Reverse atrial electrical remodelling following atrial defibrillation as determined by signal-averaged ECG.

BACKGROUND: Following successful cardioversion for atrial fibrillation (AF), the rate of early recurrence remains high. Analysis of the signal-averaged electrocardiogram of the P wave has been proposed as a noninvasive method of predicting those at risk of recurrence. PURPOSE: To determine the change in signal-averaged P wave duration (SAPWD) following cardioversion from AF, and to determine whether SAPWD is associated with the risk of recurrence. METHODS: SAPWD was determined in 76 patients immediately following successful electrical cardioversion and three days later. Patients were then followed clinically for one year. RESULTS: Recurrent AF was observed in 32 of 76 patients at 90 days following cardioversion. There was no difference in SAPWD immediately following cardioversion (158+/-28 ms versus 164+/-31 ms, P=NS) or three days following cardioversion (152+/-24 ms versus 158+/-36 ms, P=0.4) in patients with and without recurrent AF. There was, however, a significant decrease in the SAPWD during the first three days following cardioversion in the patients who remained in sinus rhythm (158+/-28 ms initially versus 152+/-24 ms on day three, P=0.009). Among the patients with recurrent AF, the decrease was smaller and not statistically significant (161+/-30 ms versus 158+/-36 ms, P=0.3). CONCLUSION: Shortening of the SAPWD occurs following atrial defibrillation in patients who maintain sinus rhythm at 90 days. This provides evidence for reverse atrial electrical remodelling and its association with the maintenance of sinus rhythm.