[Electrical cardioversion for atrial fibrillation: advantages of the transthoracic biphasic method].
BACKGROUND
The purpose of this study was to evaluate efficacy and safety of biphasic shock for atrial fibrillation cardioversion to sinus rhythm. A second endpoint was to evaluate myocardial damage by means of cardiac troponin I dosage.


METHODS
We studied 164 patients, with drug-resistant atrial fibrillation (208 episodes). Group A patients underwent biphasic shock normalized with respect to weight: 50 J (weight < 60 kg), 70 J (weight 61-84 kg) and 100 J (weight > 84 kg; the second and third shocks were 2 and 3 times higher than the first. Group B underwent sequential monophasic shock of 200, 300 and 360 J. Troponin I was evaluated at baseline, and 6, 12 and 24 hours after cardioversion.


RESULTS
Total efficacy was 92% for biphasic shock and 89% for monophasic shock. First-shock efficacy with biphasic waveform (57.3%) was significantly greater than with first monophasic waveform (21.5%) (p = 0.000). Cardiac troponin I increased from 0.4 +/- 1.1 to 0.8 +/- 2.2 compared to a normal value of 2 ng/ml.


CONCLUSIONS
For transthoracic cardioversion of atrial fibrillation, biphasic shock has a greater efficacy requiring less energy compared to monophasic shock. Normal mean values of cardiac troponin I proved the absence of myocardial damage.
Divisione di Cardiologia, Ospedale Santo Spirito, Roma. dracar@virgilio.it
Alessandro
A
Carunchio
Maurizio
M
Burattini
Claudio
C
Coletta
Luciano
L
Pandolfo
Andrea
A
Porzio
Fabrizio
F
Zecchini
Vincenzo
V
Ceci
D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000209:etiology / Q000628:therapy*; D004554:Electric Countershock / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D016896:Treatment Outcome