ELECTROGRAM PATTERNS ASSOCIATED WITH SUCCESSFUL RADIOFREQUENCY ABLATION OF ACCESSORY PATHWAYS IN CHILDREN

Electrograms observed prior to successful and unsuccessful ablation tr ials in 33 patients (362 attempts) with manifest pathways and 18 patie nts (194 attempts) with concealed pathways were compared to identify t he electrogram patterns that are associated with successful radiofrequ ency ablation of accessory atrioventricular connections in young patie nts (mean age 12.7 years; range 4-22 years). Success was defined as pe rmanent or transient interruption of conduction in the accessory conne ction. Predictors of success in patients with manifest pathways were l ocal ventricular preexcitation (p = 0.0001), left-sidedness (43 or 174 ) of the accessory connection compared (p = 0.04) to right-sidedness ( 27 of 172), a probable Kent bundle potential (29 of 84 versus 39 of 25 6; p = 0.0001), and short antegrade atrioventricular conduction interv als (53.1 +/- 31.9 ms versus 64.6 +/- 32.0 ms; p = 0.02). Predictors o f success in patients with concealed pathways were short ventriculoatr ial conduction times (103.3 +/- 35.8 ms versus 117.9 +/- 34.8 ms; p = 0.01), and left-sided (42 of 125) pathways (p = 0.03; versus right-sid ed, 11 of 60), The presence of a Kent bundle potential was not signifi cant. We conclude that specific electrogram patterns can predict succe ssful ablation of either manifest or concealed accessory pathways. Use of these criteria may reduce the delivery of unnecessary energy to yo ung myocardium.