Background Fibromyalgia (FMS) is frequently associated with depression. Depression is a risk factor for cardiac morbidity and mortality in patients with coronary heart disease (CHD). Low heart rate variability (HRV) reflects excessive sympathetic or inadequate parasympathetic tone. Increased sympathetic or decreased parasympathetic nervous system activity predisposes patients with CHD. Little is known about whether depressive symptom in FMS is associated with reduced HRV, which is increased risk factor for CHD.

Objectives To investigate the relationship between depression and HRV in patients with fibromyalgia.

Methods We performed power spectral analysis on 5 minutes ECG in 130 patients with FMS between 24 and 73 years. All subjects have been evaluated with Korean version of the Fibromyalgia Impact Questionnaire (FIQ) and Beck Depression Inventory (BDI). BDI scores were classified as 3 groups: low (1-16, n=30), moderate (17-30, n=44) and severe (over 31, n=56). Very low frequency (VLF) power (0.0033 to 0.04 Hz) in ms², which may be influenced by sympathetic and parasympathetic inputs; low frequency (LF) power (0.04 to 0.15 Hz) in ms², which reflects both sympathetic and parasympathetic tone and is strongly associated with blood pressure regulation; and high frequency (HF) power (0.15 to 0.40 Hz) in ms², which is modulated by respiration and primarily reflects vagal tone.

Results The results of the one way ANOVA indicated that there was a difference in log-transformed High Frequency (HF) level amongst the BDI groups [F(2, 127)=3.89, p=.002]. Post-hoc comparisons using the Tukey B test indicated that severe BDI score group (3.9±1.2) has significantly lower HF level than the other BDI score groups. Low BDI score group (4.7±1.3) did not differ significantly from moderate BDI score group (4.5±1.3). There was no significant difference in VLF and LF in patients with FMS. BDI score showed negatively significant correlation with lnHF (r=-0.23, p<0.01) and partial correlation coefficient of BDI score adjusted by age was -0.21 (p=0.01).

Conclusions BDI scores in patients with FMS was negatively correlated with lnHF and the group with severe BDI scores showed significantly lower HF than the other BDI groups. Reduced vagal tone is associated with depressive symtoms in patients with FMS.

1. Carney R, Saunders R, Freedland K, Stein P, Rich M, Jaffe A. Association of depression with reduced heart rate variability in coronary artery disease. Am J Cardiol 1995;76:562-4.

2. Staud R. Heart rate variability as a biomarker of fibromyalgia syndrome. Fut Rheumatol. 2008 Oct 1;3(5):475-483.

Disclosure of Interest None Declared