DETECTION OF PATIENTS AT RISK FOR PAROXYSMAL ATRIAL-FIBRILLATION DURING SINUS RHYTHM BY P-WAVE TRIGGERED SIGNAL-AVERAGED ELECTROCARDIOGRAM

To determine whether patients at risk for paroxysmal atrial fibrillation could be detected while in sinus rhythm, the signal-averaged electrocardiogram triggered by P waves was recorded in 42 patients with paroxysmal atrial fibrillation (LP10, LP20, and LP30) for the last 10, 20, and 30 msec and the duration (Ad) of filtered (40-300 Hz) P wave of the spatial magnitude were measured. LP10 and LP20 were significantly lower in the Paf than in the control group (LP10, 1.92 +/- 0.58 versus 2.49 +/- 0.78 mu-V, p < 0.001; LP20, 2.47 +/- 0.78 versus 3.46 +/- 1.20 mu-V, p < 0.0001), although no significant difference in LP30 was found between groups. Ad was also significantly longer in the Paf than in the control group (137.0 +/- 14.3 versus 118.6 +/- 11.3 msec, p < 0.001). These differences between the Paf and control groups remained significant even after dividing by the presence or absence of organic heart diseases. The criteria of "LP20 = 3.5-mu-V or less" and "Ad > 120 msec" as defining "atrial late potential" gave a sensitivity of 91% and a specificity of 76%. These findings suggest that patients at risk for paroxysmal atrial fibrillation could be detected while in sinus rhythm by using the P wave-triggered signal-averaged electrocardiogram.