Syncope. Identifying cardiac causes in older patients.

Syncope is a transient loss of consciousness and postural tone, with spontaneous recovery, and may represent an episode of aborted cardiac arrest. The final common pathway for loss of consciousness from non-neurologic causes is hypoperfusion of the reticular activating system. The etiology of syncope in older patients frequently includes a myriad of causes (e.g., orthostatic hypotension, medication side effects, sick sinus syndrome, atrioventricular block, carotid hypersensitivity, ventricular tachycardia, and aortic stenosis). Initial evaluation must include a detailed history, complete physical examination, and 12-lead ECG, which provides a framework as to the probable cause of syncope in approximately 40% of patients. Echocardiography, electrophysiology testing, and head-upright tilt table testing will confirm the diagnosis in most of the remainder. Approximately 25% of patients will have no identifiable cause of syncope, but have a better prognosis than patients with a confirmed cardiac cause of syncope. Treatment is directed at the underlying cause.