Normal limits of high-resolution signal-averaged ECG parameters of Japanese adult men and women

Abstract

High-resolution signal-averaged electrocardiography (Hi-Res ECG) has been found useful in measuring ventricular late potentials for identifying patients prone to life-threatening ventricular arrhythmias. Several studies have reported cut-off values (normal limits) of Hi-Res ECG parameters, including sex-specific limits, for adult population. However, there are no such studies reporting such limits in the Japanese population. Hi-Res ECGs were recorded from 482 normal healthy patients (204 men; 278 women) with no cardiac disease and normal electrocardiogram. Three Hi-Res ECG parameters filtered QRS duration (FQRSD), low amplitude signal duration under 40 μV of terminal QRS (LASD), and root mean square voltage in the terminal 40 milliseconds (RMSV) were analyzed. FQRSD was longer in men than in women (P<.0001). RMSV was larger in men than in women (P<.0001). There was no significant difference in LASD between men and women. The upper limit (90th percentile) of FQRSD was 116 milliseconds for women. The upper limit of LASD was 42 milliseconds for both men and women. The lower limit (10th percentile) of the RMSV was 14 μV for both men and women. There was no significant difference in the distributions of the Hi-Res ECG parameters between our study and an earlier study on mostly whites from the United States and Europe. The upper limits (90th percentile) of FQRSD and LASD in the Japanese normal patients were nearly the same as for whites. But, the lower limit (10th percentile) of RMSV in our Japanese normals was significantly smaller than that for whites. Therefore, it may be necessary to use race-specific normal limits for late potential analysis. Criteria for abnormal late potentials (defined as abnormal values in at least 2 of the 3 Hi-Res ECG parameters) were met in 18 of 482 (3.7%) normal healthy patients. Further studies are needed to evaluate the role of these criteria in identifying cardiac patients with life-threatening arrhythmias in the Japanese population.