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August 1, 2017 Circulation. 2017;136:e60–e122. DOI: 10.1161/CIR.0000000000000499 e70 3 ADDITIONAL EVALUATION AND DIAGNOSIS The selection of a given diagnostic test, after the initial history, physical examination, and baseline ECG, is a clinical decision based on the patient’s clinical presentation, risk stratification, and a clear understanding of diagnostic and prognostic value of any further testing. A broad-based use of additional testing is costly and often ineffective. This section provides recommendations for the most appropriate use of additional testing for syncope evaluation. See Figure 3 for the algorithm for additional evaluation and diagnosis for syncope. 3.1 Blood Testing: Recommendations The availability of simple and accurate biomarkers might streamline risk stratification and diagnosis of the cause of syncope. This section reviews circulating biomarkers, which are being evaluated as markers either of hypotension or underlying disease processes. None have met with strong success. Table 4. Historical Characteristics Associated with Increased Probability of Cardiac and Noncardiac Causes of Syncope60,67–75 More Often Associated With Cardiac Causes of Syncope Older age (>60 y) Male sex Presence of known ischemic heart disease, structural heart disease, previous arrhythmias, or reduced ventricular function Brief prodrome, such as palpitations, or sudden loss of consciousness without prodrome Syncope during exertion Syncope in the supine position Low number of syncope episodes (1 or 2) Abnormal cardiac examination Family history of inheritable conditions or premature SCD (<50 y of age) Presence of known congenital heart disease More Often Associated With Noncardiac Causes of Syncope Younger age No known cardiac disease Syncope only in the standing position Positional change from supine or sitting to standing Presence of prodrome: nausea, vomiting, feeling warmth Presence of specific triggers: dehydration, pain, distressful stimulus, medical environment Situational triggers: cough, laugh, micturition, defecation, deglutition Frequent recurrence and prolonged history of syncope with similar characteristics SCD indicates sudden cardiac death. Table 5. Short- and Long-Term Risk Factors* Short-Term Risk Factors (≤30 d) Long-Term Risk Factors (>30 d) History: Outpatient Clinic or ED Evaluation Male sex74,85,101,102 Male sex68,90 Older age (>60 y)88 Older age67,74,75,90 No prodrome68 Absence of nausea/vomiting preceding syncopal event93 Palpitations preceding loss of consciousness83 VA68,90 Exertional syncope83 Cancer68 Structural heart disease70,83,88,101,103 Structural heart disease68,103 HF74,83,85,88 HF90 Cerebrovascular disease70 Cerebrovascular disease68 Family history of SCD70 Diabetes mellitus104 Trauma68,101 High CHADS-2 score95 Physical Examination or Laboratory Investigation Evidence of bleeding83 Abnormal ECG84,90,93 Persistent abnormal vital signs70 Lower GFR Abnormal ECG68,72,74,75,105 Positive troponin75 *Definitions for clinical endpoints or serious outcomes vary by study. The specific endpoints for the individual studies in this table are defined in Online Data Supplements 3 and 4 and summarized in Table 6 for selected studies. This table includes individual risk predictors from history, physical examination, and laboratory studies associated with adverse outcomes from selected studies. CHADS-2 indicates congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, and stroke or transient ischemic attack; ECG, electrocardiogram; ED, emergency department; GFR, glomerular filtration rate; HF, heart failure; SCD, sudden cardiac death; and VA, ventricular arrhythmias. Recommendations for Blood Testing COR LOE Recommendations IIa B-NR Targeted blood tests are reasonable in the evaluation of selected patients with syncope identified on the basis of clinical assessment from history, physical examination, and ECG.124 See Online Data Supplements 7 and 8. Although broad-panel testing is common in clinical practice at the point of triage, there are no data on the utility of this approach. Data to support specific blood testing are largely descriptive data from case series and registries. Complete blood count and electrolyte panel are frequently obtained during syncope evaluation. The diagnostic yield is low when these are used routinely; however, when these blood tests are conducted in patients with a suspected related diagnosis (eg, history of peptic ulcer disease, or tarry stools associated with OH on physical examination), test results can be diagnostic and useful for guiding therapy. Thus, specific testing should stem from the assessment by history and physical examination when the nature of the syncope presentation or associated comorbidities suggests a diagnostic or more likely prognostic role for laboratory testing. Results have not been linked to clinical decision making or outcomes.125–128 Downloaded from http://ahajournals.org by on October 7, 2026