[Biphasic versus monophasic shock waveforms for transthoracic cardioversion of atrial flutter in the emergency room]

Transthoracic electrical cardioversion (ECV), traditionally using monophasic waveform (MW) shock, has an important role in the treatment of symptomatic atrial flutter (AFI). Biphasic waveform (BW) shock has been demonstrated to be more successful than MW shock for termination of atrial fibrillation, but data about its use for ECV of AFI are limited.

We retrospectively analyzed the records of 53 patients (pts) admitted -to the ER due to symptomatic AFl during the period August 2004 to August 2005: 31 pts received BW shock and 22 pts MW shock. The type of shock waveforms and the initial energy of CV were chosen by the doctor on duty in the ER; the lower energy for ECV was 20 joules, which was increased to 50, 100 and 200 joules if necessary. There were no significant differences between the clinical characteristics of the pts who received BW shock or MW shock. All pts underwent ECV via anterior-laterally positioned hand-held electrode paddles. Successful ECV by BW shock and MW shock was 41% and 42% of the pts, respectively, using 20 joules of energy (p=n.s.); 77% and 80% using 50 joules (p=n.s.); 93% and 90% using 100 joules (p = n.s.); 100% of successful ECV was reached when 200 joules of energy was used, regardless of waveforms type. Median energy for successful ECV was 50 joules in both types of electrical waveforms. No complications were reported.

There were no significant differences in the success rates of conversion of atrial flutter to sinus rhythm by BW or MW shock. We recommend 50 joules for starting energy of ECV of AF1 regardless of waveforms type.