Combined Use of Time and Frequency Domain Variables in Signal-Averaged ECG as a Predictor of Inducible Sustained Monomorphic

Background. Time and frequency domain analyses of signal-averaged ECG (SAECG) have several individual limitations, and the results of the two methods sometimes vary considerably. The purpose of this study was to determine whether the combined use of time and frequency domain variables facilitates identification of patients who will have ventricular tachycardia (VT) induced during programmed ventricular stimulation (PVS). Methods and Results. Nine myocardial infarction (MI) patients with clinically documented sustained monomorphic VT (SMVT), 40 MI patients without clinical VT, and 30 normal healthy control subjects were evaluated. PVS using three extrastimuli and SAECG recording were performed in the MI patients on day 36±4 after infarction. Of 40 MI patients, SMVT was inducible in 14, sustained polymorphic VT in three, nonsustained monomorphic VT in three, nonsustained polymorphic VT in two, and no inducible arrhythmia was obtained in 18. There were significant differences between MI patients with inducibl