Cardiac electrophysiological assessment and the natural history of unexplained syncope
Crozier, I.G.; Low, C.J.; Dow, L.J.; Ikram, H.
New Zealand Medical Journal 101(841): 106-108
1988
ISSN/ISBN: 0028-8446 PMID: 3380445 Document Number: 313587
There is little data on cardiac electrophysiological assessment and long term follow-up of unexplained syncope from Australasia. We present 94 patients with unexplained syncope who underwent such assessment and follow-up for an average of 52 months in 92 patients. Of the 94 investigated 57 were male, the average age was 61 years and average number of syncopal episodes prior to study was 8 (minimum 2). Forty-two patients had heart disease. Patients were divided into 3 groups on results of electro physiological testing. Normal (31 patients), group 1 with intermediate abnormalities of sinus node function or atrioventricular conduction (37 patients) and group 2 in whom the abnormalities were felt likely to represent the cause of syncope (26 patients). Abnormalities detected in group 2 were sinus node dysfunction in 12, abnormal atrioventricular nodal conduction in 8, abnormal infranodal conduction in 2, vagal hypersensitivity in 3 and ventricular tachycardia in two. Follow-up for a mean of 52 months was obtained in 92 patients. Recurrent syncope occurred in 37% of the patients. Treatment reduced recurrent syncope to a level approaching statistical significance in group 2 patients (50% to 13%; 0.01 > p > 0.05) but had little influence on recurrent syncope in group 1 or normal patients. There were 14 deaths over the follow-up period. Mortality was predicted by group 2 electrophysiological abnormality (p < 0.02) and the presence of heart disease (p < 0.05) and was not reduced by specific therapy. Sudden death occurred in 3 patients, all with heart disease. We conclude that electrophysiologic assessment has a role in the evaluation of unexplained syncope, but that many minor abnormalities are of low specificity in prediciting the response to therapy. There is a high spontaneous remission rate in all patient groups and patients without heart disease do not have an excess mortality.