Antiarrhythmic drugs in atrial fibrillation: an overview of new agents, their mechanisms of action and potential clinical utility

Despite recent advances in our understanding of the mechanism of atrial fibrillation (AF), effective treatment remains difficult in many patients. Pharmacotherapy remains the mainstay of treatment and includes control of ventricular rate as well as restoration and maintenance of sinus rhythm. The currently available antiarrhythmic drugs are particularly effective in converting paroxysmal AF to sinus rhythm and in enhancing the positive effect of electrical cardioversion, but are limited in their efficacy in maintaining sinus rhythm. Moreover, there are limited options in the setting of co-existing ischaemic heart disease, left ventricular dysfunction and structural heart diseases. New drugs added to our clinical armamentarium have been, or are being, developed to combine better efficacy and lack of pro-arrhythmic effects. These developments have gained more interest particularly with the recent debate over rate control versus rhythm control for AF. Although some of these agents are promising, their uptake in clinical practice will not only depend on their efficacy as antiarrhythmic agents but also on their safety in acutely terminating AF and in long-term maintenance of sinus rhythm or rate control in the community.