Recurrent, sudden temporary
loss of consciousness is a common clinical problem: in the absence of electrocardiographic monitoring during a
syncopal episode (S), abnormalities demonstrated by an electrophysiological study (ES) may suggest the etiology of S. We have performed a complete ES in 53 Pts (M. 38-F. 15, mean age 63 y.) with recurrent unexplained S (3.8 S/pt) by means of a standardized protocol. Group I: 30 Pts (mean age 65 y, 3.6 S/pt) with structural
heart disease. Thirteen of these had abnormal ES findings: inducible
ventricular tachycardia in 6, prolonged HV interval in 7 (with
bundle branch block), very fast
atrial flutter in one. Group II: 23 Pts (mean age 61 y., 3, 9 S/pt), without organic
heart disease. The ES was abnormal in 14 Pts showing a prolonged HV interval in 11 (with
bundle branch block), an intrahisian block in 1 and an inducible AV nodal
tachycardia with heart rate greater than 200/m' in one. Only the Pts with abnormal ES were treated according to their condition with
amiodarone or with an implantable pacemaker. Three PTs with C.H.D. and normal ES successfully underwent by-pass surgery. During the follow-up (20 months)
therapy based on ES provided symptomatic relief (no S) in 25 of 26 Pts with abnormal electrophysiological study.
Syncope persisted in 4 of 26 Pts in whom ES did not define a mechanism of S. No
sudden death in any Pt.
CONCLUSIONS: ES was, therefore, of diagnostic value in more than half of the patients with
syncope of unknown cause and long-term treatment based on ES was successful in the prevention of S (remission rate of 93% in patients treated with
amiodarone or pacemaker).