HEART-RATE-VARIABILITY IS RELATED TO LEUKOCYTE COUNT IN MEN AND TO BLOOD LIPOPROTEINS IN WOMEN IN A HEALTHY POPULATION OF 35-YEAR-OLD SUBJECTS

Objectives. To investigate if, in a healthy randomly-selected populati on of 35-year-old men and women, there already is a relation between d ecreased heart rate variability and conventional risk factors for card iovascular disease. Background. Analysis of heart rate variability (HR V) has been used for estimating tonic autonomic activity. HRV is reduc ed in patients with various cardiovascular diseases. If a decreased HR V is a late phenomenon in the progression of cardiovascular disease, o r if it parallels or even precedes manifest disease is unknown. Design . Spectral analysis of HRV was made from 24-hour ambulatory electrocar diograms in a randomised population of healthy 35-year-old men (n = 63 ) and women (n = 70). The different spectral indices of HRV were analy sed against gender, leucocyte count (previously described as an indepe ndent risk factor for cardiovascular disease), blood lipoproteins, smo king, heredity, body mass index (BMI) and systolic blood pressure. Set ting. A research centre of general medicine and a university hospital. Results. Mean heart rate was lower, total power (TP), very low freque ncy power (VLF) and low frequency power (LF) were higher in men than i n women. In women TP, VLF and LF were negatively correlated to BMI, sm oking, triglycerides and positively correlated to HDL cholesterol. TP and VLF were also negatively correlated to risk factor score. High fre quency power (HF), a marker of parasympathetic activity, was positivel y related to HDL cholesterol. In men, at daytime, TP, VLE LF and HF we re negatively correlated to leucocyte count. TP, VLF and LF were also negatively correlated to triglycerides and VLF also to risk factor sco re. Conclusions. There are correlations between HRV and known risk fac tors for cardiovascular disease already in a healthy 35-year-old popul ation. A novel observation is the relationship in men between leucocyt e count and heart rate variability.