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 technique and a transesophageal lead technique were performed in 45 idiopathic 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 obtained using the transesophageal technique compared with surface leads (patients: 169.8 ± 81.7 μV vs 15.8 ± 7.3 μV; P < 0.0005; controls: 163.5 ± 22.1 μV vs 18.5 ± 5.2 μV; P < 0.0005). The signal-averaged transesophageal lead, but not the surface recordings, identified the presence of atrial late potentials evidenced by lower root wean square voltages in the terminal portion of the P wave: in last 10 seconds, 4.4 ±1.3 μV versus 8.5 ± 3.0 μV; P < 0.001; in last 20 seconds, 7.0 ± 2.3 μV versus 16.0 ± 7.9 μV; P < 0.001; in last 30 seconds, 12.5 ± 5.3 μV versus 23.8 ± 12.8 μV; P < 0.001, in patients with respect to controls. The criterion P wave duration ≥ 110 msec had 85% sensitivity. 100% specificity, and 100% positive predictive value in identifying the patients; the combined criteria P wave duration ≥ 110 msec and root mean square for the last 10 msec ≤ 6.5 showed 80% sensitivity, 100% specificity, and 100% predictive value. The signal-averaged transesophageal lead produces a higher amplitude signal, which reveals fractionation of atrial activation in atrial fibrillation and allows identification of individuals predisposed to this arrhythmia.