Late potentials on the signal-averaged ECG suggesting possible substrate for reentrant ventricular arrhythmias

Signal-averaged electrocardiogram (SAECG) showing a QRS complex after a first and second myocardial infarction (MI) in the same patient. Left panel: After a first MI, no late potentials are present on the SAECG. Right panel: After a second MI, late potentials are seen as low amplitude signals at the end of the QRS complex (arrow). The filtered QRS duration is increased to >120 milliseconds.