From the Guidelines
Seated syncope is most commonly associated with dehydration, prolonged sitting, and certain medications, particularly antihypertensives, diuretics, vasodilators, and some psychiatric medications, as well as autonomic nervous system disorders and cardiovascular conditions, according to the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.
Key Risk Factors
- Dehydration
- Prolonged sitting
- Certain medications (antihypertensives, diuretics, vasodilators, and some psychiatric medications)
- Autonomic nervous system disorders
- Cardiovascular conditions (arrhythmias or structural heart disease)
- Anemia
- Advanced age
Underlying Mechanisms
Orthostatic hypotension is a common underlying mechanism, where blood pressure drops significantly when changing positions, leading to inadequate cerebral perfusion and loss of consciousness. Other contributing factors include:
- Prolonged fasting
- Alcohol consumption
- Hot environments
- Recent illness with fever or vomiting
High-Risk Populations
Patients with diabetes, Parkinson's disease, or other neurological conditions have higher risk due to autonomic dysfunction, as noted in the guidelines for the diagnosis and management of syncope 1.
Prevention Strategies
To prevent seated syncope, individuals should:
- Stay well-hydrated
- Change positions slowly
- Avoid prolonged sitting
- Consider compression stockings if recommended by a healthcare provider
- Take medications as prescribed with appropriate timing Those with recurrent episodes should keep a symptom diary noting circumstances surrounding each event to help identify triggers, as suggested in the European Heart Journal guidelines 1.
From the Research
Seated Syncope Risk Factors
- The primary classifications of syncope are cardiac, reflex (neurogenic), and orthostatic 2
- Evaluation focuses on history, physical examination (including orthostatic blood pressure measurements), and electrocardiographic results 2
- Risk stratification tools, such as the Canadian Syncope Risk Score, may be beneficial in determining the risk of adverse outcomes 2
- The prognosis of patients with reflex and orthostatic syncope is good; cardiac syncope is more likely to be associated with adverse outcomes 2
Diagnosis and Management
- A thorough history and physical examination including orthostatic assessment are crucial for making the diagnosis 3
- Short-term risk assessment should be performed to determine the need for admission 3
- In patients with suspected cardiac syncope, monitoring is indicated until a diagnosis is made 3
- In patients with suspected reflex syncope or orthostatic hypotension, outpatient evaluation with tilt-table testing is appropriate 3
Risk Stratification
- Immediate risk stratification should be applied whenever syncope occurs, especially in the Emergency Department 4
- Short- and long-term syncope prognosis is affected not only by its mechanism but also by presence of concomitant conditions, especially cardiovascular disease 4
- Current European Society of Cardiology syncope guidelines recommend an initial syncope workup based on detailed patient's history, physical examination supine and standing blood pressure, resting ECG, and laboratory tests, including cardiac biomarkers, where appropriate 4
- Subsequent risk stratification based on screening of features aims to identify three groups: high-, intermediate- and low-risk 4