ASSESSMENT OF CARDIAC AUTONOMIC CONTROL BY HEART PERIOD VARIABILITY IN PATIENTS WITH EARLY-ONSET FAMILIAL OBESITY

For quantitative assessment of cardiac autonomic control, time and fre quency domain measures of heart period variability were calculated by 24 h Holter recording in 10 young obese women with early-onset familia l obesity and in 10 control subjects. Ultra low frequency and very low frequency power were lower in obese subjects than in controls (P < 0. 05). High frequency power, a pure measure of vagal tone, was comparabl e between the two groups. However, low frequency power, which analysed over a 24 h Holter recording reflects parasympathetic more than sympa thetic activity, was slightly lower in obese subjects than in controls (P = 0.06). Body mass index showed an inverse correlation with total power (r = -0.62; P < 0.05) and separately with ultra low (r = -0.59; P < 0.01), very low (r = -0.64; P < 0.005), low (r = -0.61; P < 0.005) and high frequency power (r = -0.53; P < 0.05). These results demonst rate a parasympathetic withdrawal increasing body weight. The reductio n of ultra low frequency and very low frequency power, which are assoc iated with sudden death, may help to explain the higher cardiovascular risk in obesity.