0164: Evolution of preexcitation syndrome in children

Previous studies reported a spontaneous disappearance of preexcitation syndrome (PS) in patients with a long accessory pathway (AP) effective refractory period (ERP) and in children 12 y with inducible SVT and short AP-ERP. The purpose of the study was to collect the data of untreated children with a PS, studied 2 times at least one year of interval. Methods 2 baseline electrophysiological studies (EPS) were performed within 1 to 25 years of one another (mean 6±years) in 39 children and teenagers, 17 boys, 22 girls, aged initially from 1 to 19 years (12.5±4), with overt PS. First EPS (EPS1) was indicated for syncope (n=4), atrioventricular reentrant tachycardias (AVRT)(n=17) or for asymptomatic PS (n=18). The protocol was similar, performed in control state (CS) and after isoproterenol. Results At EPS2, among patients studied for syncope at EPS1, 1 has still syncope, 2 have AVRT, 1 is asymptomatic. Among patients with AVRT at EPS1, 14 (82%) have still AVRT, 3 are asymptomatic. Among asymptomatic patients, 13 (72%) remain asymptomatic, 2 have AVRT, 3 have syncope. AVRT in children presenting initially with syncope or initially asymptomatic children occurred in 2/4 with inducible AVRT at EPS1. The higher rate conducted by AP was similar in CS and after isoproterenol at EPS2 (178±72bpm, 203±81) and at EPS1 (188±62, 237±83)(p Conclusions Contrary to previous studies, we did not find significant changes of clinical and electrophysiological data in children after a mean follow-up of 6±5 years. Most of children with spontaneous or inducible AVRT’s at the first evaluation have still inducible AVRT’s at the second evaluation. AP-ERP did not increase significantly.