Direct current electrical cardioversion (DC-ECV) is the preferred treatment for the termination of paroxysmal atrial fibrillation (AF) that occurs during radiofrequency ablation (RFA) of supraventricular tachycardias (SVT). Intravenous Ibutilide may be an alternative option in this setting. Thirty-four out of 386 patients who underwent SVT-RFA presented paroxysmal AF during the procedure and were randomized into receiving ibutilide or DC-ECV. Ibutilide infusion successfully cardioverted 16 out of 17 patients (94%) within 1 7 . 3 7 ± 7 . 8 7 ？min. DC-ECV was successful in all patients (100%) within 1 7 . 2 9 ± 3 . 0 4 ？min. Efficacy and total time to cardioversion did not differ between the study groups. No adverse events were observed. RFA was successfully performed in 16 patients (94%) in the ibutilide arm and in all patients (100%) in the DC-ECV arm, p = NS. In conclusion, ibutilide is a safe and effective alternative treatment for restoring sinus rhythm in cases of paroxysmal AF complicating SVT-RFA. 1. Introduction Radiofrequency catheter ablation (RFA) has been established as an effective treatment for supraventricular tachycardias (SVT) [1, 2]. Paroxysmal atrial fibrillation (AF) may occasionally complicate SVT-RFA, resulting in repetitive electrical cardioversions and undesirable procedure delays. Ibutilide is a newer class III antiarrhythmic agent for the cardioversion of AF and atrial flutter [3–5]. Unlike other class III agents which block the rapid component of the delayed rectifier outward potassium channels (Ikr), ibutilide activates the slow inward currents (mainly sodium current). These antiarrhythmic actions result in prolongation of action potential duration and refractoriness of normal myocardial tissue [3–5] and, therefore, the termination of re-entry arrhythmias such as atrial fibrillation and atrial flutter. However, ibutilide may also result in prolongation of the QT interval and increased risk for polymorphic ventricular tachycardias [4, 6, 7]. The safety of ibutilide in terminating paroxysmal atrial fibrillation has been previously shown in various populations [8]. The effect of ibutilide in the setting of electrophysiological testing and ablation procedures has not been adequately studied. The aim of this study was to assess the safety and efficacy of ibutilide versus direct current electrical cardioversion (DC-ECV) for the termination of paroxysmal AF complicating RFA for supraventricular tachycardias. 2. Methods 2.1. Patient Population Over a period of 47 months, 386 patients undergoing RFA for SVT in our laboratory were
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