ANALYSIS OF THE P-WAVE WITH SIGNAL AVERAGING TO ASSESS THE RISK OF ATRIAL-FIBRILLATION AFTER CORONARY-ARTERY BYPASS-SURGERY

P wave signal averaging was performed in 91 consecutive patients under going coronary artery bypass grafting to detect patients at risk of po stoperative atrial fibrillation (AF). Sixteen patients (17.5%) develop ed AF after surgery. The P wave duration on the signal-averaged electr ocardiogram (EGG) and on surface ECG was prolonged in AF patients comp ared to others (respectively 141 +/- 12 vs. 132 +/- 12 ms and 124 +/- 9 vs. 113 +/- 9 ms). The root mean square voltages (RMS) of the total P wave were not different between the two groups; the RMS of the late portion of the P wave (late RMS) was significantly higher (0.25 +/- 0. 15 vs. 0.17 +/- 0.10 mu V) and the RMS of the first 110 ms of the P wa ve (early RMS) significantly lower(0.88 +/- 0.28 vs. 1.09 +/- 0.33 mu V) in AF. The late/???? early RMS ratio was different(0.29 +/- 0.16 vs . 0.17 +/- 0.11). In a multivariate analysis only age and the late/ear ly RMS ratio were predictive for AF.