Left ventricular mass predicted by a single reading of ambulatory blood pressure in essential hypertension

The spectral power of heart rate variability has been shown to be negativel y correlated with left ventricular mass (LVM), suggesting the contribution of left ventricular hypertrophy to autonomic dysfunction in essential hyper tension. However, a simultaneous assessment of autonomic function and ambul atory blood pressure in relation to LVM has not been carried out. The objec tive of the present study was to elucidate the synergistic effects of ambul atory blood pressure and autonomic nerve activity on the heart. We enrolled 25 ambulant patients with untreated essential hypertension (9 men and 16 w omen; mean age 50.6 +/- 2.0 years). The ambulatory blood pressure and heart rate variability were simultaneously monitored every 30 min for 24 h. The spectral power of high-frequency (HF: 0.15 to 0.4 Hr) and low-frequency (LF : 0.05 to 0.15 Hz) bands were measured, and the ratio of LF to HF (LF/HF) w as calculated. LF/HF and HF were used as indexes of sympathetic and parasym pathetic activities, respectively. LVM was determined by echocardiography. Both the average daytime and nighttime systolic ambulatory blood pressures significantly correlated with the LVM index (r = 0.644, p < 0.001; and r = 0.428, p < 0.05; respectively), although there was no such correlation with the clinic blood pressures. In contrast, a single reading of ambulatory sy stolic blood pressure measured when LF/HF reached a maximum value was signi ficantly correlated with the LVM index independently of age and sex (partia l r = 0.484, p < 0.05). These results suggest that the ambulatory systolic blood pressure during increases in the activity of the sympathetic nervous system is able to infer LVM in essential hypertension.