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Summary

Background: there is huge variation in practice regarding syncope-related medical decision-making; external validation of clinical-decision rules has not been performed or has failed; abnormal electrocardiography (ECG) is typically included in studies; factors for abnormal ECG often include, eg, age, blood pressure, history of heart failure, brain natriuretic peptide (BNP), troponin; a 3-step approach to syncope can be helpful

Syncope vs seizure vs mechanical fall (Step 1): according to the literature, a few things help differentiate between seizure and syncope; postictal confusion is classic for seizure and should not happen with syncope; lateral tongue biting, especially bilateral, is very uncommon with syncope and common with seizure; urinary or fecal incontinence and shaking can occur with syncope or seizure; an appropriate story can identify a mechanical fall with no reason to suspect syncope; can be difficult to differentiate confusion or amnesia after an episode from syncope; the emergency medicine doctor's responsibility is to rule out anything dangerous; if differentiation between, eg, mechanical fall and syncope cannot be made, then work up the patient from all perspectives and make the decision to send them home or admit them

True syncope vs symptom syncope (Step 2): true syncope is asymptomatic, may or may not have a prodrome (eg, lightheadedness, dizziness, nausea), and there may be a brief episode of loss of consciousness with loss of postural tone, followed by a return to asymptomatic baseline; symptom syncope has an underlying cause (eg, pulmonary embolism [PE], gastrointestinal bleed) with the high-risk feature of syncope; history and physical examination are crucial for differentiating symptom syncope from true syncope; 2017 American College of Cardiology/American Heart Association/Heart Rhythm Society guidelines for the evaluation and management of patients with syncope recommends performing a detailed history and physical examination

Challenges in differentiating true vs symptom syncope: difficult to differentiate arrhythmia from another medical emergency in patients who experience syncope using an algorithm (eg, prospective assessment of all patients coming into the ED with syncope using such tools as statistics and regression analysis to identify key factors predicting bad outcomes); Pulmonary Embolism in Syncope Italian Trial (PESIT) study did not differentiate true syncope in patients vs symptom syncope; 17% to 20% of their patients had PE; high proportion of included patients found to have tachycardia, tachypnea, deep vein thrombosis and other clinical conditions; this is not a typical population seen with admission to the ED for syncope alone; other studies have followed up on patients admitted to the ED for syncope alone; PE found at a rate of 1% to 2% in those patients

Risk for arrhythmia in patients with true syncope (Step 3): speaker identifies 6 high-risk features (FAHEHE) for arrhythmia in patients with syncope

Family history: family history of sudden cardiac death at a young age or death at a young age from an unknown cause; plays an important role; if a young patient experiences syncope, family history must be obtained

Age: some clinical-decision rules require admission for patients >65 yr of age that syncopize; American College of Emergency Physicians guidelines — these state that different studies employ different ages as a decision-making threshold; age is likely a continuous variable affecting cardiovascular health rather than an arbitrary value; likelihood of arrhythmia increases with increasing age, but there is no age limit that precludes a patient from being considered low risk; anecdotal evidence — in patients <45 yr of age without any significant family history, the chance of having syncope related to an arrhythmia is incredibly low; the 65-yr-old-cutoff is not entirely evidence based

History, heart, or heart history: according to studies, history of congestive heart failure, coronary artery disease, myocardial infarction (MI), or structural heart disease are associated with high risk for arrhythmia contributing to syncope

Exertion: speaker admits any syncope associated with exertion for telemetry monitoring; exertion results in sympathetic surge that causes the heart to beat quickly and might predispose toward arrhythmia; the underlying issue does not resolve when exertion ceases

Hypotension: if hypotension persists after a syncopal episode, the patient should be admitted and observed under telemetry monitoring

Abnormal ECG: non-sinus rhythm — any atrioventricular (AV) block increases risk; many people suffer from first-degree AV block; does not necessarily require admission per speaker, but some papers disagree; second- or third-degree AV block requires admission; evidence of ventricular tachycardia or ventricular fibrillation requires admission; consider admission for atrial fibrillation of flutter; higher incidences of premature ventricular contractions (PVCs) and premature atrial contractions (PACs) can be considered for admission, but there is no hard number to use as a threshold; ventricular bigeminy or a PVC after every QRS are indications for admission

Intervals on abnormal ECG: patients with prolonged QTc and widened QRS should be admitted; left bundle or right bundle branch block should be admitted for syncope; admit any left anterior fascicular block or left posterior fascicular block; admit for bifascicular block (eg, right bundle branch block plus a first-degree AV block, right bundle plus a left anterior or left posterior block, left anterior plus left posterior block plus first-degree AV block) or trifascicular block; trifascicular block can lead to complete heart block at any time; possibility of complete heart block with symptomatic trifascicular block should be assumed, so a higher level of care is required; for asymptomatic trifascicular block, only urgent outpatient care and cardiology follow-up are required

Evidence for ischemia on abnormal ECG: ST changes (eg, ST depressions) and Q waves; patient with a Q wave indicating an old ischemia may require admission because it provides evidence of a heart attack;

Syncope syndromes on abnormal ECG: Wolff-Parkinson-White (WPW) syndrome, hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular dysplasia or Brugada syndrome on ECG require admission and may require a higher level of care; WPW syndrome includes a short PR interval, slurred upslope on R wave (ie, Delta wave); with HCM, big or deep Q waves (“dagger Qs”) are seen; arrhythmogenic right ventricular dysplasia shows Epsilon wave; Brugada syndrome shows shark fin-like or saddleback deformity

Canadian syncope risk tool: validated in a JAMAInternal Medicine paper; included only patients presenting to the ED with syncope who had no known reason for syncope by the end of the ED visit (ie, true syncope); patients who presented with symptom syncope were not included; points (possibly negative points) are assigned for previous history of heart disease (a predisposition toward vasovagal syncope), systolic blood pressure <90 mm Hg or >180 mm Hg, elevated troponin level, abnormal QRS axis, prolonged QRS interval >130 ms, QT interval >480 ms, a diagnosis per the ED doctor of vasovagal syncope, or diagnosis of cardiac syncope; this resulted in a linear correlation; lower score was associated with lower risk, and higher score with higher risk; this tool is the only syncope decision tool that has passed external validation

Diagnosis: obtain troponin levels if the Canadian syncope risk tool is used; every patient who presents to the ED with syncope should have ECG; head computed tomography is not required unless the patient has other evidence or signs and symptoms of head trauma; no strict criteria for which patients with syncope require laboratory tests; speaker’s practice (no evidence to support) is to obtain laboratory tests, including troponin, for patients aged >45 yr; in syncope numerous studies have found higher troponin level increases the risk for a problem in the short term

The FAINT syncope score: this was presented in the Annals of Emergency Medicine; it was an attempt to develop a clinical decision-making rule; ECG and laboratory tests obtained from patients aged >60 yr; endpoints death and adverse outcomes at 30 days; this includes failure (1 point), arrhythmia history (1 point), initial abnormal ECG result (1 point), elevated N-terminal prohormone of BNP (2 points), and elevated troponin (1 point); a score of 0 indicates very low risk; a score of 1, 2, or 3 might indicate a risk level too high to send the patient home