From the Guidelines
The workup for a patient with recurrent syncope should begin with a thorough history, physical examination, and 12-lead ECG, which together can identify the cause in up to 50% of cases. The history should focus on circumstances surrounding the episodes, prodromal symptoms, position at onset, duration, and post-event symptoms. Physical examination should include orthostatic vital signs (measuring blood pressure and heart rate supine, then after standing for 1-3 minutes), cardiac examination, and neurological assessment. Laboratory tests should include complete blood count, basic metabolic panel, and cardiac biomarkers if cardiac syncope is suspected. Additional cardiac testing may include 24-48 hour Holter monitoring for frequent episodes, 30-day event monitors or implantable loop recorders for infrequent episodes, and echocardiography to assess structural heart disease, especially if there are abnormal cardiac findings or family history of sudden death. Tilt-table testing may be useful when vasovagal syncope is suspected. Carotid sinus massage can be performed in patients over 40 without carotid bruits or history of cerebrovascular disease. Electroencephalography and brain imaging are indicated only when seizure activity is suspected or with focal neurological findings. Exercise stress testing should be considered for exertional syncope. This systematic approach helps identify the underlying cause, which may be reflex-mediated (vasovagal), orthostatic, cardiac (arrhythmic or structural), or neurologic, allowing for appropriate treatment and prevention of recurrence, as recommended by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.
Some key considerations in the workup include:
- Identifying predictors of recurrent syncope, such as aortic stenosis, impaired renal function, atrioventricular block, male sex, chronic obstructive pulmonary disorder, heart failure, atrial fibrillation, and orthostatic medications, as outlined in the 2017 ACC/AHA/HRS guideline 1.
- Recognizing the importance of a thorough history and physical examination in identifying the cause of syncope, as emphasized in the 2017 ACC/AHA/HRS guideline 1.
- Considering the use of physical counterpressure maneuvers (PCMs) to prevent syncope in patients with vasovagal or orthostatic syncope, as recommended in the 2019 American Heart Association and American Red Cross focused update for first aid 1.
Overall, a systematic and thorough approach to the workup of recurrent syncope is essential to identify the underlying cause and provide appropriate treatment to prevent recurrence and improve patient outcomes.
From the Research
Initial Evaluation
The workup for a patient with recurrent syncope begins with an initial evaluation consisting of:
- Careful history taking
- Physical examination, including orthostatic blood pressure measurement
- Electrocardiogram (ECG) 2, 3, 4, 5
Diagnostic Yield of Initial Evaluation
The diagnostic yield of the initial evaluation is approximately 50% 2. In cases where a satisfactory diagnosis is unknown or uncertain after initial assessment, additional clinical testing is needed.
Additional Diagnostic Tests
Additional diagnostic tests that may be used in the evaluation of syncope include:
- Tilt-table testing
- Active standing test
- Carotid sinus massage
- Electrophysiological testing
- Adenosine triphosphate (ATP) test 2
- Ambulatory ECG monitoring
- Angiography
- Exercise testing
- Imaging 2, 5
Selection of Diagnostic Tests
Diagnostic tests should be selected carefully and performed based on the pre-test probability inferred from the initial examination. Less invasive tests should be used first 2.
Risk Stratification
Several risk stratification tools, such as the Canadian Syncope Risk Score (CSRS) and the FAINT score, have been developed to predict the risk of adverse outcomes in patients with syncope. These tools can help identify patients who may be appropriate for discharge from the emergency department 6.
Hospital Admission
The decision to admit a patient with syncope to the hospital should be based on the presence of potentially life-threatening pathology and the need for further evaluation and intervention 6, 4, 5.