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August 1, 2017 Circulation. 2017;136:e60–e122. DOI: 10.1161/CIR.0000000000000499 e68

Recommendation for History and Physical Examination

COR LOE Recommendation

I B-NR A detailed history and physical examination should be performed in patients with syncope.58–66

See Online Data Supplement 1. The history should aim to identify the prognosis, diagnosis, reversible or ameliorable factors, comorbidities, medication use, and patient and family needs. Cardiac syncope carries a significantly worse prognosis than does neurally mediated syncope. Prognostic factors generally separate neurally mediated from cardiac syncope and are described in Section 2.3.3. The diagnostic history focuses on the situations in which syncope occurs, prodromal symptoms that provide physiological insight, patient’s self-report, bystander observations of the event and vital signs, and post-event symptoms. Video recordings are helpful when available. Time relationship to meals and physical activities and duration of the prodrome are helpful in differentiating neurally mediated syncope from cardiac syncope. Comorbidities and medication use are particularly important factors in older patients. A history of past medical conditions should be obtained, particularly with regard to the existence of preexisting cardiovascular disease.58–66 A family history should be obtained, with particular emphasis on histories of syncope or sudden unexplained death (or drowning). Historical characteristics associated with, though not diagnostic of, cardiac and noncardiac syncope are summarized in Table 4.

The physical examination should include determination of orthostatic blood pressure and heart rate changes in lying and sitting positions, on immediate standing, and after 3 minutes of upright posture.31 Careful attention should be paid to heart rate and rhythm, as well the presence of murmurs, gallops, or rubs that would indicate the presence of structural heart disease. A basic neurological examination should be performed, looking for focal defects or other abnormalities that would suggest need for further neurological evaluation or referral.

2.3.1 History and Physical Examination: Recommendation

Recommendation for Electrocardiography

COR LOE Recommendation

I B-NR In the initial evaluation of patients with syncope, a resting 12-lead electrocardiogram (ECG) is useful.76

See Online Data Supplement 2. ECG is widely available and inexpensive and can provide information about the potential and specific cause of the syncope episode (eg, bradyarrhythmia with sinus pauses or high-grade conduction block; ventricular tachyarrhythmia). It may demonstrate an underlying arrhythmogenic substrate for syncope or SCD. Subsets of patients with Wolff-Parkinson-White syndrome, Brugada syndrome, long-QT syndrome (LQTS), hypertrophic cardiomyopathy (HCM), or arrhythmogenic right ventricular cardiomyopathy (ARVC) have characteristic ECG features, which can prompt the decision to pursue further evaluation.

Despite the benefit of identifying a likely cause or potential clue about the cause of syncope from the ECG, prospective studies did not conclude that ECG findings significantly affected subsequent management.73,77–80 The prognostic value of an abnormal ECG in patients with syncope has been questioned, as well.69,81 However, a multicenter, prospective, observational study76 concluded that the presence of AF, intraventricular conduction disturbances, voltage criteria for left ventricular (LV) hypertrophy, and ventricular pacing were associated with increased risk of death from all causes at 1 year.

2.3.2 Electrocardiography: Recommendation

2.3.3 Risk Assessment: Recommendations

Syncope is a symptom that can be due to various causes, ranging from benign to life-threatening conditions. Risk stratification during initial evaluation is important for guiding the treatment and preventing long-term morbidity and mortality. However, risk stratification schemes for short- and long-term clinical outcomes are limited by the inclusion of all patients with syncope, without regard to the presence or absence of underlying medical conditions associated with syncope. For ex- ample, outcomes would not be expected to be similar for patients with vasovagal syncope (V VS), heart block with preserved ejection fraction, advanced cardiomyopathy and HF, acute gastric bleeding, or aortic dissection. The short-term prognosis of patients presenting with syncope is mainly related to the cause of syncope and the acute reversibility of the underlying condition; longterm prognosis is related to the effectiveness of therapy and the severity and progression of underlying diseases, especially cardiac or terminal illnesses.

Recommendations for Risk Assessment

COR LOE Recommendations

I B-NR Evaluation of the cause and assessment for the short- and long-term morbidity and mortality risk of syncope are recommended (Table 5).68,82,83,100

See Online Data Supplements 3 and 4. Syncope may be an acute result of major hemodynamic abnormalities or a manifestation of serious underlying disease. Thus, assessment of the cause of syncope and underlying comorbidities is necessary.

Short-term adverse events and deaths are determined largely by the cause of syncope and the effectiveness of the treatment. In patients without a presumptive cause of syncope, risk stratification for potential short-term outcomes is necessary for immediate decision making in the acute setting. Potential predictors of increased short-term risk of death and serious outcomes are listed in Table 5. Long-term adverse events and deaths are more likely determined by the underlying medical comorbidities, many of which are cardiac. The evaluation of patients with syncope should include a full assessment of the long-term risk factors, including those listed in Table 5.69,70,72–74,84–93,95,97

IIb B-NR Use of risk stratification scores may be reasonable in the management of patients with syncope.67,68,72,73,75,87,89,100,101

See Online Data Supplements 3 and 4. Investigators have reported numerous risk scores to predict adverse outcomes after syncope (examples in Table 6). This literature has important limitations, including inconsistent definitions of syncope, outcomes, outcome time frames, and predictors; inclusion of patients with serious outcomes already identified in the ED, which biases risk scores toward identifying “obvious” events; the use of composite outcomes that combine events with different pathophysiologies; small samples that limited model reliability; and limited external validation. Risk scores have not performed better than unstructured clinical judgment.64,67–75,96,98

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