Biatrial electrograms during coarse atrial fibrillation and flutter-fibrillation.

Right and left atrial electrograms were recorded in 57 patients who demonstrated coarse atrial fibrillation or flutter-fibrillation on the scalar electrocardiogram. Atrial electrograms in coarse atrial fibrillation most often showed biatrial fibrillation with periodic slowing and regularity, while dissimilar interatrial or right intra-atrial rhythms were noted less frequently. Flutter-fibrillation on the scalar ECG required the presence of rapid regular tachysystole (flutter) somewhere in the atria and was usually associated with dissimilar interatrial or right intra-atrial rhythms, dissimilar atrial flutter rates, or fast or fragmented flutter. Coarse atrial fibrillation and flutter-fibrillation may be secondary to a variety of atrial electrical events.