Lower heart rate variability is associated with higher serum high-sensitivity C-reactive protein concentration in healthy individuals aged 46 years or more.

ABSTRACT

BACKGROUND: To test the hypothesis of an association between cardiac autonomic activity evaluated by heart rate variability and systemic inflammatory markers such as C-reactive protein, we studied the correlation of the indices of heart rate variability relative to serum high-sensitivity C-reactive protein (hs-CRP) in a healthy Brazilian population. METHODS: Four hundred twenty-one healthy individuals aged 15-82 years (mean 40.4 years), 184 men (43.7%) and 237 women (56.3%) were enrolled between July 1998 and July 2001. The relationship between the log-transformed indices of the heart rate variability and the serum concentration of hs-CRP were analyzed stratified by age tertile using the Spearman correlation coefficient and multiple linear regression. RESULTS: The log standard deviation of all normal sinus RR intervals over 24 h (SDNN) (r = -0.801; p = 0.024) was independently correlated with log hs-CRP in the individuals with age in the oldest tertile (> or = 46 years). In addition, the body mass index (BMI) was independently correlated with hs-CRP in all of the age groups. CONCLUSIONS: In the healthy subjects aged 46 years or more the lower heart rate variability correlated with higher concentration of hs-CRP.