From the Guidelines
Evaluation of syncope in the clinic should follow a systematic approach, prioritizing risk stratification to determine the need for hospitalization versus outpatient management, as recommended by the 2017 ACC/AHA/HRS guideline 1. The initial evaluation should include a thorough history, physical examination, and 12-lead ECG for all patients. The history should focus on circumstances surrounding the event, prodromal symptoms, position at onset, duration, and recovery pattern.
- Key components of the physical examination include:
- Orthostatic vital signs (measuring blood pressure and heart rate supine and after 1-3 minutes of standing)
- Cardiac examination
- Neurological assessment High-risk features warranting admission include syncope with chest pain, abnormal ECG, history of heart failure or structural heart disease, family history of sudden cardiac death, syncope during exertion, or severe injury, as outlined in the guideline 1. For patients with suspected cardiac syncope, additional testing may include:
- Echocardiography
- Ambulatory cardiac monitoring (Holter for 24-48 hours or event monitors for 2-4 weeks)
- Exercise stress testing For recurrent unexplained syncope, consider:
- Tilt-table testing to evaluate for vasovagal syncope
- Implantable loop recorders for long-term monitoring (up to 3 years) Treatment depends on the underlying cause:
- Vasovagal syncope often responds to increased salt and fluid intake (2-3L daily), compression stockings, and medications like midodrine (2.5-10mg three times daily) or fludrocortisone (0.1-0.2mg daily) in refractory cases
- Orthostatic hypotension management includes similar measures plus careful review of medications that may exacerbate symptoms
- Cardiac syncope requires specific treatment of the underlying arrhythmia or structural abnormality, which may include antiarrhythmic medications, pacemaker, or implantable cardioverter-defibrillator placement, as recommended by the guideline 1. Patient education about recognizing prodromal symptoms and assuming a supine position when symptoms occur is crucial for preventing injuries from syncopal episodes. Hospital evaluation and treatment are recommended for patients presenting with syncope who have a serious medical condition potentially relevant to the cause of syncope identified during initial evaluation, according to the 2017 ACC/AHA/HRS guideline 1.
From the Research
Evaluation of Syncope
- Syncope is defined as an abrupt, transient, and complete loss of consciousness associated with an inability to maintain postural tone, with rapid and spontaneous recovery 2, 3.
- The primary classifications of syncope are cardiac, reflex (neurogenic), and orthostatic 2.
- Evaluation of syncope focuses on history, physical examination (including orthostatic blood pressure measurements), and electrocardiographic results 2, 3.
Diagnostic Approach
- A thorough history and physical examination, including orthostatic assessment, are crucial for making the diagnosis of syncope 3.
- Short-term risk assessment should be performed to determine the need for admission, with high-risk patients requiring inpatient evaluation and low-risk patients suitable for outpatient evaluation 3, 4.
- Risk stratification tools, such as the Canadian Syncope Risk Score, may be beneficial in informing decisions regarding hospital admission 2.
Management of Syncope
- Patients with suspected cardiac syncope require monitoring until a diagnosis is made, while those with suspected reflex syncope or orthostatic hypotension may undergo outpatient evaluation with tilt-table testing 3.
- Syncope units have been shown to improve the rate of diagnosis while reducing cost, and are highly recommended 3.
- Midodrine, a specific alpha-1-agonist, has been shown to be effective and safe in the treatment of neurogenic orthostatic hypotension, a common confounder of vasovagal syncope 5, 6.
Special Considerations
- Neuroimaging should only be ordered 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.
- The prognosis of patients with reflex and orthostatic syncope is generally good, while cardiac syncope is more likely to be associated with adverse outcomes 2.