Reduced heart rate variability predicts fatigue severity in individuals with CFS/ME. Escorihuela et al. 2019

John Mac

John Mac

Senior Member (Voting Rights)
Abstract
Background
Heart rate variability (HRV) is an objective, non-invasive tool to assessing autonomic dysfunction in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). People with CFS/ME tend to have lower HRV; however, in the literature there are only a few previous studies (most of them inconclusive) on their association with illness-related complaints. To address this issue, we assessed the value of different diurnal HRV parameters as potential biomarker in CFS/ME and also investigated the relationship between these HRV indices and self-reported symptoms in individuals with CFS/ME.

Methods
In this case–control study, 45 female patients who met the 1994 CDC/Fukuda definition for CFS/ME and 25 age- and gender-matched healthy controls underwent HRV recording-resting state tests. The intervals between consecutive heartbeats (RR) were continuously recorded over three 5-min periods. Time- and frequency-domain analyses were applied to estimate HRV variables. Demographic and clinical features, and self-reported symptom measures were also recorded.

Results
CFS/ME patients showed significantly higher scores in all symptom questionnaires (p < 0.001), decreased RR intervals (p < 0.01), and decreased HRV time- and frequency-domain parameters (p < 0.005), except for the LF/HF ratio than in the healthy controls. Overall, the correlation analysis reached significant associations between the questionnaires scores and HRV time- and frequency-domain measurements (p < 0.05). Furthermore, separate linear regression analyses showed significant relationships between self-reported fatigue symptoms and mean RR (p = 0.005), RMSSD (p = 0.0268) and HFnu indices (p = 0.0067) in CFS/ME patients, but not in healthy controls.

Conclusions
Our findings suggest that ANS dysfunction presenting as increased sympathetic hyperactivity may contribute to fatigue severity in individuals with ME/CFS. Further studies comparing short- and long-term HRV recording and self-reported outcome measures with previous studies in larger CFS/ME cohorts are urgently warranted.
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https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-019-02184-z
 
I posted on another thread about research and HR. I've had the kit to trace HR for 6 weeks now. Results are amazing. When at worst my HR is rock bottom. Nothing I do raises it much. When I'm feeling better HR can go sky high.

Polar training load index is always sky high 36 - 48 hours after exertion.

Strongly believe that proper small scale testing will prove real life results. Not solve ME but will go a long way in persuading GP like mine that something is wrong. Arguments with the BPS lobby would be completely unnecessary if more effort was made to prove studies like this were correct. I know my heart rate isn't functioning properly. Moaning at GP's like mine doesn't wash abnormal HR figures would.
 
Regarding heart rate variability...

I discovered info on HRV for the first time very recently and was surprised about it. I had got completely the wrong end of the stick about it in relation to health. I had assumed that a healthy heart would maintain a healthy heart rate more of the time than an unhealthy heart. And I assumed a healthy heart rate was more or less permanently around 60 - 100.

But now I realise I got that completely wrong and that a healthy heart, beating throughout an average day for a healthy person doing averagely energetic activity, could well have a heart rate that varies from quite slow to very fast at various times of day depending on demand. And that a healthy heart will get fast as activity demands it more easily than an unhealthy heart.

I feel quite embarrassed about not having thought this subject through many years ago.
 
Barry said:
Need to know of course if ME/CFS is unique in this regard, or whether other illnesses can provoke lower HRV with a similar signature.
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Indeed.

& what would help our case even more is a comparison with otherwise healthy but significantly deconditioned individuals (assuming there was a difference of course!)
 
Heart rate variability is a specific measure that analyses details about the time interval between individual heart beats and how this varies while the person is resting.

It's not about the variation in heart rate over the course of the day, or while doing different activities.

You can't calculate HRV from something like a wrist worn Fitbit, because it averages the intervals over short periods as number of beats per minute, it doesn't record the interval between consecutive beats.

Here's an article about it:
An Overview of Heart Rate Variability Metrics and Norms
Heart rate is the number of heartbeats per minute. Heart rate variability (HRV) is the fluctuation in the time intervals between adjacent heartbeats (1). HRV indexes neurocardiac function and is generated by heart-brain interactions and dynamic non-linear autonomic nervous system (ANS) processes.
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Trish said:
Heart rate variability is a specific measure that analyses details about the time interval between individual heart beats and how this varies while the person is resting.

It's not about the variation in heart rate over the course of the day, or while doing different activities.

You can't calculate HRV from something like a wrist worn Fitbit, because it averages the intervals over short periods as number of beats per minute, it doesn't record the interval between consecutive beats.

Here's an article about it:
An Overview of Heart Rate Variability Metrics and Norms
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Thanks, Trish. I obviously still have much to learn on this subject. :)
 
Speaking for myself, It was very interesting to experience how HRV would rise by doing simple things such as slow breathing for a couple of minutes. I was able to track the pattern of the increased Sympathetic activity which would increase after every crash i had. Many crashes one after another would signify more issues of increases in sympathetic activity. I can now immediately tell when my sympathetic activity is increased :I feel Bloated, i cannot digest food and have loss of appetite.
 
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Trish said:
I wonder whether there is research on HRV in patients with anxiety or depression.
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Two examples:


I haven't really looked into this, but from briefly scanning articles I suspect that HRV is just an indicator of ill health/fitness and that being sedentary and deconditioned will also result in reduced HRV.


It would be more interesting if there was a specific pattern in the HRV. One bit in this paper that caught my intention was:
this study reveals a relationship of two HRV indices (RMSSD and HFnu) with fatigue symptoms; that is, low values of RMSSD (obtained from time domain HRV analysis) and low values of HFnu (obtained from frequency domain analysis) are specifcally associated with high fatigue symptoms (as assessed by overall FIS-40 score) in the CFS/ME patients, but not in healthy controls. As this relationship did not appear between other HRV variables and other self-reported measures scores, we believe that this is the frst evidence of an association between HRV changes and outcome measures in CFS/ME.
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But one would have to compare ME/CFS patients to other patient groups to find something like that.
 
Low HRV is an indicator of a lot of things. AFAICT it drops whenever you're under any kind of stress, including allergies or insomnia. It's not particularly surprising that an increase in physical symptoms in ME/CFS would correlate with a change in HRV. FWIW I found that my HRV increased during a particular crash last year, and it certainly wasn't correlated with an improvement in health.

It's an interesting idea to see if there's anything specific to ME/CFS that can be detected, I suppose. But if they're only looking at "people who have stuff wrong with them" and "people who don't have stuff wrong with them", then I don't see what the measurement is going to usefully tell us.
 
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At the risk of sounding like a BPS proponent here, "it's deconditioning!" seems to be the appropriate response. More symptoms = increase probability of sedentary lifestyle = lower HRV. I don't see anything here that indicates ME/CFS patients have any difference in HRV from somebody who walks an equally few number of steps per day.
 
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