Introduction: In almost 20% of patients with persistent atrial fibrillation (AF), electrical cardioversion is unsuccessful because of shock failure (i.e., no single sinus beat) or immediate reinitiation of AF (IRAF; recurrence within 2 min). Relative prevalence of shock failure and IRAF are not well known because data on outcome of electrical cardioversion therapy mostly do not distinguish shock failure from IRAF.
Methods and results: In this review, the role of pretreatment with antiarrhythmic drugs on prevention of shock failure and total outcome of the cardioversion procedure are investigated. Quinidine and propafenone seem to be effective in preventing IRAF. Verapamil given in addition to Class I or III drugs may strengthen the preventive effects of these drugs than if they were given alone. Ibutilide prevents shock failure, although neither ibutilide nor dofetilide seems to be effective in preventing IRAF.
Conclusion: Pretreatment with antiarrhythmic drugs may enhance cardioversion outcome predominantly by preventing IRAF. Different antiarrhythmic drugs within the same Vaughan-Williams class have different effects on shock failure and IRAF.