The influence of spontaneous termination of atrial fibrillation on P wave-triggered signal-averaged electrocardiogram

Background: Prolongation of total filtered P wave duration (Ad) and low root mean square voltages for the last 20 ms of the P wave (LP20) on a P wave-triggered signal-averaged electrocardiogram (PSAECG) are typically observed in paroxysmal atrial fibrillation (PAF) patients. A shortening of atrial refractoriness and intra-atrial conduction delay (atrial remodeling) have been shown to occur in response to PAF. We, therefore, investigated the effects of spontaneous termination of PAF on the parameters of PSAECG. Methods: We measured the Ad, LP20 and left atrial (LA) diameter by ultrasonic echocardiography before, within I h after, and 3 and 12 months after PAF termination in patients with no structural heart disease (n=11). Results: The PAF duration was 16+/-5 It. The Ads before, within I h after, and 3 and 12 months after PAF were 137+/-4, 148+/-4, 137+/-6, and 135+/-7 ms, respectively. The Ad within 1 h after PAF was significantly (P<0.01) longer than at the other three acquisition points. Although the LP20 within I h after PAF termination was not significantly different from the other three points, the change in LP20 (within 1 h after PAF-before PAF, -1.1+/-0.4 muV) in the long PAF duration group was significantly (P<0.05) greater than that of the short PAF duration group. LA diameter was unchanged at all points. Conclusion: These data suggest that PAF results in prolongation of Ad after termination of PAF. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.