Key result
During tilt testing, 37% of ME/CFS patients exhibited orthostatic chronotropic incompetence, defined as an inadequate heart rate increase for a given decrease in stroke volume index.
Why the study?
ME/CFS patients have larger upright stroke volume index reductions without POTS or hypotension, raising the question of whether an incomplete compensatory heart rate increase reflects chronotropic incompetence.
Is orthostatic chronotropic incompetence present during tilt testing in ME/CFS patients compared to healthy controls?
Case-Control
Is orthostatic chronotropic incompetence present during tilt testing in ME/CFS patients compared to healthy controls?
May support targeted autonomic assessment in ME/CFS; leaves open whether absent HR compensation drives symptoms and requires prospective validation.
Background: Orthostatic intolerance (OI) is a core diagnostic criterion in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The majority of ME/CFS patients have no evidence of hypotension or postural orthostatic tachycardia syndrome (POTS) during head-up tilt, but do show a significantly larger reduction in stroke volume index (SVI) when upright compared to controls. Theoretically a reduction in SVI should be accompanied by a compensatory increase in heart rate (HR). When there is an incomplete compensatory increase in HR, this is considered chronotropic incompetence. This study explored the relationship between HR and SVI to determine whether chronotropic incompetence was present during tilt testing in ME/CFS patients. Methods: From a database of individuals who had undergone tilt testing with Doppler measurements for SVI both supine and end-tilt, we selected ME/CFS patients and healthy controls (HC) who had no evidence of POTS or hypotension during the test. To determine the relation between the HR increase and SVI decrease during the tilt test in patients, we calculated the 95% prediction intervals of this relation in HC. Chronotropic incompetence in patients was defined as a HR increase below the lower limit of the 95th % prediction interval of the HR increase in HC. Results: ; p < 0.0001) and a higher HR (87 (11) vs. 78 (15) bpm; p < 0.0001) compared to HC. There was a similar relationship between HR and SVI between ME/CFS patients and HC in the supine position. During tilt ME/CFS patients had a lower HR for a given SVI; 37% had an inadequate HR increase. Chronotropic incompetence was more common in more severely affected ME/CFS patients. Conclusion: These novel findings represent the first description of orthostatic chronotropic incompetence during tilt testing in ME/CFS patients.
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Campen et al. (2023) conducted a case-control in Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) vs. Healthy controls was evaluated on Chronotropic incompetence (inadequate heart rate increase for a given stroke volume index decrease). During tilt testing, 37% of ME/CFS patients exhibited orthostatic chronotropic incompetence, defined as an inadequate heart rate increase for a given decrease in stroke volume index.
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