18. Atrial Fibrillation: Electrical Cardioversion and Drug Prophylaxis

Initial energy (IE) of 200 J or greater is recommended for external electrical cardioversion (EC) of Atrial Fibrillation (AF) with monophasic waveform (MW). Devices that deliver current with a biphasic waveform (BW) appear to achieve EC at lower energy levels than that use a MW. The aim of the present study was to evaluate the influence of several factors (age, body-weight, ejection fraction, left atrial diameter, AF duration) on the results of EC with BW. 105 patients (pts) (59 male and 46 female, mean age 70 ± 8 yrs) underwent EC. Before EC, all pts were treated with oral anticoagulant for 4 weeks until the INR value achieved between 2.5 and 3, and with different antiarrhythmic drugs (sotalol, propafenone, flecainide, amiodarone). EC was done under general anaesthesia, in the presence of anaesthetist. The initial energy used for the first shock was 50 J/100 J, increasing up to 150-200 J, if the first shock unsuccessful (protocol 50/100J to 150-200 J). Reversion of AF to sinus rhythm was obtained in 92 % of the pts. Correlated with shock energy of 50 J, 100 J, 150 J, 200 J, the successful CE was found for the body-weight 69 ± 5, 70 ± 12, 78 ± 4 and 80 ± 9 kg, respectively. There was no statistical different between the four groups, regarding age, left atrial diameter, ventricular systolic function, duration of arrhythmia. In conclusion, an IE of 50 J could be used in pts weighing ⊂ 75 kg, an IE of 100 J could be used in pts with weight ⊇ 75 but ⊆ 82 kg, while for pts with a weight ⊃ 82 kg an IE of 150 J should be recommended.