A01-1 Adenosine-induced syncope: Prevalence and characteristics

Abstract

Introduction: Occurrence of ventricular pause of more than 6 seconds following administration of 20 mg b&s of intravenous adenosine (ATP test) has been observed in a relatively high percentage of patients (pts) with unexplained syncope. However, these results have been reported in a relatively limited number of pts in only 2 series. The aim of OUT study was to assess the prevalence of this entity and pts' characteristics with positive ATP test in a larger single-center study.Methods: Pts were recruited consecutively based on following criteria: 1) at least one syncopal episode defined according to ESC guidelines, 2) no diagnosis after the usual work up, including systematically: clinical evaluation, orthostatic hypotension, ECG and when necessary, carotid sinus massage, electrophysiological study, and tilt table test. ECG was continuously monitored during and after ATP test and a ventricular pause longer than 6 seconds was considered as abnormal.Results: Among the 109 pts with unexplained syncope after a complete evaluation, 7 had a positive ATP test (6.4%). When compared to negative ATP group, pts with positive ATP test had the following characteristics: female predominance (85.7% vs 49.5%, p=O.OQ signiiicmtly older age (75.4&11X vs 56.1&17.8 years, p<O.O06), more syncopal episodes during life (6.14 vs 4.54, p=NS), older age at the first episode (63.6 vs 47.4 years, p=O.O5). Prodromal symptoms and traumatic consequences of the syncape were not signiiicantly different between the 2 groups. Conclusion: Although rare, ATP-induced syncope accounts for 6% of pts with unexplained syncope after a complete evaluation. Women older than 70 years represent the population in whom the ATP test had the highest likelihood of being positive. The treatment by pacemaker remains to be evaluated.