Detection of prior myocardial infarction patients prone to malignant ventricular arrhythmias using wavelet transform analysis.

Ventricular tachycardia (VT) and ventricular fibrillation (VF) leading to sudden cardiac death remains responsible for significant mortality in patients with prior myocardial infarction (MI). The study population consisted of 50 normal controls and 50 patients with prior MI. The MI subjects were divided into 3 groups: VT/VF (-) group; 25 patients without ventricular tachyarrhythmia, VT group; 13 patients with sustained VT, and VF group; 12 patients with resuscitated VF. The parameters on the signal-averaged ECG and the frequency components recorded from the wavelet-transformed ECG were compared. The high-frequency components (HFC; 80-150 Hz) were developed in the MI group to a greater extent than those in the control group. Among the MI patients, the HFC were more developed in the VT and VF groups than in the VT/VF (-) group. In the VF group, the positive rate of LP was 50%. Meanwhile, when the peak power value at 150 Hz > 300 was defined as abnormal, the HFC was detected in 13 (100%) patients in the VT group and 12 (91.7%) in the VF group. The sensitivity of the abnormal HFC in identifying patients with VT/VF was higher than that of SAECG (96% versus 72%), although the specificity remained similar (68.5% versus 64.3%). Abnormal HFC recorded from the wavelet-transformed ECG may be a novel factor in detecting patients who are prone to VT/VF.