CLINICAL RECURRENCES AFTER SUCCESSFUL ACCESSORY PATHWAY ABLATION - THE ROLE OF DORMANT ACCESSORY PATHWAYS

Introduction: Recurrence of clinical symptoms after radiofrequency cat heter ablation of an accessory atrioventricular pathway (AP) may be du e to the late manifestation of an additional AP that was not detected during the initial ablation session, It was the purpose of this study to elucidate the phenomenon of these ''dormant'' APs, Methods and Resu lts: Of 1280 consecutive patients who underwent radiofrequency cathete r ablation of an AP, 54 patients (4.2%) developed clinical symptoms po stablation, necessitating a repeat ablation session, Recurrence of con duction over the AP targeted at the initial ablation session was found in 45 patients, whereas in the other 9 patients (0.7%) the manifestat ion of a previously unnoticed AP had caused symptom recurrence, Retros pective analysis of the data from these patients' ablation sessions re vealed that the late manifesting AP was ablated at a site clearly diff erent from that of the initially targeted AP, and that the manifestati on of conduction over a previously ''dormant'' AP occurred significant ly later than the recovery of a presumably ablated AP, Seven (78%) of the 9 ''dormant'' APs were concealed, and none exhibited decremental c onduction properties, Conclusion: The incidence of clinical recurrence s mediated by the late manifestation of conduction over a previously ' 'dormant'' AP is low, The lack of an anatomic vicinity of these predom inantly concealed APs with the initially targeted AP and the lack of e vidence for their presence during the initial ablation session suggest intermittent conduction as the most likely explanation for their late manifestation.