Is Syncope from a Cardiac Cause?

Syncope most often is due to benign etiologies (e.g., reflex syncope, orthostatic hypotension), but a substantial minority of patients (≈15%) have higher-risk cardiac etiologies (e.g., arrhythmia, aortic stenosis, ischemia). In this systematic review of 11 studies (≈4300 patients), researchers evaluated the accuracy of the initial clinical evaluation for patients with syncope.

Predictors associated with substantially higher risk for cardiac syncope were age at first syncope ≥35 (likelihood ratio, 3.3), history of atrial fibrillation or flutter (LR, 7.3) or severe structural heart disease (LR, 4), and cyanosis witnessed during the syncopal episode (LR, 6.2). Cardiac biomarkers (e.g., troponin, B-type natriuretic peptide) might have diagnostic…