Electrophysiologic evaluation and outcome of patients with syncope of unknown origin

Electrophysiologic studies were performed in 134 patients (87 males, mean age 59 years) with unexplained syncope. Seventy-one patients had organic heart disease (ischaemic in 50). Electrophysiologic studies revealed conduction abnor-malities and tachy arrhythmias that couldaccountfor syncope in 40 patients (30%). Thirty-seven (93%) of these patients received pacing or antiarrhythmic therapy compared with 23 (24%) of the remaining 94 patients who had a negative study and received empiric therapy (P < 0-0001). Risk of having an abnormal electrophysiologic study was greater in patients with underlying heart disease (P<0-05). During a mean follow-up of 22±17 months, 26 patients (19%) either had recurrent syncope (22 patients) or died (four patients) suddenly. Men had a higher incidence of recurrent syncope than women (26 % vs6%, P<0-005). Other clinical characteristics, electrophysiologic findings, final diagnosis and therapy at discharge were not predictive of outcome. We conclude that (1) 19 % of patients investigated for syncope will have a recurrent event, (2) female gender may be an independent predictor of favourable outcome