Evaluation of syncope

Syncope is a sudden and transient loss of consciousness that is associated with loss of postural tone due to cerebral hypoperfusion. Syncope resolves spontaneously and completely without intervention. Precise incidence rates are difficult to determine and depend on the features of the population studied. In the United States, syncope accounts for approximately 1.1% of all emergency department visits and 2% of all hospital admissions from the emergency department.[1]Sun BC. Quality-of-life, health service use, and costs associated with syncope. Prog Cardiovasc Dis. 2013 Jan-Feb;55(4):370-75. https://www.sciencedirect.com/science/article/abs/pii/S0033062012001867?via%3Dihub http://www.ncbi.nlm.nih.gov/pubmed/23472773?tool=bestpractice.com [2]Centers for Disease Control and Prevention. ​National hospital ambulatory medical care survey: 2019 emergency department summary tables. Jul 2022 [internet publication]. https://stacks.cdc.gov/view/cdc/115748 ​​ Syncope can affect individuals of all ages, although the most common underlying etiologies vary significantly by age.

Although the pathophysiology of syncope is related to a transient decrease in cerebral blood flow, the causes of syncope are myriad and range from the benign to the life-threatening.

Physicians must identify patients with potentially life-threatening processes (e.g., dysrhythmias, pulmonary embolism, subarachnoid hemorrhage, acute coronary syndromes), patients who may require hospitalization and intervention (e.g., bradycardia or medication-induced orthostatic hypotension), and those with a more benign cause of syncope who can be discharged.[3]Probst MA, Su E, Weiss RE, et al. Clinical Benefit of Hospitalization for Older Adults With Unexplained Syncope: A Propensity-Matched Analysis. Ann Emerg Med. 2019 Aug;74(2):260-69. https://www.annemergmed.com/article/S0196-0644(19)30250-1/fulltext http://www.ncbi.nlm.nih.gov/pubmed/31080027?tool=bestpractice.com

The history and physical exam may identify an underlying cause of syncope in many patients. However, the lack of accurate historical information, and the fact that patients are often asymptomatic at the time of evaluation, combine to fuel diagnostic uncertainty.