainting) include:
- A careful history and physical examination to differentiate syncope from other conditions that may cause a loss of consciousness or falling 2, 3, 4, 5
- Electrocardiography (ECG) as part of the initial evaluation to identify potential cardiac causes of syncope 2, 3, 4, 5
- Orthostatic blood pressure measurements to assess for orthostatic hypotension 4, 5
- Additional testing based on the initial clinical evaluation, such as:
- Prolonged electrocardiographic monitoring, echocardiography, and exercise stress testing for patients with suspected cardiac syncope 2, 3, 4, 5
- Head-up tilt-table testing and carotid sinus massage for patients with suspected neurogenic reflex-mediated syncope 2
- Neuroimaging (e.g., head computed tomography, magnetic resonance imaging) for patients with suspected cerebrovascular causes of syncope or focal neurologic signs or symptoms 2, 4
- Laboratory tests (e.g., hemoglobin measurement) based on history and physical examination findings 4
- Risk stratification tools, such as the Canadian Syncope Risk Score, to inform decisions regarding hospital admission 4
Diagnostic Approach
The diagnostic approach to syncope involves:
- A standardized approach to reduce hospital admissions and medical costs, and increase diagnostic accuracy 3
- Use of clinical decision rules, such as the San Francisco Syncope Rule and the Risk Stratification of Syncope in the Emergency Department rule, to assess the short-term risk of death and the need for hospital admission 3, 5
- Consideration of the patient's risk factors, such as age, underlying organic heart disease, and abnormal ECG findings, to guide further evaluation and management 2, 3, 4, 5