Oxidative stress and atrial fibrillation – association or causation?

Atrial fibrillation (AF) is the commonest arrhythmia, with >8 million people in the European Union estimated to have AF in 2010. 1 AF increases mortality at least 1.5-fold, is responsible for an increase in embolic strokes, and can also cause a range of debilitating symptoms.At present, treatments for AF, especially persistent AF, have limited success.Catheter ablation, which is a key treatment for AF, has a ceiling of success of approximately 50% in persistent AF.A possible reason for the lack of success in treating persistent AF may be that current antiarrhythmic medications and ablation strategies do not adequately target the underlying mechanisms of AF and its pathophysiology. 2he pathophysiology of AF is complex.The pulmonary veins are important triggers for AF, and a number of electrophysiological (e.g.reduced IK1 and ICa-L currents) and anatomical (branching fibers with limited lateral coupling and abrupt fiber orientation change) features predispose the pulmonary veins to ectopy. 3This has led to electrical isolation of the pulmonary veins being the cornerstone of AF ablation.However, the triggers are only part of the story, and remodeling of the atrial substrate is equally, if not