An electrocardiographic study, usually performed on patients with unexplained loss of consciousness or suspected dysrhythmias, in which hundreds of QRS complexes are collected, filtered, and analyzed to discover the presence or absence of certain abnormalities in the conducting system of the ventricle. These abnormalities, called late potentials, point to an increased risk of ventricular tachycardia or ventricular fibrillation. The signal-averaging technique allows late potentials to be examined free from random electrical discharges (“noise”), which often are present when only a small number of QRS complexes are evaluated.