From the Guidelines
Syncope does not exclude POTS (Postural Orthostatic Tachycardia Syndrome). In fact, syncope or fainting can be a symptom of POTS in some patients. POTS is characterized by an abnormal increase in heart rate upon standing, often accompanied by symptoms like lightheadedness, palpitations, fatigue, and sometimes syncope. While not all POTS patients experience syncope, approximately 30-40% of individuals with POTS may have syncopal episodes during the course of their condition. The mechanism behind syncope in POTS involves inadequate cerebral perfusion when standing, despite the increased heart rate. This occurs because the excessive tachycardia may not effectively compensate for reduced venous return and cardiac output in the upright position. The presence of syncope might actually support a POTS diagnosis when it occurs in conjunction with other characteristic symptoms and the diagnostic criteria of heart rate increase of at least 30 beats per minute (or ≥40 bpm in those aged 12-19) within 10 minutes of standing, without orthostatic hypotension, as stated in the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.
Key Points
- POTS is a clinical syndrome characterized by frequent symptoms that occur with standing, an increase in heart rate of ≥30 bpm during a positional change from supine to standing, and the absence of orthostatic hypotension 1.
- Syncope can be a symptom of POTS, although it is relatively infrequent, and there is little evidence that the syncope is due to POTS 1.
- The diagnosis of POTS requires a thorough evaluation, often including tilt table testing, to differentiate POTS from other causes of syncope 1.
- Treatments that improve symptoms of POTS might decrease the occurrence of syncope, although this is unknown 1.
Diagnostic Criteria
- Heart rate increase of at least 30 beats per minute (or ≥40 bpm in those aged 12-19) within 10 minutes of standing, without orthostatic hypotension 1.
- Frequent symptoms that occur with standing, such as lightheadedness, palpitations, tremulousness, generalized weakness, blurred vision, exercise intolerance, and fatigue 1.
Management
- Proper diagnosis requires a thorough evaluation, often including tilt table testing, to differentiate POTS from other causes of syncope 1.
- Treatments that improve symptoms of POTS might decrease the occurrence of syncope, although this is unknown 1.
From the Research
Syncope and POTS
- Syncope, also known as fainting, is a symptom that can occur in various conditions, including postural orthostatic tachycardia syndrome (POTS) 2, 3.
- POTS is a condition characterized by a rapid heart rate and other symptoms that occur upon standing, while syncope is a sudden loss of consciousness caused by a lack of blood flow to the brain 4, 5.
Coexistence of Syncope and POTS
- Research suggests that syncope and POTS can coexist in some patients, with studies showing that patients with POTS may also experience syncope 3.
- A study published in 2011 found that 18 patients with POTS also had neurocardiogenic syncope, a type of syncope that is caused by a reflex of the nervous system 3.
- Another study published in 2020 discussed the diagnosis and management of POTS and neurally mediated syncope, highlighting the importance of recognizing and treating both conditions 2.
Diagnosis and Management
- The diagnosis of POTS and syncope typically involves a combination of medical history, physical examination, and diagnostic tests such as head-up tilt table testing 3, 4.
- Management of POTS and syncope may involve lifestyle modifications, such as increasing fluid and salt intake, as well as medications to raise blood pressure or slow heart rate 2, 5.
- In some cases, patients with refractory neurocardiogenic syncope may benefit from treatment with midodrine, a peripheral alpha-stimulating agent 6.