Ibutilide is a class III antiarrhythmic drugs used intravenously for chemical cardioversion of atrial fibrillation (AF) and atrial flutter (AFL). It mainly acts by blocking the rapid component (I kr ) of delayed rectifier K + channels, resulting in prolongation of action potential duration in atrium. Ibutilide fumarate is a methanesulfonamide derivative that is structurally similar to sotalol without the β-adrenoreceptor blocking activity. The success rate of cardioversion with ibutilide of atrial flutter is in the range of 50–70%, whereas its efficacy for conversion of atrial fibrillation is 30–50%. As compared to ibutilide, coadministration with propafenone has a significantly higher success rate of for AF termination. Ibutilide is also effective in pre-excited AF to prevent AF related ventricular tachycardia and the risk of sudden cardiac death. It is safe drug to use for cardioversion in patients on chronic amiodarone therapy. The main side effect of dofetilide is torsade de pointes occurs in 4% patients and monomorphic ventricular tachycardia in 4.9% patients. Proadministration of magnesium reduces the risk of torsade de pointes. Patients should be monitored for at least 4 hours for tdp. Targeting complex fractionated electrograms during catheter ablation of persistent AF has shown mixed results. Conversion rate with ibutilide infusion is only 30% in the presence of an enlarged left atrium (> 5 cm) and 37.7% in the presence of mitral valve disease (MVD), whereas the conversion rate was 82.5% in the absence of MVD and 85% in the absence of both enlarged left atrium and mitral valve disease (p = <0.001). Ibutilide can be used effectively in patients who are not a candidate for direct current cardioversion or who chose not to undergo electric cardioversion.
Britto et al. (Sun,) studied this question.