Detection of wavelet transform-processed ventricular late potentials and approximate entropy

Ventricular late potentials (VLPs) are low-level high-frequency signals that are usually found within the terminal part of the QRS complex from patients after myocardial infarction. Patients with VLPs are at risk of developing ventricular tachycardia, which is the major cause of death of patients suffering from heart disease. In this study, the continuous wavelet transform was used to detect VLPs and then approximate entropy (ApEn) was applied to classify subjects with and without VLPs. Approximate entropy has been recently proposed to quantify the irregularity in physiological signals. High ApEn values indicate greater irregularity. Patients with VLPs tend to have higher ApEn values than those without. Preliminary investigations in this study show promising results for distinction between the two patient groups.