Quantitative analysis of ventricular late potentials (LP) in healthy subjects. Comparative study with Holter monitoring.

Signal averaging is a technique that improves the signal-to-noise ratio. It allows the detection of low-amplitude wave formes in the terminal portion of the QRS complex, also known as ventricular late potentials. A high incidence of arrhythmic events is found in patients with abnormal ventricular late potentials after an acute myocardial infarction. Few wide studies have been conducted in healthy subjects to assess normal values. One hundred sixty-five healthy subjects are enrolled in our study (59 men and 106 women). The results (mean +/- standard deviation) are as follows: duration of filtered QRS: 89.5 +/- 9.1 ms; duration of the low-amplitude signals in the terminal portion of QRS < 40 microV: 27.1 +/- 7.8 ms; root-mean-square voltage in the last 40 ms: 47.2 +/- 29.5 microV. A signal difference is noted between men and women for the QRS duration. No difference is found in HFD40 and RMS40. QRS duration confidence limits of 95% are < 108 ms for the total group. HFD40 and RMS40 confidence limits of 95% are respectively of 43 ms and 13 microV. There is no significant difference of the values for age. There is no relation between the severity of a ventricular arrhythmia and the values of the three parameters of the late potentials in a healthy subjects population.