Facilitated electrical cardioversion: does the selection of the antiarrhythmic drug matter?

Abstract

Atrialfibrillation (AF) is a frequent arrhythmia resulting in increased morbidity and mortality. Contemporary therapy with antiarrhythmic drugs (AADs), along with anticoagulants, is complex and suboptimal [1,2] with recurrence rates of AF after conversion to normal sinus rhythm (SR) remaining high also after ablation and cardiac surgery [3]. AF conversion to SR is an integral part of the rhythm strategy which could be accomplished either electrically (cardioversion – ECV) or pharmacologically (PCV). It may be applied in emergency situations, as with hemodynamic deterioration, when ECV is recommended, or on an elective basis. ECV is superior to PCV in terms of efficacy, with an overall success rate close to 90% [4], correlated inversely with the time of presentation, and in terms of safety. However, in 10–30% of cases either AF patients would not respond to ECV (cardioversion failure) or AF recurs shortly after ECV (immediate AF recurrence – IRAF), depending on different factors including technique (i.e. monophasic vs biphasic shock), duration of the AF episodes, presence of comorbidities and degree of evolution of advanced atrial remodeling. On the other hand, AADs are associated with important side effects including proarrhythmia and a low rate (50–60%) of SR maintenance at one year [1,5]. The AADs success rate is even lower if one assumes that up to 60% of recent-onset AF episodes convert spontaneously in less than 48 h and approximatively 30% of converted patients maintain SR at one year without AADs. Refinement in ECV technique could improve the conversion success rate; one example is the so called Ottawa protocol, consisting of four steps differing in electrode position and energy used [6]. Use of AAD pretreatment is an attractive hybridmodality to increase the ECV success rate (facilitated ECV – FECV). In addition to ECV facilitation, AADs use could decrease the risk of IRAF andmay also allow testing the tolerability to a specific AAD. Pretreatmentwith both class III and Ic (Singh-Vaughan-Williams) drugs improved the efficacy of ECV in many AF populations, whereas beta-blockers and digoxin did not demonstrate such virtues [7]. Short-term amiodarone improves restoration and maintenance of SR without significant increase in adverse effects [8]. In small studies verapamil was able to reduce the incidence of IRAF [9], presumably by reducing calcium overload and related atrial remodeling. Small-dose atropine (up to 2mg) is also able to enhance conversion to SR in previously reported “refractory” AF [10]. In a recent