[Spatial distribution of atrial late potentials on body surface mapping in patients with paroxysmal atrial...

We investigated the spatial distribution of atrial late potentials (ALP) in patients with paroxysmal atrial fibrillation (Paf) by use of body surface signal-averaged ECG. The P wave-triggered signal-averaged ECG was recorded in 20 patients with Paf and 34 control patients from precordial 16 unipolar leads (standard V1-V6 and two intercostal spaces below and above V1, V2, V4-V6). The duration (Ad) and number of fragmented deflection (Nf) of filtered P wave were measured on each lead. % Area was also calculated by dividing the area for the last 20 msec by the total area of filtered P wave. The lead having any of a significantly longer Ad, larger Nf and smaller % Area in patients with Paf than the controls was designated as ALP positive lead. ALPs were observed in all other than two intercostal spaces above V5 and V6. This finding suggests that the electrophysiological disparity in the whole atrial muscle might be involved in patients with Paf.