Abnormal signal‐averaged electrocardiogram in patients with duchenne muscular dystrophy: Comparison of time and frequency domain analyses from the signal‐averaged electrocardiogram

Abstract

The clinical significance of an abnormal signal‐averaged electrocardiogram (SA‐ECG) in time‐ and frequency‐domain analyses was assessed in patients with Duchenne muscular dystrophy (DMD). Twenty‐four DMD patients and 20 age‐matched healthy volunteers were studied. The SA‐ECG was recorded by time‐domain signal processing using the vector‐magnitude method and frequency‐domain signal processing using the fast‐Fourier transform. Abnormal SA‐ECGs were based on comparison with controls and eight abnormal SA‐ECGs were detected among 24 DMD patients, seven by frequency‐domain analysis and four by time‐domain analysis. The end‐diastolic left ventricular volume was larger in the patients with abnormal SA‐ECG than in those with normal SA‐ECG (136±32 ml vs. 77±43 ml, p<0.01). Compared with patients with normal SA‐ECGs, the DMD patients with abnormal SA‐ECGs had a lower left ventricular (LV) ejection fraction (54±6 vs. 61 ± 8%, p < 0.05), as an index of LV contractility, and less LV posterior wall velocity (46±9 mm/min vs. 62 ± 16 mm/min, p <0.01), as an index of LV relaxation. The sensitivity and specificity of frequency‐domain analysis for predicting malignant ventricular arrhythmias was 60 and 85%, respectively, compared with 30 and 92%, respectively, for time‐domain analysis. The combination of time‐ and frequency‐domain analyses can facilitate identification of DMD patients with ventricular tachyarrhythmias associated with depression of cardiac performance. Copyright © 1993 Wiley Periodicals, Inc.