Syncope: Evaluation and Differential Diagnosis

 

Am Fam Physician. 2017 Mar 1;95(5):303-312B.

  Patient information: See related handout on fainting.

Author disclosure: No relevant financial affiliations.

Syncope is an abrupt and transient loss of consciousness caused by cerebral hypoperfusion. It accounts for 1% to 1.5% of emergency department visits, resulting in high hospital admission rates and significant medical costs. Syncope is classified as neurally mediated, cardiac, and orthostatic hypotension. Neurally mediated syncope is the most common type and has a benign course, whereas cardiac syncope is associated with increased morbidity and mortality. Patients with presyncope have similar prognoses to those with syncope and should undergo a similar evaluation. A standardized approach to syncope evaluation reduces hospital admissions and medical costs, and increases diagnostic accuracy. The initial assessment for all patients presenting with syncope includes a detailed history, physical examination, and electrocardiography. The initial evaluation may diagnose up to 50% of patients and allows immediate short-term risk stratification. Laboratory testing and neuroimaging have a low diagnostic yield and should be ordered only if clinically indicated. Several comparable clinical decision rules can be used to assess the short-term risk of death and the need for hospital admission. Low-risk patients with a single episode of syncope can often be reassured with no further investigation. High-risk patients with cardiovascular or structural heart disease, history concerning for arrhythmia, abnormal electrocardiographic findings, or severe comorbidities should be admitted to the hospital for further evaluation. In cases of unexplained syncope, provocative testing and prolonged electrocardiographic monitoring strategies can be diagnostic. The treatment of neurally mediated and orthostatic hypotension syncope is largely supportive, although severe cases may require pharmacotherapy. Cardiac syncope may require cardiac device placement or ablation.

Syncope is a sudden, brief, and transient loss of consciousness caused by cerebral hypoperfusion.1 Other nontraumatic loss of consciousness syndromes include seizures, cataplexy, metabolic disorders, acute intoxications, vertebrobasilar insufficiency, transient ischemic attack, cerebrovascular accident, and psychogenic pseudosyncope.2,3

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SORT: KEY RECOMMENDATIONS FOR PRACTICE

Clinical recommendationEvidence ratingReferences

Patients who present with presyncope should be evaluated similarly to those who present with syncope.

C

20, 21

Patients with syncope and evidence of congestive heart failure or structural heart disease, abnormal electrocardiographic findings, or a family history of sudden death should be admitted to the hospital for emergent evaluation.

C

1, 25, 27, 29

Patients presenting with syncope should have orthostatic blood pressure measurements and standard 12-lead electrocardiography.

C

1, 2, 25, 27, 29

Laboratory and imaging studies should be ordered for patients with syncope only if clinically indicated by the history and physical examination.

C

1, 27, 39, 40, 42, 43, 50, 51

Implantable loop recorders increase diagnostic yield, reduce time to diagnosis, and are cost-effective for suspected cardiac syncope and unexplained syncope.

C

1, 39, 4448

Patients with syncope who are at low risk of adverse events (e.g., those with symptoms consistent with vasovagal or orthostatic hypotension syncope, no history of heart disease, no family history of sudden cardiac death, and normal electrocardiographic findings) may be safely followed without further intervention or treatment.

C

1, 25, 27, 29


A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, go to http://www.aafp.org/afpsort.

SORT: KEY RECOMMENDATIONS FOR PRACTICE

Clinical recommendationEvidence ratingReferences

Patients who present with presyncope should be evaluated similarly to those who present with syncope.

C

20, 21

Patients with syncope and evidence of congestive heart failure or structural heart disease, abnormal electrocardiographic findings, or a family history of sudden death should be admitted to the hospital for emergent evaluation.

C

1, 25, 27, 29

Patients presenting with syncope should have orthostatic blood pressure measurements and standard 12-lead electrocardiography.

C

1, 2, 25, 27, 29

Laboratory and imaging studies should be ordered for patients with syncope only if clinically indicated by the history and physical examination.

C

1, 27, 39, 40, 42, 43, 50, 51

Implantable loop recorders increase diagnostic yield, reduce time to diagnosis, and are cost-effective for suspected cardiac syncope and unexplained syncope.

C

1, 39, 4448

Patients with syncope who are at low risk of adverse events (e.g., those with symptoms consistent with vasovagal or orthostatic hypotension syncope, no history of heart disease, no family history of sudden

The Authors

show all author info

LLOYD A. RUNSER, MD, MPH, FAAFP, is associate program director and research coordinator at the Womack Army Medical Center Family Medicine Residency Program, Fort Bragg, N.C., and assistant professor in the Department of Family Medicine at the Uniformed Services University of the Health Sciences, Bethesda, Md....

ROBERT L. GAUER, MD, is assistant professor of family medicine at the Uniformed Services University of the Health Sciences and a hospitalist at Womack Army Medical Center.

ALEX HOUSER, DO, is a second-year resident at the Womack Army Medical Center Family Medicine Residency Program.

Address correspondence to Lloyd A. Runser, MD, MPH, at lloyd.a.runser2.mil@mail.mil. Reprints are not available from the authors.

Author disclosure: No relevant financial affiliations.

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