Frequency analysis of the electrocardiogram with maximum entropy method for identification of patients with sustained ventricular tachycardia

The authors developed frequency analysis using the maximum entropy method (MEM) based on an autoregressive (AR) model. Orthogonal electrocardiograms were recorded from the body surface of patients with and without VT (ventricular tachycardia), and healthy persons after low noise, high-gain amplification. Multiple 40 ms segments (time intervals 2 ms, AR-parameters tapered) were analyzed (spectrotemporal mapping). Low-frequency components were eliminated by building different spectra with optimal high order and fixed low order. The MEM-spectra revealed high frequency components (40-200 Hz) in the terminal phase of the QRS-complex and in the ST-section in 26/38 patients with VT, but only in 2/20 without VT and in 1/20 healthy persons (p<0.05). Unlike FFT, MEM allowed localization of late potentials by the analysis of short data segments.