Orthostatic Intolerance with Chronotropic Intolerance During Orthostasis in Patients with Myalgic Encephalomyelitis (Chronic Fatigue Syndrome)

21 Pages Posted: 10 Jun 2022 Publication Status: Under Review


Orthostatic intolerance markedly impairs activities of daily living in patients with myalgic encephalomyelitis (ME) or chronic fatigue syndrome. Meanwhile, chronotropic intolerance or incompetence (CI), defined as impaired chronotropic response or diminished increase in heart rate during exercise, resulting in a lower exercise capacity, may also be observed during orthostasis in patients with ME. This study reviewed the recordings of 119 patients with ME who underwent conventional active 10-min standing tests at least three times to determine CI. Among 101 adult patients (36 men and 65 women; mean age, 37±12 years), 13 experienced both tests with and without postural orthostatic tachycardia (POT) (an increase in heart rate of ≥30/min or an actual heart rate of ≥120/min) while also both success and failure in completion of standing during the 10-min. Among them, 5 (38%) experienced failure exclusively in tests without POT, while 4 (31%) had higher failure rates in tests without POT than in those with POT. Thus, CI was positive in 9 (69%) of 13 adult patients. All 18 adolescents (age <20) exhibited POT at least once, among whom 5 experienced tests with and without POT while also failure at least once. All failures except one with orthostatic hypotension were observed in the tests with POT. Thus, CI was positive in none (0%) of 5 adolescents. In conclusions, CI is common during the standing tests in adult patients with ME, suggesting impaired sympathetic activation. POT, suggesting accentuated sympathetic activation, appeared to be essential for maintaining orthostasis in such patients.

Funding Information: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors

Declaration of Interests: None.

Ethics Approval Statement: Informed consent was obtained from all study patients and this study on the conventional active 10-min standing test had been approved by the Toyama Prefectural Medical Association Ethics Committee (Approval#: 2016-010) and performed in accordance with the 1964 Declaration of Helsinki and its later amendments.

Keywords: Chronic fatigue syndrome, Myalgic encephalomyelitis, Orthostatic intolerance, Chronotropic intolerance, Postural orthostatic tachycardia

Suggested Citation

Miwa, Kunihisa, Orthostatic Intolerance with Chronotropic Intolerance During Orthostasis in Patients with Myalgic Encephalomyelitis (Chronic Fatigue Syndrome). Available at SSRN: https://ssrn.com/abstract=4132922 or http://dx.doi.org/10.2139/ssrn.4132922

Kunihisa Miwa (Contact Author)

Miwa Naika Clinic ( email )

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