Natural time course of atrial fibrillation. Shown is a typical chaotic pattern of time in atrial fibrillation (black) and time in sinus rhythm (grey) over time (x-axis). Atrial fibrillation progresses from undiagnosed to first diagnosed, paroxysmal, persistent, to permanent. Flashes indicate cardioversions as examples for therapeutic interventions that influence the natural time course of the arrhythmia. Reproduced with permission from .