Quantitative analysis of ventricular late potentials in healthy subjects.

Signal averaging is a technique that improves the signal-to-noise ratio. Obscuring random noise, it allows the detection of low-amplitude wave forms in the terminal portion of the QRS complex, also known as ventricular late potentials. A higher incidence of arrhythmic events has been found in patients with abnormal ventricular late potentials after an acute myocardial infarction. Few studies have been conducted in healthy subjects to assess normal values. Sixty-one healthy subjects were enrolled in our study (33 men and 28 women). The results (mean +/- standard deviation) are as follows: duration of the filtered QRS (QRS duration) was 95 +/- 10 ms; duration of the low-amplitude signals in the terminal portion of QRS less than 40 microV (LAS less than 40) was 32 +/- 8 ms; and root-mean-square voltage in the last 40 ms (RMS - 40) was 33 +/- 16 microV. A significant difference was noted in QRS duration between men and women (98 +/- 11 vs 92 +/- 6 ms, p = 0.006); no difference was found in LAS less than 40 (31 +/- 8 vs 34 +/- 8 ms) and in RMS-40 (36 +/- 17 vs 30 +/- 13 microV). QRS duration confidence limits of 95% were less than or equal to 114 ms for the total group, less than or equal to 120 ms for men and less than or equal to 104 ms for women. Normalization of QRS duration for height (normal value less than 66 ms/m) eliminated any difference between men and women.(ABSTRACT TRUNCATED AT 250 WORDS)