ATRIAL LATE POTENTIALS IN PATIENTS WITH PAROXYSMAL ATRIAL-FIBRILLATION DETECTED USING A HIGH-GAIN, SIGNAL-AVERAGED ESOPHAGEAL LEAD

High gain, signal-averaged ECGs using conventional surface lead techni que and a transesophageal lead technique were performed in 45 idiopath ic paroxysmal atrial fibrillation patients and in 33 normal controls. Both techniques showed increased P wave duration in patients compared with the controls (P < 0.001), but higher P wave amplitudes were obtai ned using the transesophageal technique compared with surface leads (p atients: 169.8 +/- 81.7 muV vs 15.8 +/- 7.3 muV, P < 0.0005; controls: 163.5 +/- 22.1 muV vs 18.5 +/- 5.2 muV, P < 0.0005). The signal-avera ged transesophageal lead, but not the surface recordings, identified t he presence of atrial late potentials evidenced by lower root mean squ are voltages in the terminal portion of the P wave: in last 10 seconds , 4.4 +/- 1.3 muV versus 8.5 +/- 3.0 muV, P < 0.001; in last 20 second s, 7.0 +/- 2.3 muV versus 16.0 +/- 7.9 muV, P < 0.001; in last 30 seco nds, 12.5 +/- 5.3 muV versus 23.8 +/- 12.8 muV, P < 0.001, in patients With respect to controls. The criterion P wave duration greater-than- or-equal-to 110 msec had 85% sensitivity, 100% specificity, and 100% p ositive predictive value in identifying the patients; the combined cri teria P wave duration greater-than-or-equal-to 110 msec and root mean square for the last 10 msec less-than-or-equal-to 6.5 showed 80% sensi tivity, 100% specificity, and 100% predictive value. The signal-averag ed transesophageal lead produces a higher amplitude signal, which reve als fractionation of atrial activation in atrial fibrillation and allo ws identification of individuals predisposed to this arrhythmia.