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Higher heart rate and reduced heart rate variability persist during sleep in chronic fatigue syndrome: a population-based study.

Boneva RS, Decker MJ, Maloney EM, Jones JF, Helgason HG, Heim C, Rye DB, Reeves WC.
Higher heart rate and reduced heart rate variability persist during sleep in chronic fatigue syndrome: a population-based study. Autonomic Neuroscience Basic and Clinical doi:10.1016/j.autneu.2007.08.002.

Summary

Many of the clinical features of CFS are similar to those among people with diseases involving the autonomic nervous system. Some studies have found abnormalities of autonomic nervous system function to be more common in people with CFS than in healthy controls and other studies have found no differences in autonomic nervous system function between CFS and controls. However, these studies have enrolled different groups of patients and have been conducted under various challenges (e.g., tilt-table, treadmill), so they cannot be compared. In this study we enrolled persons with CFS identified from the general population of Wichita and matched non-fatigued controls from the same population. We measured heart rate and heart rate variability over two nights while the participants were sleeping. We found that persons with CFS had significantly increased sleeping heart rates and significantly decreased heart rate variability (assessed by various methods) than matched non-fatigued controls. This also correlated with higher baseline norepinephrine and lower baseline aldosterone levels in the CFS group compared to the controls. These findings suggest a state of sympathetic autonomic nervous system predominance with perturbed neuroendocrine activity play a role in the pathophysiology of CFS.

Abstract

Autonomic nervous system (ANS) dysfunction has been suggested in patients with chronic fatigue syndrome (CFS). In this study, we sought to determine whether increased heart rate (HR) and reduced heart rate variability (HRV) parameters observed in CFS patients during wakefulness persist during sleep. To this end, we compared heart rate (HR) and HRVas indicators of ANS function in CFS subjects and nonfatigued (NF) controls in a population-based, case-control study. Thirty subjects with CFS and 38 NF controls, matched for age-, sex- and body mass index, were eligible for analysis. Main outcome measures included mean RR interval (RRI), HR, and HRV parameters derived from overnight ECG. Plasma aldosterone and norepinephrine levels, medicines with cardiovascular effect, and reported physical activity were examined as covariates. General Linear Models were used to assess significance of associations and adjust for potential confounders. Compared to controls, CFS cases had significantly higher mean HR (71.4 vs 64.8 bpm), with a shorter mean RRI [840.4 (85.3) vs 925.4(97.8) ms] ( p b 0.0004, each), and reduced low frequency (LF), very low frequency (VLF), and total power (TP) of HRV ( p b 0.02, all). CFS cases had significantly lower plasma aldosterone ( p b 0.05), and tended to have higher plasma norepinephrine levels. HR correlated weakly with plasma norepinephrine ( r =0.23, p =0.05) and moderately with vitality and fatigue scores ( r = − 0.49 and 0.46, respectively, p b 0.0001). Limitation in moderate physical activity was strongly associated with increased HR and decreased HRV. Nevertheless, among 42 subjects with similar physical activity limitations, CFS cases still had higher HR (71.8 bpm) than respective controls (64.9 bpm), p =0.023, suggesting that reduced physical activity could not fully explain CFS-associated differences in HR and HRV. After adjusting for potential confounders case-control differences in HR and TP remained significant ( p b 0.05). Conclusion: the presence of increased HR and reduced HRV in CFS during sleep coupled with higher norepinephrine levels and lower plasma aldosterone suggest a state of sympathetic ANS predominance and neuroendocrine alterations. Future research on the underlying pathophysiologic mechanisms of the association is needed.

Page last modified on October 24, 2007

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