Antiarrhythmic Agents in Facilitating Electrical Cardioversion of Atrial Fibrillation and Promoting Maintenance of Sinus Rhythm

Abstract

Atrial fibrillation (AF) is a prevalent arrhythmia associated with significant morbidity and mortality. Electrical cardioversion of AF is a potentially definitive treatment, but as little as 67% of patients may be successfully cardioverted and, after normal sinus rhythm (NSR) is achieved, AF often recurs. Class IA, IC, and III antiarrhytmic agents are used for both facilitation of electrical cardioversion and subsequent maintenance of NSR. The mechanisms of these agents may be related to suppressing automaticity, prolonging the wavelength of reentrant wavelets, and preventing electrical remodeling. The possibility of proarrhythmia and other adverse effects complicates use of these drugs, and no large trials have been completed to elucidate definite indications. Several factors may predict failure with electrical cardioversion alone (duration of AF, atrial size, age, underlying disease, and factors that affect transthoracic impedance), calling for empiric pharmacotherapy to facilitate cardioversion. For this purpose, class IA agents hold some promise, evidence for class IC agents is conflicting, and class III agents are the most effective. Adverse effects are rare given the short course before cardioversion, but ibutilide, the most efficacious in this regard, may be proarrhythmic after only a single dose. In promoting maintenance of sinus rhythm, antiarrhythmics across the different classes have similar efficacies: NSR may be maintained in ∼40–65% of patients compared to ∼30–35% with placebo at 1 year. Amiodarone is distinct in its success, with ∼60–80% of patients remaining in NSR. For all of these agents, long-term therapy may lead to proarrhythmia or other substantial adverse effects. Finally, a serial antiarrhythmic strategy may be effective, with maintenance of NSR and minimal adverse effects ultimately achieved by trial and error.

Cardioversion of acute atrial fibrillation in the short observation unit: comparison of a protocol focused on electrical cardioversion with simple antiarrhythmic treatment

“…It is hypothesised that this result is due to the delivery of higher biphasic energies as first DCC shock (200 J in 84% of attempts), which is suggested by some authors to limit the number of shocks,17 and to the DCC-enhancing property of amiodarone,18 the most used drug in the DCC-cohort. Indeed, it is more likely that amiodarone played the role of increasing the likelihood of success of DCC rather than the role of restoring sinus rhythm directly, for its known delayed cardioverting capacity 9…”

The Cox-maze IV procedure for lone atrial fibrillation: a single center experience in 100 consecutive patients

“…AF accounts for about 25% of all strokes in patients older than 80 years and increases a person's risk of stroke by fivefold [3]. The limitations of pharmacological therapy for AF have led to the development and proliferation of interventional approaches to treat this arrhythmia over the last two decades [4–7]. These have included catheter ablation and surgery.…”

The Cox-Maze Procedure for Lone Atrial Fibrillation

“…3 The limitations of pharmacological therapy with failure rates as high as 60% have led to the development and proliferation of interventional approaches in the treatment of AF, including catheter ablation and surgery. 4–7 …”