Evaluation of Arrhythmogenic Substrate in Patients With Hypertrophic Cardiomyopathy Using Wavelet Transform Analysis

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is thought to have a microvolt-level electrical disarrangement in the myocardium that leads to ventricular tachyarrhythmias and sudden cardiac death. Although signal-averaged electrocardiography (ECG) has been used to detect late potential as a parameter of electrical instability, its predictability is not high. The focus of the present study was the ability of high-resolution wavelet transform from beat-to-beat analysis to detect arrhythmogenic substrates and to evaluate its relationship to the severity of ventricular tachycardia. METHODS AND RESULTS: The study group comprised 50 healthy subjects and 50 patients with HCM. The filtered-QRS duration from the signal-averaged ECG, the high-power duration (HPD) and number of disarrangement points (NDP) from the wavelet-transform ECG were measured. When HPD was defined >114 ms and/or NDP >9 points as abnormal, the sensitivity and specificity for ventricular tachycardia was 93.8% and 79.4%, respectively. When a mean +/- standard deviation of the HPD in normal subjects was defined as normal, 93.8% of patients with a positive late potential were out of the normal range. CONCLUSIONS: The newly developed color-display 3-dimensional wavelet transform system showed good time-frequency resolution in analyzing every single beat without signal-averaging. The analysis could be used to detect arrhythmogenic substrates in patients with HCM.