Syncope is a common occurrence in the emergency department, accounting for approximately 1% to 3% of presentations. Syncope is best defined as a brief loss of consciousness and postural tone followed by spontaneous and complete recovery. The spectrum of etiologies ranges from benign to life threatening, and a structured approach to evaluating these patients is key to providing care that is thorough, yet cost-effective. This issue reviews the most relevant evidence for managing and risk stratifying the syncope patient, beginning with a focused history, physical examination, electrocardiogram, and tailored diagnostic testing. Several risk stratification decision rules are compared for performance in various scenarios, including how age and associated comorbidities may predict short-term and long-term adverse events. An algorithm for structured, evidence-based care of the syncope patient is included to ensure that patients requiring hospitalization are managed appropriately and those with benign causes are discharged safely.
It is a busy day in your ED when 3 patients arrive within minutes of each other. A 51-year-old woman arrives by EMS. She felt faint while riding her racing bicycle and got off just before losing consciousness. EMS found her conscious, but pale, with heart rate, 50 beats/min; blood pressure, 90/50 mm Hg; respiratory rate, 25 breaths/min; and oxygen saturation, 98% on room air. EMS provided 1 liter of normal saline without a change in her vital signs. In the ED, her BP is still 90/60 mm Hg. She tells you that just before she got off her bike, she experienced pain in her throat, but she denies chest pain, shortness of breath, or headache. She appears uncomfortable and complains of persisting throat pain and states she is afraid of dying. Her initial ECG shows a sinus bradycardia but is otherwise normal. Her past medical history is not significant. She takes no medications. She is an experienced marathon runner and has never had similar complaints. You wonder what could have caused the syncope and persistent bradycardia.
A short time later, a 19-year-old woman presents to the ED after fainting in the park while attending a party. She tells you she suddenly felt light-headed, warm, and sweaty, and then passed out. According to her friends, she had a brief period of her arms jerking. When she came to, she felt very tired. Her vital signs are: respiratory rate, 18 breaths/min; oxygen saturation, 99% on room air; heart rate, 85 beats/min; blood pressure, 110/70 mm Hg; and temperature, 36.6oC. There is no evidence of tongue biting, and her neurologic examination is normal. Though she says she does not believe she is pregnant, you perform an hCG test, which is negative. You wonder about the significance of her arm jerking and whether she might have had a seizure.
In the next room is a 77-year-old man brought in by his daughter-in-law. He had a brief loss of consciousness, without sustaining an injury, and is now fully recovered, feels fine, and states he wants to leave. His daughter-inlaw, however, does not want to take him home “like this.” His vital signs are: respiratory rate, 16 breaths/min; oxygen saturation, 96% on room air; heart rate, 75 beats/ min; blood pressure, 150/90 mm Hg; and temperature 37.2oC. His ECG shows a left bundle branch block that is unchanged compared with his old ECG. His past medical history is significant for an acute myocardial infarction, a CABG, hypertension, and diabetes. His medications include a diuretic, aspirin, metoprolol, an ACE inhibitor, and metformin. His bedside glucose is within normal limits.
He looks so well that you are tempted to follow his wishes and send him home, but something just doesn’t seem right...
Syncope is a temporary loss of consciousness and posture, often described as "fainting" or "passing out." Near-syncope is defined as a patient almost losing consciousness, and it is approached in the same way as syncope. A 2012 prospective cohort study comparing 244 patients with near-syncope and 293 with syncope showed that patients with near-syncope are as likely as those with syncope to experience critical interventions or adverse events. However, patients with near-syncope were less likely to be hospitalized, 49% versus 69% respectively, which may be a potential risk-management issue.1
Syncope accounts for 1% to 3% of all emergency department (ED) visits.2-7 The incidence of syncope in the ED increases with age, with a sharp rise in patients older than 70 years.8,9 The overall incidence of syncope is 2.6 per 1000 person-years, with an incidence of 1.6 per 1000 person-years for the first episode.8 Syncope is reported as the primary presenting complaint in 75% of syncope patients seen in the ED, and, in 45%, it was the only complaint.6
Patients presenting to the ED likely represent a different population from those seen in other clinical settings, with a higher pretest probability for significant underlying etiology.10,11 In the Framingham study, the incidence for the first syncope in the general population was 6.2 per 1000 person-years, with only 56% of patients reporting having consulted a physician for evaluation.9
Syncope is a symptom with a wide range of possible underlying causes. The most effective diagnostic tools in evaluating a patient with syncope are history, physical examination, and electrocardiogram (ECG).8,12-15 Multiple studies in Europe and North America have shown that unstructured evaluations for syncope result in high costs and low diagnostic yield when compared to evaluations that follow a standardized protocol.2-4,7,13,16-23 The use of algorithms, guided by clinical findings, resulted in a reduction of undiagnosed cases from 50%-70% down to 17%-25%.4,7,8-12-14,17,21,24-39
This issue of Emergency Medicine Practice presents the best available evidence for the diagnostic strategy and risk stratification of patients with syncope presenting to the ED and provides guidance for differentiating patients who can be safely discharged from those who are at risk for an adverse outcome and need to be hospitalized.
A literature search from 1945 through January 2014 was performed using Ovid MEDLINE®, Embase, and the Cochrane Database of Systematic Reviews. Search terms included syncope, transient loss of consciousness, collapse, risk stratification, emergency department, and synonyms. The National Guideline Clearinghouse (www.guideline.gov) was searched with equivalent search terms for syncope management guidelines on risk stratification in the ED published in the last decade.
Clinical guidelines regarding the evaluation and diagnosis of syncope have been published by many organizations, including the American College of Emergency Physicians (ACEP), the European Society of Cardiology (ESC), the National Institute for Health and Care Excellence (NICE), and the Canadian Cardiovascular Society (CCS). (See Table 1.)
There were 1310 English language articles retrieved, selected, and graded using standardized grading forms by 2 independent reviewers. Inclusion criteria were risk stratification, management of syncope in the ED, risk factors of syncope, and articles most relevant to emergency medicine. Studies of populations hospitalized for syncope were included to draw a complete image of the etiology, diagnostic strategies, and outcomes. Case reports, letters, editorials, and nonsystematic reviews (expert opinion) were excluded. Systematic review and guideline references were checked for relevant articles missing in the search. A total of 172 articles were used as best available evidence for this issue.
Syncope and related conditions proved to be infrequently and inconsistently defined in the current medical literature.44 Some study populations included patients with seizures and hypoglycemia. The terms vasovagal, neurocardiogenic, neurogenic, and reflex syncope are inexactly defined in different papers but are generally synonymous. This article will use the term neurally mediated syncope.
The syncope literature consists mainly of prospective and retrospective cohort studies, case reports, nonsystematic reviews, and expert opinion. Most studies have small sample sizes and are thus assigned a low level of evidence.
Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.
To help the reader judge the strength of each reference, pertinent information about the study will be included in bold type following the reference, where available. In addition, the most informative references cited in this paper, as determined by the authors, will be noted by an asterisk (*) next to the number of the reference.
Suzanne Y. G. Peeters, MD; Amber E. Hoek, MD; Susan M. Mollink, MD; J. Stephen Huff, MD
April 2, 2014