Wavelet ECG Analysis in Time-Frequency Domain of the QRS-Complex in Individuals with Left Bundle Branch Block

LBBB in heart failure patients is a negative predictor for survival. This pattern is also recorded in individuals without significant structural heart diseases. The LBBB morphology has not been previously analysed using wavelet analysis in time-frequency domain in order to identify markers which distinguish these patients. The purpose of this analysis is to investigate if there are any differences in LBBB morphology between normal individuals with LBBB and patients with heart failure and LBBB. Signal-averaged electrocardiograms were recorded, in orthogonal leads and QRS decomposition in nine (9) time-frequency segments was performed using the ‘cmor’ wavelet transformation. Seventy (70) patients (mean age 66, 47 male) were studied. The mean and maximum energies of the QRS complexes were calculated in each of the 9 time-frequency segment. Wavelet parameters of the QRS complex in all segments were higher for normal individuals without LBBB. In the Z lead, the differences in mean QRS energies are significant between the two groups especially in the high frequency band (150–200 Hz) in all time segment whereas the mean energy in X lead presents significant difference in median frequency band (100–150 Hz) in the first time segment. In conclusion wavelet transformation of the QRS complex could differentiate normal individuals from heart failure patients with LBBB.