[A "signal averaging" analysis of the P wave in patients with a history of isolated paroxysmal atrial fibrillation].

The aim of this study was to verify the utility of the signal averaged electrocardiogram for the analysis of the P wave in patients with paroxysmal lone atrial fibrillation. We studied 22 patients with documented paroxysmal atrial fibrillation without cardiovascular or endocrine diseases. The results were compared with 24 normal subjects. Signal averaged electrocardiogram was recorded from bipolar orthogonal leads X, Y, Z using ART equipment mod. 1200 EPX, with 50-250 Hz filter and effective time-base resolution of 100 mm/sec and voltage of 1 mm/microV. Signal averaging of at least 300 beats was performed to reduce noise level under 0.3 microV. In patients with atrial fibrillation the duration of the P wave was significantly longer (135.0 +/- 13.0 msec) than in the normal subjects (109.4 +/- 11.4 msec) (p less than 0.000001). These results were steady in successive recordings (2-30 days after the first recording). The analysis of the P wave signal averaging seems useful in identifying patients with lone paroxysmal atrial fibrillation.