Dofetilide Reloaded

See Article by Cho et al Atrial fibrillation (AF) is a cause of significant morbidity and mortality, and the available therapies have evolved significantly during the past several decades. In particular, catheter ablation has developed into an increasingly safe and effective treatment option for controlling symptomatic AF. Multiple studies have shown that AF ablation improves quality of life in patients with symptomatic AF, including those with heart failure.1,2 AF ablation can also lead to improved outcomes in patients with heart failure,3 and the results of the CASTLE-AF trial (Catheter Ablation Versus Standard Conventional Treatment in Patients With Left Ventricular Dysfunction and Atrial Fibrillation) recently reported at the European Society of Cardiology Congress showed a mortality benefit in these patients, reporting a significantly lower incidence of death or hospitalization for heart failure in the catheter ablation group compared with optimal medical therapy (28.5% versus 44.6%; P =0.007; http://www.acc.org/latest-in-cardiology/clinical-trials/2017/08/26/01/51/castle-af). Nonetheless, ablation of AF certainly has limitations and is not as effective in patients with persistent AF. Antiarrhythmic drugs remain mainstays of symptomatic AF management, often as an alternative or adjunctive therapy to ablation. Dofetilide is a Vaughan Williams class III antiarrhythmic agent, which blocks the rapid component of the delayed rectifier potassium current ( I Kr): this increases the action potential duration primarily because of delayed repolarization in both atrial and ventricular myocardium. This prolongs the QT but also increases the atrial refractory period and, therefore, terminates reentrant tachyarrhythmias and prevents their reinduction (Tikosyn [dofetilide] capsules package insert; Pfizer, Inc). Dofetilide is important among the antiarrhythmics for multiple reasons. It is one of the most effective antiarrhythmic medications, with ≈60% likelihood of maintaining sinus rhythm for a year4 …