Signal-averaged electrocardiography (SAECG) is a special electrocardiographic technique, in which multiple electric signals from the heart are averaged to remove interference and reveal small variations in the QRS complex, usually the so-called "late potentials".

Unlike standard basal ECG recording, which requires only a few seconds, SAECG recording requires a few minutes (usually about 7-10 minutes), as the machine must record multiple subsequent QRS potentials to remove interference due to skeletal muscle and to obtain a statistically significant average trace.

SAECG recording yields a single, averaged QRS potential, usually printed in a much larger scale than standard ECGs, upon which the SAECG software performs calculations to reveal small variations (typically 1-25 uV) in the final portion of the QRS complex (the so-called "late potentials, or more accurately, "late ventricular potentials").

Late potentials are taken to represent delayed and fragmented depolarisation of the ventricular myocardium, which may be the substrate for a micro-re-entry mechanism, implying a higher risk of potentially dangerous ventricular tachyarrhythmias.

This has been used for the risk stratification of sudden cardiac death in people who have had a myocardial infarction, as well as in people with known coronary heart disease, cardiomyopathies, or unexplained syncope.