Over the past decade, several mapping studies of human atrial fibrillation (AF) have made the following important observations: (1) Atrial electrograms during sustained atrial fibrillation have three distinct patterns: single potential, double potential, and complex fractionated potential(s) (CFAEs).1–3 (2) The distribution of these atrial electrograms during AF localizes to specific atrial sites, and these electrograms exhibit remarkable temporal and spatial stability.1,2 (3) The CFAE areas represent AF substrate sites and are important targets for AF ablation.
