Left ventricular mass and heart rate variability in middle-aged and elderly salt-sensitive hypertensive subjects

Previous reports have shown that in salt-sensitive hypertension a high diet ary salt intake can increase sympathetic activity. We evaluated the influen ce of the autonomic nervous system on myocardial hypertrophy by power spect ral analysis of heart rate variability in middle-aged and elderly salt-sens itive hypertensive subjects. We compared autonomic nervous system activity in 32 salt-sensitive hypertensive patients (15 subjects with mean age, 42.4 +/- 2.4 years and 17 subjects with mean age, 74.6 +/- 1.6 years) and 20 ag e-matched normotensive controls. Power spectral analysis detects four spect ral components: total power (TP), high-frequency (HF), low-frequency (LF) a nd very-low-frequency (VLF) power. In the elderly subjects we found an asso ciation between the left ventricular mass index (LVMI) and the following va riables: very-low frequency (p < 0.0001), 24-h urinary sodium excretion (P < 0.0001) and diastolic blood pressure (DBP) (P < 0.0001). In contrast, in middle-aged subjects we found a significant association between the LVMI an d LF (P < 0.001). In middle-aged, but not in elderly salt-sensitive hyperte nsive subjects, increased sympathetic activity correlated with the LVMI (P < 0.0001). Our findings suggest an association between sympathetic hyperact ivity and the LVMI in middle-aged subjects with salt-sensitive hypertension . (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.