Improvement of atrial signal-averaged electrocardiographic abnormalities after radiofrequency catheter ablation in persistent atrial flutter.

It has been reported that abnormalities of atrial conduction are present in patients with atrial flutter (AFL). We analyzed the P wave signal-averaged ECG (PSE) in patients after cardioversion of chronic AFL by radiofrequency catheter ablation (RFCA) to determine whether abnormalities of atrial conduction exist in patients with AFL and whether they recover. We studied 11 patients undergoing ablation of persistent AFL (AFL group), 11 patients with paroxysmal AFL (PAFL group), and 14 patients without any evidence of arrhythmias (control group). The PSEs were recorded 1 day, 7 days, and 1 month after RFCA. The filtered P wave duration (FPD) was calculated from the PSE recording. The FPD correlated with interatrial conduction time (r = 0.644) and left atrial dimension (r = 0.675) in combined assessment of the AFL and PAFL groups. The FPD was longer in the AFL group 1 day (165 +/- 14 ms, P < 0.001) and 1 month (150 +/- 18 ms, P < 0.05) after RFCA than in the control group (134 +/- 10 ms). Our findings suggest that atrial conduction abnormalities detected by PSE are present in patients with persistent AFL and improve 1 month after cardioversion.