[Biphasic shock waveform for cardioversion of atrial fibrillation in the emergency room].

Unlabelled: Transthoracic electrical cardioversion, traditionally monophasic shock waveform, has been a mainstay of the therapy for atrial fibrillation (AF) since its introduction into clinical practice. Recent studies have demonstrated that biphasic shock is more efficient than monophasic shock waveforms for terminating both ventricular fibrillation and AF; however, data on the recommended initial shock energy in conversion of AF by biphasic shocks are limited.
Aim: Our study aimed to evaluate the optimal dose of the initial shock energy for conversion of AF to sinus rhythm by transthoracic biphasic shock waveforms in the Emergency Room (ER).
Methods and Results: A total of 144 consecutive patients, who came to the ER because of AF, were our study population. All patients underwent cardioversion via anterior-laterally positioned hand-held electrode paddles. Patients received sequential shocks of 50 J (only the first 40 patients), 100 J, 150 J and 200 J if necessary. There was a significantly greater cumulative conversion success rate with 100 J (70.5%) than 50 J shock energy (55%), p < 0.05; but even greater with 150 J (89%) than 100 J shock energy, p < 0.003; no significant difference was observed between 200 J (94%) and 150 J shock energy, p < 0.58. Nine of 12 patients, whose body weight was less than 70 kg, were successfully converted to sinus rhythm (75%) by 50 J shock 1 energy. After cardioversion there were reports of: a five seconds asystole observed in 1 patient; pulmonary edema in another patient; hypotension was reported in 1 patient and mild erythema in 14 patients (9.7%).
Conclusion: Our findings support that biphasic waveform shock energy of 150 J is advised as a first attempt, but in patients with a body weight less than 70 kg. lower energy shock may be used.