Cardiac Dimensions and Function Are Not Altered among Females with the Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.
Iversen, Per Ole, von Lueder, Thomas Gero, Kardel, Kristin Reimers et al. · Healthcare (Basel, Switzerland) · 2020 · DOI
Quick Summary
Researchers used heart ultrasounds to check if the hearts of people with ME/CFS were structurally different or working differently than healthy people's hearts. They found no significant differences in heart size or function between the 16 women with ME/CFS and 10 healthy women they studied. This suggests that ME/CFS exercise intolerance and lactate buildup may not be caused by problems with how the heart itself is structured or functioning.
Why It Matters
Understanding whether ME/CFS involves cardiac dysfunction is crucial for explaining exercise intolerance and abnormal lactate accumulation—hallmark features of the disease. These findings help narrow the search for the underlying cause of ME/CFS symptoms by ruling out the heart as a primary source of dysfunction, potentially redirecting research focus toward metabolic and mitochondrial mechanisms.
Observed Findings
No significant differences in cardiac chamber dimensions between ME/CFS patients and controls
No significant differences in left ventricular ejection fraction or systolic function between groups
No significant differences in diastolic function parameters between groups
No significant differences in tissue Doppler or cardiac strain variables between groups
Inferred Conclusions
Cardiac structural and functional abnormalities are not present in female ME/CFS patients in this cohort
Abnormal lactate accumulation in ME/CFS is likely not caused by primary cardiac dysfunction
The exercise intolerance and energy dysregulation in ME/CFS likely result from mechanisms outside cardiac pathology
Remaining Questions
What mechanisms are responsible for the abnormal lactate accumulation observed in ME/CFS patients if not cardiac dysfunction?
Do male ME/CFS patients show similar cardiac findings, or are there sex differences in cardiac involvement?
Could there be cardiac dysfunction detectable only during exercise stress testing rather than at rest?
What This Study Does Not Prove
This study does not prove that cardiac abnormalities never occur in ME/CFS, as it only examined a small group of 16 women and used single time-point measurements. It also does not establish what is actually causing the abnormal lactate accumulation observed in ME/CFS patients, only that structural or functional heart problems are unlikely to be the explanation. Additionally, findings in women may not generalize to men with ME/CFS.