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Circulation. 2017;136:e60–e122. DOI: 10.1161/CIR.0000000000000499 August 1, 2017 e69 CLINICAL STATEMENTS AND GUIDELINES

Although having precise definitions for high-, intermediate-, and low-risk patient groups after an episode of syncope would be useful for managing these patients, evidence from current clinical studies renders this proposal challenging because of a large number of confounders. Risk markers from history, physical examination, laboratory investigations, study endpoints, adverse event rates, and time intervals between these events are variable from study to study. Current data are best grouped into short-term risk (associated with outcomes in the ED and up to 30 days after syncope) and long-term risk (up to 12 months of follow-up). Risk markers are summarized in Table 5.64,67–70,72–75,82–98 The types of events, event rates, and study durations from investigations that estimated risk scores are summarized in Table 6.64,65,76,81,87,89,92,97,99 2.3.4. Disposition After Initial Evaluation: Recommendations The evaluating provider must decide whether further workup can continue in an outpatient setting or whether hospital-based evaluation is required. The purpose of hospital-based evaluation is to expedite the treatment of identified serious conditions or to continue the diagnostic evaluation in the absence of a presumptive cause of syncope.105,106 The disposition decision is complicated by varying resources available for immediate testing, a lack of consensus on acceptable short-term risk of serious outcomes, varying availability and expertise of outpatient diagnostic clinics, and the lack of data demonstrating that hospitalbased evaluation improves outcomes. In patients with a presumptive cause of reflex-mediated syncope and no other dangerous medical conditions identified, hospitalbased evaluation is unlikely to provide benefit.35 In patients with perceived higher risk, the healthcare provider may recommend a hospital-based evaluation. In this setting, a structured ED protocol can be effective as an alternative to inpatient admission.107–110

Decision support algorithms may reduce health service use in the evaluation of syncope (Figures  1 and 2),105,111–113 although there are currently insufficient data to advocate the use of specific decision support algorithms for making disposition decisions. Specialized syncope evaluation units may lead to reduced health service use and increased diagnostic rates.114–119 However, the logistical and financial feasibility of specialized syncope units in North American settings is unknown. A wider acceptance of syncope units requires further evidence of improvement in clinical outcomes. Individual risk factors (Table 5) and risk scores (Table  6) are correlated with short- and longterm clinical outcomes, but they are not primary determinants for admission to hospital. Presence of ≥1 serious medical condition, summarized in Table 7, is the key determinant for further in-hospital management of patients after syncope.90,98

Recommendations for Disposition After Initial Evaluation

COR LOE Recommendations

I B-NR Hospital evaluation and treatment are recommended for patients presenting with syncope who have a serious medical condition potentially relevant to the cause of syncope identified during initial evaluation.105,106,120

See Online Data Supplements 5 and 6. Table 7 provides examples of serious conditions associated with syncope that may require inpatient evaluation and “treatment.”

Arrhythmic causes may require consideration of pacemaker/implantable cardioverter-defibrillator (ICD) placement or revision and/or medication modification. Cardiac causes require treatment of the underlying condition (eg, medication management and consideration of surgical intervention for critical aortic stenosis). Finally, a large spectrum of noncardiac serious conditions may be associated with syncope and require management of the underlying problem (eg, severe anemia from a gastrointestinal bleed).

IIa C-LD It is reasonable to manage patients with presumptive reflex-mediated syncope in the outpatient setting in the absence of serious medical conditions.35

See Online Data Supplements 5 and 6. Patients with presumptive V VS have a long-term risk of death similar to that of risk-matched patients without syncope.35 Hospital-based evaluation for presumptive V VS is unlikely to improve long-term outcomes. Possible exceptions that might require hospital-based evaluation include frequent recurrent syncope with risk of injury or identified injury related to syncope.

IIa B-R In intermediate-risk patients with an unclear cause of syncope, use of a structured ED observation protocol can be effective in reducing hospital admission.107–110

See Online Data Supplements 5 and 6. Two small RCTs suggest that structured ED-based protocols, consisting of time-limited observation and expedited access to cardiac testing/consultation, result in reduced health service use without adverse impact on clinical outcomes when compared with unstructured hospital admission. “Intermediate” risk factors included the following: ≥50 years of age; prior history of cardiac disease, cardiac device without evidence of dysfunction, concerning ECG findings, or family history of early SCD; and symptoms not consistent with reflex-mediated syncope. Both trials also allowed unstructured physician judgment to identify intermediate-risk patients.107–110

IIb C-LD It may be reasonable to manage selected patients with suspected cardiac syncope in the outpatient setting in the absence of serious medical conditions.106,121–123

See Online Data Supplements 5 and 6. Hospital-based evaluation of syncope of unclear cause, in the absence of other serious identified medical conditions, has not demonstrated an improvement in patient-relevant outcomes. Several observational studies suggest modest diagnostic yield of hospital admission.121–123 Patients evaluated for suspected cardiac syncope in outpatient settings are seldom admitted for diagnostic purposes, and it may be reasonable to extend a similar approach to EDs after initial evaluation is completed in the ED. Primary providers can consider expedited referral to specialists with expertise in syncope, as indicated by availability of resources and provider’s assessment of short-term risk of serious outcomes, as an alternative to extended hospital-based evaluation.

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