Detection of patients at risk for recurrence of atrial fibrillation after successful electrical cardioversion by signal-averaged P-wave ECG.

The aim of the study was to assess the value of signal-averaged ECG of P-wave in predicting recurrence of atrial fibrillation after direct-current electrical cardioversion of chronic atrial fibrillation. The signal-averaged ECG triggered by P-wave was recorded in 35 patients after successful electroconversion. Duration of the high frequency P-wave and the root mean square voltages for the last 20 ms (RMS20) P-wave of the vector magnitude were calculated. After 6 months follow-up recurrence of atrial fibrillation was observed in 11 patients (group I) and in 24 patients sinus rhythm was maintained (group II). A filtered P-wave was significantly longer in group I with recurrence of atrial fibrillation, than in patients from group II who maintained sinus rhythm (145+/-11.8 vs 130+/-10.8 ms, p<0.001). RMS20 was significantly lower in group I than in patients from group II (1.6+/-0.6 vs 2.2+/-0.9 microV, p<0.02). A filtered P-wave of duration >q37 ms associated with a RMS 20 ms <1.9 microV had a sensitivity of 73% and specificity of 71% for the detection of patients with recurrence of atrial fibrillation after successful direct-current electrical cardioversion of chronic atrial fibrillation. These results suggest that signal-averaged ECG of P-wave may be helpful for identification of patients with recurrence of atrial fibrillation after successful direct-current electrical cardioversion.