[Atrial late potential (ALP) by P wave-triggered signal-averaged electrocardiogram]

Late potentials, possibly representing fractionated electrograms recorded directly from slowly conducting cardiac tissue, can be detected by signal averaged ECG (SAECG) from the body surface noninvasively. Ventricular late potential, recorded with SAECG, is a good predictor of ventricular tachyarrhythmias. Analogously, SAECG triggered by P wave has recently been proposed determining atrial late potential (ALP), possibly related paroxysmal atrial fibrillation. ALP is analyzed by the time domain or frequency domain method. In the former, the prolongation of filtered P duration is an index of ALP. The results obtained by FFT analysis in the latter are controversial, and thus additional study will be required to confirm their meaning and significance.