Facilitating internal cardioversion of chronic atrial fibrillation with ibutilide - predictors of atrial defibrillation-threshold decrease

Background: Internal atrial cardioversion has been successfully used in the treatment of atrial fibrillation. The object of this study was to depict the effect of ibutilide on sinus rhythm restoration and internal atrial defibrillation threshold in patients with chronic atrial fibrillation. Material/Methods: Twenty-four patients (14 men and 10 women, mean age 63.16 +/- 8.55 years) with chronic atrial fibrillation were cardioverted using a single-lead system. The distal coil of the defibrillator catheter was placed in the coronary sinus and the proximal coil at the junction of the superior vena cava and the high right atrium. Synchronized biphasic shocks were applied using a step-up protocol from 1 to 30 joules until sinus rhythm was restored. In all patients with successful cardioversion, atrial fibrillation was reinduced and second cardioversion was attempted after intravenous administration of 1 mg ibutilide. Results: Successful internal cardioversion was achieved in 22 (91.6%) and 23 (95.83%) patients before and after ibutilide administration, respectively. The amount of energy given was reduced from 13.89 +/- 11.44 to 8.28 +/- 9.64 joules (p=0.0001). Variables associated with the reduction of the defibrillation threshold after ibutilide administration were: duration of the last episode of atrial fibrillation (p=0.008), time since the first episode of atrial fibrillation (p=0.002), body mass index (p=0.01), ejection fraction (p=0.025), male gender (p=0.001), and diameter of the left atrium (p=0.028). Conclusions: Internal atrial defibrillation after ibutilide administration is a safe and effective method for sinus rhythm restoration, with concurrent significant reduction of the atrial defibrillation threshold.