Research abstract:

Objectives:

To explore potential mechanisms that underpin the cardiac abnormalities seen in chronic fatigue syndrome (CFS) using non-invasive cardiac impedance, red cell mass and plasma volume measurements.

Methods

Crdiac MR (MR) examinations were performed using 3 T Philips Intera Achieva scanner (Best, NL) in participants with CFS (Fukuda; n=47) and matched case-by-case controls. Total volume (TV), red cell volume (RCV) and plasma volume (PV) measurements were performed (41 CFS and 10 controls) using the indicator dilution technique using simultaneous 51-chromium labelling of red blood cells and 125-iodine labelling of serum albumin.

Results

Te CFS group length of history (mean±SD) was 14±10 years. Patients with CFS had significantly reduced end-systolic and end-diastolic volumes together with reduced end-diastolic wall masses (all p<0.0001). Mean±SD RCV was 1565±443 mL with 26/41 (63%) having values below 95% of expected. PV was 2659±529 mL with 13/41 (32%) <95% expected. There were strong positive correlations between TV, RCV and PV and cardiac end-diastolic wall mass (all p<0.0001; r2=0.5). Increasing fatigue severity correlated negatively with lower PV (p=0.04; r2=0.2). There were no relationships between any MR or volume measurements and length of history, suggesting that deconditioning was unlikely to be the cause of these abnormalities.

Conclusions

This study confirms an association between reduced cardiac volumes and blood volume in CFS. Lack of relationship between length of disease, cardiac and plasma volumes suggests findings are not secondary to deconditioning. The relationship between plasma volume and severity of fatigue symptoms suggests a potential therapeutic target in CFS.

Key questions

What is already known about this subject?

• Chronic fatigue syndrome (CFS) has been shown to be associated with a range of cardiac abnormalities.
• Studies, to date, have suggested that these abnormalities probably arise because of deconditioning.

What does this study add?

• This study has confirmed in a large cohort that there are reductions in cardiac volume in CFS measured using cardiac MRI.
• The degree of these end-diastolic and end-systolic volume abnormalities associates with blood volume.
• The abnormalities seen are not arising secondary to deconditioning.
• Reductions in plasma volume associate with fatigue severity.

How might this impact on clinical practice?

• This study reinforces, using state-of-the art MRI, previous findings that there is a cardiac abnormality in those with CFS.
• The finding of hypovolaemia in association with cardiac structural abnormalities and fatigue severity represents a potential therapeutic target.

Reduced cardiac volumes in chronic fatigue syndrome associate with plasma volume but not length of disease: a cohort study, by Julia L Newton, Andreas Finkelmeyer, George Petrides, James Frith, Tim Hodgson, Laura Maclachlan, Guy MacGowan and Andrew M Blamire in Open Heart Vol 3, Issue 1 2016

Funded by the (UK) Medical Research Council & ME Research UK