Evidence of altered cardiac autonomic regulation in myalgic encephalomyelitis/chronic fatigue syndrome: A systematic review and meta-analysis.

ABSTRACT

BACKGROUND: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex condition with no reliable diagnostic biomarkers. Studies have shown evidence of autonomic dysfunction in patients with ME/CFS, but results have been equivocal. Heart rate (HR) parameters can reflect changes in autonomic function in healthy individuals; however, this has not been thoroughly evaluated in ME/CFS. METHODS: A systematic database search for case-control literature was performed. Meta-analysis was performed to determine differences in HR parameters between ME/CFS patients and controls. RESULTS: Sixty-four articles were included in the systematic review. HR parameters assessed in ME/CFS patients and controls were grouped into ten categories resting HR (RHR), maximal HR (HRmax), HR during submaximal exercise, HR response to head-up tilt testing (HRtilt), resting HR variability (HRVrest), HR variability during head-up tilt testing (HRVtilt), orthostatic HR response (HROR), HR during mental task(s) (HRmentaltask), daily average HR (HRdailyaverage), and HR recovery (HRR) Meta-analysis revealed RHR (MD ±â€Š95% CI = 4.14 ±â€Š1.38, P < .001), HRtilt (SMD ±â€Š95% CI = 0.92 ±â€Š0.24, P < .001), HROR (0.50 ±â€Š0.27, P < .001), and the ratio of low frequency power to high frequency power of HRVrest (0.39 ±â€Š0.22, P < .001) were higher in ME/CFS patients compared to controls, while HRmax (MD ±â€Š95% CI = -13.81 ±â€Š4.15, P < .001), HR at anaerobic threshold (SMD ±â€Š95% CI = -0.44 ±â€Š0.30, P = 0.005) and the high frequency portion of HRVrest (-0.34 ±â€Š0.22, P = .002) were lower in ME/CFS patients. CONCLUSIONS: The differences in HR parameters identified by the meta-analysis indicate that ME/CFS patients have altered autonomic cardiac regulation when compared to healthy controls. These alterations in HR parameters may be symptomatic of the condition.