State of the Current Science and Future Directions
Because ME/CFS is diagnosed based on clinical criteria, it is a syndrome that, much like congestive heart failure, will be shown to have multiple causes (Central Illustration). A reviewer of this paper suggested that chronic conditions limiting activity (widespread pain or sleeplessness) might be expected to produce severe fatigue and perhaps OI. That reviewer suggested that longitudinal studies be performed on younger patients with ME/CFS to determine whether the cardiac changes reported here do or do not occur in the less symptomatic patient and what happens to any cardiovascular abnormalities as the illness waxes and wanes over time. Only crosssectional studies have been done to date. The results from such a longitudinal study might eliminate some of the confounds in our current knowledge base.
Symptomatic Schematic of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome
A symptomatic schematic of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). POTS = postural orthostatic tachycardia syndrome; PTSD = post-traumatic stress disorder; SV = stroke volume.
The lack of biomarkers or organ pathology has led to the interpretation that ME/CFS could be a somatic manifestation of psychiatric diagnoses such as anxiety or major depression. However, the organic basis for most cases of ME/CFS is supported by what we are seeing today during the coronavirus disease-2019 (COVID-19) pandemic. A report on survivors of the 2003 SARS pandemic noted that 27% fulfilled 1994 case criteria for ME/CFS. Consistent with that report, we are currently seeing many patients who were relatively mildly affected by acute COVID-19 infection but who now report symptoms consistent with the diagnosis of ME/CFS; many of these patients also have physiological manifestations of OI. Comparing the post–COVID-19 patient with ME/CFS to the ME/CFS patient whose illness is not associated with COVID-19 infection should help us better understand the pathophysiology of both.
J Am Coll Cardiol. 2021;78(10):1056-1067. © 2021 American College of Cardiology Foundation