The emergency department approach to syncope: evidence-based guidelines and prediction rules.

Syncope is a sudden, transient loss of consciousness associated with inability to maintain postural tone followed by spontaneous recovery and return to baseline neurologic status. Global cerebral hypoperfusion is the final pathway common to all presentations of syncope, but this symptom presentation has a broad differential diagnosis. It is important to identify patients whose syncope is a symptom of a potentially life-threatening condition. This article reviews the current status of syncope from the emergency department perspective, focusing on the current evidence behind the various clinical decision rules derived during the past decade.