Nature of electrogram fractionation during atrial fibrillation.

The study by Jadidi et al1 described the locations of areas of continuously fractionated atrial electrograms during atrial fibrillation (AF) using high-resolution endocardial mapping in 9 patients with paroxysmal AF and 9 patients with persistent AF. This study then correlated these areas with the locations of fractionated atrial potentials during sinus rhythm and coronary sinus (CS) pacing in the same patients. Their premise was that fractionation resulted from conduction abnormalities (conduction slowing/block, pivot points, asynchronous activation, and wave collision).2,3 They postulated that areas exhibiting fractionation during all 3 rhythms (AF, sinus rhythm, and CS pacing) may differentiate fixed atrial/anatomic substrate (structural remodeling) from wave collision or functional slow conduction. They were hopeful that a better understanding of these patterns would help identify which of the areas of fractionation were optimal targets for ablation.