Clinical electrophysiology study in patients with syncope of undetermined etiology

The periodicity of symptoms in patients who present with syncope restricts the diagnostic value of prolonged electrocardiographic monitoring and furthermore, demonstration of arrhythmias in the absence of symptoms may not enable a firm diagnosis. Because of this, electrophysiology study is often necessary. A series of 89 consecutive patients with syncope of unknown origin is reported, highlighting the value and limitations of this technique. A diagnostic yield of 35% was found, with the majority having abnormalities of atrioventricular conduction. The presence of organic heart disease, 12-lead electrocardiographic abnormalities and a number of syncopal episodes did not influence the diagnostic utility of electrophysiology study. Patient follow-up suggested that therapeutic decisions based on the findings of electrophysiology study provide satisfactory symptomatic relief in a high percentage of cases, with a recurrence rate of 25% at mean follow-up of 14 months.