Cardiac autonomic modulation and incidence of late potentials in essential hypertension: role of age, sex, ventricular mass and remodeling

The influence of age, sex, left ventricular hypertrophy (LVH) and geometry on the autonomic activity to the heart was investigated in 96 hypertensive out-patients (53 men, mean age 53 +/- 9 years) and 39 healthy subjects (19 men, mean age 43 +/- 1 years). Using 24-h Holter recordings, time [the standard deviation of all RR intervals (SDNN) and the square root of the mean of the squared differences between adjacent normal RR intervals (RMSSD)] and power spectral analysis of RR intervals [Fast Fourier algorithm, low/high frequency (LF/HF) ratio] were calculated over 24 h, daytime (D) and night-time (N) periods in all subjects. Signal averaged electro-cardiogram was recorded in 50 patients to detect late potentials. Stepwise multiple linear regression analysis showed that the 24-h LF/HF ratio was influenced by age and sex, D-LF/HF by age and N-LF/HF by sex, a higher LF/HF ratio being found in younger patients and in men. These data suggest a more prominent sympathetic modulation of cardiac activity in these groups. No differences in RR period variations were observed between patients with or without LVH. Late potentials were observed in 10 patients, and did not correlate with any of the measured parameters.