Signal Averaging of the Surface QRS Complex: Practical Applications

Signal‐Averaged ECG. Signal averaging of the surface QRS complex has been used in recent years to detect electrical signals of small amplitude not otherwise evident on the surface ECG. The technique enables detection of low‐amplitude signals in the terminal portion of the QRS complex and the ST segment. These low‐amplitude signals termed late potentials (LPs) have been correlated with the presence of fragmented electrical activity recorded from endocardial and epicardial sites due to inhomogeneous propagation of conduction in scarred myocardium. Recent studies have supported the value of the signal‐averaged ECG for risk stratification postmyocardial infarction, in the management of patients with syncope and patients with sustained ventricular tachycardia (VT), and survivors of cardiac arrest.