From the Guidelines
Presyncope is caused by temporary insufficient blood flow to the brain, resulting in lightheadedness and feeling faint without complete loss of consciousness, with common causes including orthostatic hypotension, vasovagal reactions, cardiac arrhythmias, and neurological conditions. The most recent and highest quality study, published in 2024 1, supports the use of physical counterpressure maneuvers (PCMs) to help prevent syncope in individuals experiencing presyncope.
Causes of Presyncope
- Orthostatic hypotension (blood pressure drop when standing)
- Vasovagal reactions (triggered by pain, fear, or standing for long periods)
- Cardiac arrhythmias (like bradycardia or tachycardia)
- Structural heart problems (aortic stenosis or hypertrophic cardiomyopathy)
- Medication side effects (antihypertensives, diuretics, nitrates, beta-blockers)
- Dehydration, anemia, and hypoglycemia
- Neurological conditions like seizures or migraines
Management of Presyncope
- Staying hydrated
- Changing positions slowly
- Avoiding triggers
- Medication adjustments
- Treating underlying conditions
- Using physical counterpressure maneuvers (PCMs) to help prevent syncope, as recommended by the 2024 American Heart Association and American Red Cross guidelines for first aid 1.
It is essential to note that while the evidence from 1 provides valuable insights into the definitions and classifications of syncope and presyncope, the most recent and highest quality study 1 takes precedence in guiding clinical practice. Therefore, the use of PCMs is a recommended first aid intervention to help prevent syncope in individuals experiencing presyncope.
From the FDA Drug Label
Central Nervous System Tiredness and dizziness have occurred in about 10 of 100 patients.
The causes of presyncope (near fainting) that can be associated with beta-blockers include dizziness and bradycardia (low heart rate), as well as hypotension (low blood pressure) 2.
- Dizziness is a common adverse effect, occurring in about 10 of 100 patients.
- Bradycardia has been reported, and can increase the risk of presyncope.
- Hypotension can also contribute to presyncope, and has been reported in some patients taking beta-blockers.
From the Research
Causes of Presyncope
The causes of presyncope, also known as near fainting, can be diverse and may signal serious underlying conditions 3, 4, 5, 6, 7. Some of the possible causes include:
- Cardiogenic presyncope, which can be caused by cardiac arrhythmias, structural cardiac diseases, or other cardiac conditions 6, 7
- Orthostatic hypotension, which can be caused by drugs, hypovolemia, primary or secondary autonomic failure, or other factors 4, 6
- Neurally mediated presyncope, which can include cardioinhibitory, vasodepressor, and mixed forms 4, 6
- Vasovagal presyncope, which is a type of neurally mediated presyncope 4, 5
- Carotid sinus hypersensitivity, which can cause presyncope 4
- Miscellaneous cardiovascular causes, such as systemic hypotension, arrhythmias, or drugs 4, 5
- Non-autonomic neurological causes, such as vestibular dysfunction or epilepsy 4, 6
- Psychiatric causes, such as anxiety or panic disorders 4, 5
- Unknown causes, which can account for a significant proportion of presyncope cases 4, 5
Diagnostic Approach
A thorough diagnostic approach is necessary to determine the underlying cause of presyncope 3, 4, 5, 6, 7. This may include:
- A detailed medical history and physical examination 6
- A 12-lead electrocardiogram (ECG) 6
- Blood testing, electroencephalogram (EEG), magnetic resonance imaging (MRI) of the brain, echocardiography, head-up tilt test, carotid sinus massage, Holter monitoring, and loop recorders, which may be obtained in specific contexts 6
- Autonomic function tests, which can help diagnose orthostatic hypotension and chronic autonomic failure 4