Acquisition process of pro-arrhythmic substrate responsible for atrial fibrillation

Summary
Atrial fibrillation is the most common sustained supraventricular arrhythmia and its risk factors include hypertension, valvar disease, and heart failure. Hemodynamic overload of the heart due to these cardiac diseases is thought to cause structural and electrophysiological changes in the atria (atrial remodeling), leading to the onset and persistence of atrial fibrillation. However, the details of the process that leads to the development of atrial fibrillation have not been fully elucidated. In this study, the authors found that structural changes in the atria are clearly visible from week 8 of chronic volume overload; however, a 12-week volume overload period is required before atrial fibrillation becomes persistent. Furthermore, it was found that from week 8 to 12 of chronic volume overload the direction of ion channel gene expression regulation is reversed and that dynamic electrophysiological changes occur. These findings indicate that atrial structural changes induced by chronic volume overload are preceded by electrophysiological changes and that atrial remodeling, centered on electrophysiological changes occurring between weeks 8 and 12, is important for establishment of the pro-arrhythmic substrate responsible for atrial fibrillation.