Low energy intracardiac cardioversion of persistent atrial fibrillation

The aims of the study were to verify the efficacy and safety of low energy internal cardioversion (LEIC) in patients with persistent atrial fibrillati on (AF) and to identify the factors affecting the atrial defibrillation thr eshold (ADT). Forty-nine patients with persistent (lasting greater than or equal to 10 days) AF underwent LEIC. In each patient, two 6 Fr custom-made catheters with large active surface areas were positioned in the coronary s inus (cathode) and the lateral right wall (anode), respectively, for shock delivery, and a tetrapolar lead was placed in the right ventricular apes fo r R wave synchronization. Truncated, biphasic (3 ms + 3 ms), exponential sh ocks were used, beginning at 50 V and increasing in steps of 50 V until sin us rhythm had been restored. Mild sedation (diazepam 5 mg IV) was administ ered to 12 patients. Sinus rhythm nas restored in all the subjects with mea n voltage and energy levels of 352.0 +/- 80.3 V and 8.2 +/- 3.4 J, respecti vely. The ADT in patients pretreated with amiodarone (6.4 +/- 1.8 J) was lo wer than that of patients who had not received any antiarrhythmic drugs (9. 2 +/- 3.7) (P = 0.04). No ventricular arrhythmias were induced by any of th e atrial shocks, and no other complications were observed. During a mean fo llow-up of 162.9 +/- 58.7 days, AF recurred in 21 (43%) patients; 71% of th ese occurred in the first week after cardioversion. LEIC is effective in re storing sinus rhythm in patients with persistent AF. The technique seems to be safe and does nor require general anesthesia or, in most cases, sedatio n. Patients pretreated with amiodarone have lower ADTs.