Reproducibility of the signal-averaged electrocardiogram using individual lead analysis

The aim of the study was to evaluate the immediate reproducibilityof time domain parameters in the signal averaged electrocardiogramusing a new method for endpoint determination in individualFrank leads. The method is based on a statistical model of theelectrocardiogram (ECG) in which maximum likelihood (ML) estimationis employed. The reproducibility of the ML method was comparedto that of conventional time domain analysis using the vectormagnitude (VM) of Frank leads. Fifty-nine patients were includedin the study and two consecutive ECGs were recorded for signalaveraging. The results showed that the mean of the absolutedifference of the filtered QRS duration (QRSD) between two consecutiverecordings was significantly lower for the ML method than theconventional method when employing 60 H_z highpass filtering(2.1 ± 2.2 ms vs 5.9 ± 10.2 ms, P < 0.05).Moreover, the ML method resulted in a significantly longer QRSDcompared to the VM-based method (P < 0.05). The terminalamplitude of the QRS complex (RMS40) showed a greater variabilitythan the QRSD for both methods, although the ML method was associatedwith a higher reproducibility than the VM method for the 60Hz filter. These findings may contribute to a better identificationof patients at high risk of ventricular arrhythmias. A reductionin the number of measurement errors has important implicationswhen QRS changes are analysed over time.