Catheter ablation of atrial flutter due to amiodarone therapy for paroxysmal atrial fibrillation

Aims Antiarrhythmic drug treatment for atrial fibrillation can cause atrial flutter-like arrhythmias. The aim of this study was to clarify the effect of catheter ablation of the tricuspid annulus-vena cava inferior isthmus on amiodarone-induced atrial flutter and to determine the incidence of atrial fibrillation after catheter ablation of amiodarone-induced atrial flutter in comparison to regular typical flutter. Methods and Results Among 92 consecutive patients with typical atrial flutt er who underwent isthmus ablation 28 patients had atrial flutter without a history of previous atrial fibrillation (group I), 10 patients had atrial f lutter following the initiation of amiodarone therapy for paroxysmal atrial fibrillation (group IT) and 54 patients had atrial flutter and atrial fibr illation (group III). Atrial cycle length during atrial flutter in amiodaro ne-treated patients (group II) (277 +/- 24 ms) was significantly longer as compared to the cycle length of atrial flutter in group I (247 +/- 33 ms) a nd group ITT patients (235 +/- 28 ms). The rate of successful transient ent rainment and overdrive stimulation to sinus rhythm was not different betwee n patients with (60%) or without amiodarone therapy (group I: 71%, group II I: 53%). Successful isthmus ablation with bidirectional conduction block el iminating right atrial flutter was achieved in 90% of amiodarone-treated pa tients and 93% of patients without amiodarone therapy. In the amiodarone-tr eated patient group atrial conduction times during pacing in sinus rhythm w ere significantly prolonged by 20-30% before and after ablation in all regi ons of the reentrant circuit. During a mean follow-up of 8 +/- 3 months pos t-ablation, atrial fibrillation recurred in two of 10 patients on continued amiodarone therapy after successful isthmus ablation. Thus, successful cat heter ablation of atrial flutter due to amiodarone therapy was associated w ith a markedly lower recurrence rate of paroxysmal atrial fibrillation (20% ) as compared to patients with atrial flutter plus preexisting paroxysmal a trial fibrillation (76%) and was similar to the outcome of patients with su ccessful atrial flutter ablation without preexisting atrial fibrillation (2 5%). Conclusion These data suggest that isthmus ablation with bidirectional bloc k and continuation of amiodarone therapy is an effective therapy for the tr eatment of atrial flutter due to amiodarone therapy for paroxysmal atrial f ibrillation.