Diurnal variation of ECG intervals and R or T amplitudes in healthy male subjects assessed by means of spectral and cosinor analysis

Abstract

Twelve lead standard ECGs 35 healthy male volunteers, recorded from 08.00 H up to 01.00 H, were analysed retrospectively in order to investigate primarily the diurnal changes in vital sign measurements, ECG interval durations (PQ, QRS, QTc) and R wave as well as T wave amplitudes. Data were analysed descriptively and by means of ANOVA, spectral analysis and cosinor models. ANOVA revealed significant variations for vital sign parameters and the QTc interval, although remarkable variation in all ECG parameters was observed. T wave amplitudes in particular showed marked alterations, with changes up to 40%. Transient maxima of median T wave amplitudes and QTc interval duration were found at 12.00 H and 14.00 H, respectively. R wave amplitudes and PQ duration revealed lower values in the afternoon. Although there was remarkable interindividual variability, ultradian rhythmic activity of ECG parameters was confirmed by spectral analysis and cosinor models based on population data.