[Natural history of syncope of undetermined origin with inconclusive electrophysiologic examination]

Between 1985 and 1986, 109 consecutive patients with unexplained syncope after clinical and standard electrocardiographic examination underwent electrophysiological investigation. In 61 cases (56%), 35 men and 26 women (mean age 69 +/- 13 years) no firm diagnosis could be made. These patients were the study group. Underlying cardiac disease was present in 23%, coronary artery disease in 10% of cases. In 33 cases, the basal ECG was normal (54%). Sixty patients (one lost to follow-up) were studied over an average of 38 +/- 12 months. Global mortality and recurrence rate were 13 and 18% respectively. There were no sudden deaths in the 8 fatalities. The mechanism of the 17 recurrent syncopes was cardiac in 5 cases, vasovagal in 1 case, uncertain in 11 cases. Of the 5 cardiac syncopes, 3 were related to 3rd degree atrioventricular block occurring 7 to 49 months after the initial electrophysiological investigation. No predictive criteria of recurrence could be identified. Empiric treatment proposed to 28% of patients did not prevent recurrent syncope and did not improve global survival. Inconclusive electrophysiological investigation of patients with unexplained syncope defines a population with a low risk of sudden death. Recurrent syncope is common. The recurrence of symptoms is an indication to repeat the aetiological investigations which should include a tilt-test ot another electrophysiological investigation. Empiric treatment has not been shown to be effective.