From the Guidelines
Near syncope and presyncope are considered the same condition, characterized by a transient, self-limited loss of consciousness or a cognitive state in which one lacks awareness of oneself and one’s situation, with an inability to respond to stimuli, but without complete loss of consciousness. According to the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1, presyncope (near-syncope) is defined as a cognitive state in which one lacks awareness of oneself and one’s situation, with an inability to respond to stimuli. The underlying mechanism of presyncope is presumed to be cerebral hypoperfusion, similar to syncope. Some key points to consider about presyncope (near-syncope) include:
- It is a self-limited condition that can be caused by various factors, including dehydration, medication side effects, heart rhythm abnormalities, orthostatic hypotension, or vasovagal reactions 1.
- Symptoms of presyncope can include dizziness, weakness, visual changes, nausea, and sweating, which typically last seconds to minutes 1.
- If presyncope occurs, it is essential to sit or lie down immediately to increase blood flow to the brain and prevent progression to full syncope.
- Recurrent episodes of presyncope warrant medical evaluation to identify underlying causes, which might require specific treatments such as medication adjustments, increased fluid intake, compression stockings, or management of underlying cardiac or neurological conditions 1. The physiological mechanism of presyncope involves temporary cerebral hypoperfusion that's not severe or prolonged enough to cause complete loss of consciousness, distinguishing it from syncope (fainting) 1.
From the Research
Definition and Comparison of Near Syncope and Presyncope
- Near syncope and presyncope are often used interchangeably to describe a condition where a person feels like they are about to lose consciousness but does not actually lose consciousness 2.
- Presyncope is characterized by the same prodromal symptoms as syncope, but without the actual loss of consciousness 3.
- Both near syncope and presyncope are associated with a risk of adverse outcomes, including hemorrhage, cardiac ischemia, and sepsis 2.
Risk of Adverse Outcomes
- Studies have shown that patients with near syncope or presyncope are at risk of adverse outcomes, including critical interventions and hospitalization 3, 2.
- The risk of adverse outcomes for near syncope and presyncope is similar to that of syncope, with a prevalence of short-term serious outcomes ranging from 4% to 27% 3, 2.
- The most common adverse outcomes for near syncope and presyncope include hemorrhage, bradydysrhythmia, alteration in antidysrhythmics, and sepsis 2.
Diagnosis and Management
- The diagnosis of near syncope and presyncope can be challenging, and a detailed initial evaluation with medical history, physical examination, and resting electrocardiogram is recommended 4.
- Management of patients with near syncope and presyncope should focus on improving symptoms and functional status, and may include lifestyle modifications, physical counter-pressure maneuvers, and pharmacologic interventions 4.
- Further research is needed to improve the treatment of patients with near syncope and presyncope, and to determine the best approach to management 2.