Signal-Averaged Electrocardiography in Patients with Advanced Heart Failure: A Better Indicator of Left Ventricular Enlargement Compared with Conventional Electrocardiography

The signal-averaged electrocardiography is a noninvasive method to evaluate the presence of the potentials generated by tissues activated later than their usual timing in the cardiac cycle. The purpose of this study was to demonstrate the correlation between the filtered QRS duration obtained via the signal-averaged electrocardiography and left ventricular dimensions and volumes and then to compare it with the standard electrocardiography. We included patients with advanced systolic left ventricular dysfunction (ejection fraction ≤ 35%). All the patients underwent surface twelve-lead electrocardiography, signal-averaged electrocardiography, and echocardiography. The study included 86 patients with a mean age of 54.66 ± 13.23 years. The mean left ventricular ejection fraction was 18.31 ± 5.49%; the mean QRS duration was 0.14 ± 0.02 sec; and 52% of the patients had left bundle branch block. The mean filtered QRS duration was 145.87 ± 24.89 ms. Our data showed a significant linear relation between the filtered QRS duration and left ventricular end-systolic volume, left ventricular end-diastolic volume, left ventricular end-systolic diameter, and left ventricular end-diastolic diameter; the correlation coefficient was, however, not good. There was no significant correlation between the QRS duration and left ventricular diameters and volumes. The filtered QRS duration has a better correlation with left ventricular dimensions and volumes than does the QRS duration in the standard electrocardiography.