A cardiac mapping system for identifying late potentials: correlation with signal averaged surface recordings

Cardiac late potentials, measured with the signal-averaged ECG, have been strongly correlated with potentially lethal ventricular arrhythmias. A key factor in identifying and quantifying these late potentials is the determination of the end of ventricular depolarization. The goal of this study was to identify the latest moment of ventricular depolarization by comparing a signal-averaged ECG with multielectrode cardiac mapping of infarct regions. The four-day-old, canine myocardial infarction model was used. In 10 of 13 dogs studied, a concordance in timing between the epicardial array and signal-averaged XYZ surface leads was found. In three dogs the lack of concordance is attributed to a poor signal-to-noise ratio of the surface-signal average and its distortion by high-pass filtering, which often eliminates enough signal energy to preclude identification. Further improvements in low-level signal recovery and postaveraging analysis are needed to ensure that cardiac late potentials are fully identified from body-surface recordings