Clinical application of the signal-averaged electrocardiogram and "late potentials".

The signal-averaged ECG has proven to be a valuable tool for identifying patients at risk of ventricular arrhythmias. This computerized method of analyzing standard ECGs identifies microvolt-level late potentials that represent delayed conduction through diseased myocardium. This diseased myocardium is a potential substrate for reentrant ventricular arrhythmias. In select patient groups, the signal-averaged ECG predicts electrophysiologic testing results. Problems remain and continued development is needed to evaluate patients with conduction system disease, the patient without coronary artery disease but at risk of sudden death, and proper general application of the technique.