[The newly developed algorithm for signal-averaging ECG of P wave]

Signal-averaged P waves are available to evaluate patients at risk for paroxysmal atrial fibrillation. We developed a new algorithm of P wave triggered signal-averaged ECG applied the cross-correlation technique. Subjects consisted of 13 patients with paroxysmal atrial fibrillation (PAF group) and 12 normal volunteers (NOR group). ECG signals were amplified (5,000 times), filtered with band-pass filter (60-300 Hz) and averaged about 500 beats. The root mean square voltage for the total filtered P wave (P-RMS) and the duration of filtered P wave (FPD) were measured and were compared with those parameters obtained by level-slice P triggered method and R triggered method. The value of P-RMS in the all subjects was significantly higher by the cross-correlation method than that by the level-slice P triggered method (264 msec.microV versus 235 msec.microV, P < 0.001). The value of FPD in the PAF group was also significantly longer by the cross-correlation method than that by the level-slice P triggered method (151 msec versus 146 msec, P < 0.05). In conclusion, the cross-correlation method is suited for assessing P waves by the signal-averaged ECG.