Importance of using biphasic shock waveforms for cardioversion from atrial fibrillation: an unresolved issue.

Correspondence to: Dr John M Morgan, Southampton University Hospitals, Southampton, SO16 6UY, UK; jmm@ cardiology.co.uk . . . . . . . . . . . . . . . . . . . . . . . I n a previous issue of Heart, Scholten and colleagues presented data to show that a biphasic external atrial defibrillation shock waveform offers no significant advantage over a monophasic shock waveform in current clinical practice. However, there is evidence in this study and elsewhere to suggest that a biphasic defibrillation waveform is ‘‘better’’ than monophasic. The sense that this should be so may be engendered by the past experience of electrophysiologists with ventricular defibrillators and the decrease in defibrillation threshold that was seen with the advent of biphasic shock waveforms in these devices. The question is whether the perceived advantages of biphasic waveforms for atrial defibrillation can be translated into clinical benefit for patients?