Evaluation of myocardial damage in chagasic patients from the signal-averaged and beat-to beat analysis of the high resolution electrocardiogram

The aim of this work was to compare the results of the signal-averaged and beat-to-beat analysis of the high resolution electrocardiogram (HRECG) of 96 chronic chagasic patients classified in different groups (I, II and III) according to their degree of myocardial damage. For comparison, the HRECGs of 11 healthy subjects used as control group (Group O) were also examined. In the signal-averaged analysis, three standard indexes were computed from the vector magnitude of the filtered and averaged XYZ leads: (a) the QRS duration (QRSD); (b) the RMS voltage of the terminal 40 ms (RMS40) and (c) the duration of the terminal low amplitude signal below 40 muV (LAS40). In the beat-to-beat analysis, the variability of the QRS duration (DeltaQRSD) was calculated. It has been found that two or more indexes exhibited statistical differences (p<0.05) between groups O-II, O-III, I-II, I-III and II-III. We concluded that the signal-averaged and beat-to-beat analysis of HRECG is a promising diagnosis technique to evaluate the degree of myocardial damage in chronic chagasic patients.