Critical noise level reduction for correct identification of late potentials: an illustrative case report.

The precision of detection of late potentials (LPs) on signal-averaged electrocardiography (SAECG) depends on the degree of noise reduction. The recommended low-noise endpoint is 0.3 microV. We describe a patient with sustained ventricular tachycardia after myocardial infarction with very low amplitude LPs in whom a noise level lower than 0.3 microV was necessary in order to obtain an abnormal result of the SAECG. The presence of LPs was confirmed by spectral temporal mapping of the SAECG.