Safety and efficacy of low-energy cardioversion of 500 patients using two different techniques

Aim To present some safety and efficacy issues of low-energy internal cardioversion of chronic atrial fibrillation from 500 consecutive procedures performed with two different techniques, using either two single-coil catheters, or a single twin-coil catheter. Methods and Results Low-energy internal cardioversion was carried out in 368 patients by means of two defibrillation catheters: the former was positioned in the right atrium and the latter either in the left pulmonary artery (212 patients), or in the distal coronary sinus (156 patients). In the remaining 132 patients, a single twin-coil catheter was positioned with the distal coil either in the pulmonary artery (75 patients) or in the coronary sinus (57 patients), while the proximal coil was in the right atrium. The external defibrillator delivered truncated biphasic shocks (6/6 ms, tilt 50%), with a voltage of 10–400 V. In 283 patients (57%) external cardioversion had been unsuccessfully tried before low-energy internal cardioversion. After a total of 1118 shocks, the overall success rate was 92·2% (91·3% with two catheters and 94·7% with the single catheter); the success rate was 93·4 and 91·3% with the coronary sinus and the pulmonary artery approach, respectively. The mean energy used was 6·5±3·4 J (voltage: 320±45 V); no difference was found between the twin catheter (6·3±3·1 J) and the single catheter approach (6·9±3·7 J), while the coronary sinus configuration required a significantly lower energy than the pulmonary artery configuration (5·6±2·9 vs 7·2±3·8 J, P<0·05). The duration of the current atrial fibrillation episode was the only clinical characteristic statistically different between the 461 successfully cardioverted patients and the 39 failures (295 vs 727 days, P<0·01). No complication was recorded during or after the delivery of the therapy; no procedure had to be terminated because of patient's intolerance. Conclusions Low-energy internal cardioversion is a safe and effective procedure for converting chronic atrial fibrillation, confirmed by this large multicentre experience. The newly available twin-coil catheter seems to achieve a slightly better success rate compared with the traditional two-catheter technique, and is associated with the same safety profile.