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 1 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 h. The Ads before, within 1 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 1 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 μV) 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.