Inducibility of atrial fibrillation before and after radiofrequency catheter ablation of accessory atrioventricular connections.

INTRODUCTION The purpose of this study was to evaluate the inducibility of atrial fibrillation in patients with an accessory atrioventricular connection (AAVC) and to determine if the inducibility of atrial fibrillation is altered after successful radiofrequency catheter ablation of the AAVC. METHODS AND RESULTS Thirty-seven patients with an AAVC and 36 control patients were prospectively evaluated using a standardized atrial pacing protocol. The high right atrium was paced using a 25-beat drive train, 1.5-second intertrain pause, 10-mA pulse amplitude, and 2-msec pulse duration at cycle lengths of 250 to 100 msec, in 10-msec decrements. Pacing was performed twice at each cycle length. Thirty patients with an AAVC underwent repeat atrial overdrive pacing after successful radiofrequency ablation of the AAVC. Atrial fibrillation was induced in 26 (70%) patients with an AAVC and 22 (61%) controls (P = NS). Atrial flutter was induced in 11 (30%) patients with an AAVC and 13 (36%) controls (P = NS). The cumulative percentage of patients with atrial fibrillation/flutter induced at each pacing cycle length was the same in each group. There was no difference in the duration of atrial fibrillation/flutter between control patients and patients with an AAVC. Among the 30 patients who underwent repeat atrial overdrive pacing after radiofrequency ablation of an AAVC, there was no difference in the inducibility or duration of atrial fibrillation/atrial flutter after ablation compared to baseline. CONCLUSION These findings indicate that the vulnerability of the atrium to fibrillate in response to atrial pacing is independent of the presence of an AAVC.