Syncope of Unknown Origin: First Head-Up Tilt Test or Electrophysiologic Study?

Syncope is a nonspecific symptom of a wide variety of disorders. It is defined as the temporary loss of consciousness and postural tone, followed by spontaneous recovery without resuscitative measures. It is diagnosed in about 3% of the patients seen in the emergency room and in about 1% of the patients admitted to a hospital (1, 2). Syncope can be classified as cardiovascular, noncardiovascular, and unexplained.