There are more than 1.2 million annual events of syncope in the United States that lead to an emergency department visit, resulting in 440,000 admissions and $2.4 billion in yearly hospital costs. Patients without a clear cause of syncope are frequently admitted for diagnostic testing. However, current practice is characterized by high variation, low diagnostic yield, exorbitant costs, and unclear improvement in outcomes.

To address these challenges, the 2017 American College of Cardiology (ACC)/American Heart Association (AHA) Syncope Guideline provides evidence-based recommendations.¹ The multidisciplinary writing committee included an emergency medicine representative, and the final recommendations were endorsed by ACEP and the Society for Academic Emergency Medicine. Specific recommendations relevant to emergency physicians are summarized below.

• Perform a detailed history, physical exam, and 12-lead ECG (COR I). These elements are the foundation of the syncope evaluation and guide all subsequent diagnostic and disposition decisions.
• Risk-stratify patients without a presumptive cause of syncope (COR I). Factors that may be associated with increased risk of death and serious medical outcomes include male gender, older age, absence of prodromal symptoms, exertional syncope, prior history of heart disease, and abnormal ECG. Multiple risk scores have been published, and it may be reasonable to use such scores to aid in risk stratification (COR IIa). However, there is no evidence that published risk scores perform better than unstructured clinical judgment.
• Admit patients with serious medical conditions identified in the emergency department (COR I).
• Discharge patients with presumptive vasovagal syncope (COR I). Patients with presumptive vasovagal etiology have similar long-term outcomes as risk-matched controls without syncope.
• For intermediate-risk patients with an unclear cause of syncope, consider a structured observation protocol as an alternative to inpatient admission (COR IIa). Two randomized trials suggest that a structured observation unit stay is safe and less costly than inpatient admission. It is important to note that this recommendation does not imply that all intermediate-risk patients require prolonged hospital-based evaluation.
• Consider an outpatient workup for suspected cardiac syncope (COR IIb). The expert opinion of the committee was that outpatient follow-up, without admission to an inpatient bed or observation unit, was a reasonable option in carefully selected patients with an acute presentation of syncope. For example, reliable patients who can follow up with their primary care providers or cardiologist within 48 hours may be reasonable candidates for an outpatient management strategy.
• Routine comprehensive laboratory testing, cardiac imaging, brain imaging, carotid artery imaging, and electroencephalogram testing are not recommended (COR III). A large amount of literature documents the low diagnostic yield of these tests in unselected patients. Diagnostic testing should be guided by the initial history, physical exam, and ECG and should focus on suspected underlying conditions. For example, echocardiogram testing is reasonable if aortic stenosis is suspected after the initial evaluation.
• Exercise stress testing can be useful in selected patients who experience syncope during exertion (COR IIa). Stress testing may reveal a potential cause of exertional syncope, such as exercise-induced ischemia with associated heart block.
• Cardiac monitoring devices may be useful to evaluate selected patients with syncope of suspected arrhythmic etiology (COR IIa). Multiple monitoring technologies are available (eg, Holter monitor, external loop recorder, patch recorders). The optimal approach is dependent on factors such as frequency of syncopal events, suddenness of incapacitation, and patient compliance.
• Continuous ECG monitoring is useful for admitted patients with suspected cardiac etiology (COR I). Inpatient telemetry may reveal an arrhythmic cause of syncope in intermediate- to high-risk patients.

In summary, the only “routine” tests for the evaluation of syncope include a careful history, physical exam, and 12-lead ECG. All subsequent testing and disposition decisions should be applied in a selective fashion, based on the initial evaluation.

Reference

1. Shen WK, Sheldon RS, Benditt DG, et al. 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2017;70(5):e39-e110.

Dr. Sun is associate professor in the department of emergency medicine at Oregon Health & Science University in Portland.