[Transthoracic cardioversion in patients with atrial fibrillation: comparison of three different waveforms].
BACKGROUND
Transthoracic electrical cardioversion represents the most effective therapy in converting atrial fibrillation (AF) to sinus rhythm. External cardioverter-defibrillators discharge a current with monophasic and most recently biphasic waveforms. Lately, many articles support the superiority of the biphasic waveform over the monophasic one. Moreover, we have the opportunity to use different biphasic waveforms. The aim of this study was to compare the efficacy (success rate and energy delivered) of a monophasic wave and two different biphasic waves, in patients with persistent AF undergoing external electrical cardioversion. The monophasic wave was delivered by a Zoll M series NM PDMA-9, while the so-called "rectilinear" biphasic waveform was used by a Zoll M series PDM-7S and the biphasic truncated exponential wave by a Laerdal Heartstart 4000.


METHODS
Sixty-four patients with clinical indications to undergo external electrical cardioversion were randomized into three groups. All the groups were homogeneous for almost all characteristics, particularly atrial dimensions, body surface area, and duration of AF and therapy. Eighteen patients underwent external cardioversion with monophasic waveform (group 1), 22 patients were treated with rectilinear biphasic waveform (group II), and 24 patients with biphasic truncated waveform (group III). A cardioversion protocol, providing up to 5 shocks, with incremental energy levels was used. A blood sample was obtained 6 hours later to evaluate myocardial damage due to shock therapy for each patient.


RESULTS
Both biphasic devices demonstrated to be more effective than the monophasic one (group I 78%, group II 95%, group III 100%). Moreover, none of them caused any significant myocardial damage, evaluated in terms of cardiac enzyme release. Nonetheless, the biphasic truncated exponential wave demonstrated an efficiency of 10 0% compared to 95 % of the rectilinear one and 78% of the monophasic one, using less energy/patient (873 +/- 101 J group I, 390 +/- 48 J group II, and 280 +/- 42 J group III), at almost the same shock attempts.


CONCLUSIONS
Biphasic truncated exponential wave seems to be more effective at a lower energy level.
Santomauro
Maurizio
M
Dipartimento di Cardiologia, Università degli Studi Federico II, Napoli. santomau@unina.it
Borrelli
Alessio
A
Ottaviano
Luca
L
Costanzo
Angelo
A
Monteforte
Nicola
N
Duilio
Carlo
C
Chiariello
Massimo
M
D001281:Atrial Fibrillation / Q000628:therapy*; D004554:Electric Countershock / Q000379:methods*; D004594:Electrophysiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013909:Thorax