Heart Problems in Chronic Fatigue Syndrome

Cardiac abnormalities linked to unexplained fatigue

Thierry Dosogne

Chronic fatigue syndrome (CFS) — also referred to as myalgic encephalopathy, or ME/CFS — is a medical condition characterized by persistent fatigue and other symptoms which limit a person's ability to carry out normal, everyday tasks. ME/CFS is not well understood and is believed to be caused by a combination of psychological, genetic, and biological factors.

In recent years, researchers have noticed that, in addition to the symptoms of exhaustion, people with ME/CFS have higher rates of heart abnormalities than the general population.

While it is often difficult to connect cause with effect, there are many in the research community who believe that this association is more than incidental.

Types of Heart Abnormalities

One foundational study conducted in 2006 reported that persons with ME/CFS who died of heart failure did so at a mean age of 58.7 years compared to 83.7 years for those without ME/CFS. While no one can know for sure which factors may have contributed to this result, studies like this have long suggested that ME/CFS is inherently linked to insufficient heart function.

And the abnormalities don't stop there. Other investigators have noted similar high rates of heart irregularities, including:

  • a lack of nocturnal heart rate variability (meaning the heart fails to slow as expected during sleep)
  • a small left ventricle (the chamber of the heart that pumps blood to the rest of the body)
  • postural tachycardia (a condition where the heart rate speed up, often unevenly, when a person rises)
  • short QT interval (a genetic disorder which affects the electrical system of the heart and causes palpitations or sudden loss of consciousness)
  • abnormally low blood volumes

These irregularities may, in fact, explain some of the key symptoms of ME/CFS. They also suggest that people living with ME/CFS may need to work harder to maintain good heart health than persons in the general population.

Low Heart Rate Variability

A study conducted in 2011 looked into sleep patterns in people with ME/CFS in order to better understand why unrefreshing sleep is commonly reported in this group. What they found, surprisingly, was that people with ME/CFS had little variation in their heart rate from day to night, a condition known as low heart rate variability (HRV).

To understand this, if you feel your pulse and then breathe in and out slowly, you'll notice that your heart rate changes slightly, speeding up when you breathe in and slowing down when you breathe out. That's heart rate variability.

A low nocturnal HRV suggests that there's a problem with the nerve signals that regulate the pacemaker of the heart (called the sinus node). This is in line with thinking that ME/CFS may be caused, at least in part, by flaws in a person's autonomic nervous system (the system which regulates involuntary functions such as breathing, digestion, and heart rate).

Small Left Ventricle

A 2011 study found that some people with ME/CFS have a smaller left ventricle, the chamber of the heart responsible for pumping blood to the rest of the body. As a result of this, persons will invariably experience symptoms of what is called orthostatic intolerance (OI).

Normally, when we get up from a seated or lying position, our blood pressure will rise briefly to counter gravity and keep the blood flowing to the brain. With OI, this doesn't happen, and a person will end up feeling dizzy or fainting whenever he or she rises. This physiological anomaly could explain why minimal exertion tends to wear out a person with ME/CFS more than others.

Postural Tachycardia

Postural tachycardia is similar to OI except that it involves the pulse rate rather than the blood pressure. Tachycardia is the medical term for an abnormally rapid heart rate. Postural tachycardia simply means your heart rate speeds up abnormally whenever you rise, resulting in dizziness or even fainting.

Postural tachycardia is commonly seen in people with ME/CFS, running at three times the rate of the general population.

Short QT Interval

A QT interval is a term used to describe the space between certain up-and-down beats on an electrocardiogram (ECG) ​readout. A short QT interval means that your heart is beating normally but has less chance to recover after a heartbeat. A short QT interval is typically considered a genetic disorder and is associated with the increased risk of sudden cardiac death. While rare in the general population, a short QT interval is frequently seen in persons with ME/CFS.

Abnormally Low Blood Volume

Two studies conducted in 2009 and 2010 reported that persons with ME/CFS had lower blood volumes than the general population. Moreover, the severity of ME/CFS directly corresponded with a decrease in blood volume, meaning those who were less able to function had far less blood than those who were. Many scientists now believe that low blood volume contributes to many of the symptoms of ME/CFS simply by depriving cells of the oxygen needed to produce energy.

What the Research Tells Us

While the studies suggest that abnormalities of the heart and nervous system contribute to the high rates of cardiac failure in people with ME/CFS, they shouldn't suggest that they are the only factors. Other things, such as weight and sedentary lifestyle, may contribute as much or even more.

In the end, most of these studies are small and isolated and need far more investigation to considered conclusive. What they should highlight, however, is the increased need to monitor the cardiac health of people living with ME/CFS. This is especially true for those with severe symptoms as well as anyone who has risk factors for cardiac disease (including smoking, obesity, and a lack of exercise).

What is becoming increasingly clear is that ME/CFS is not "all in your head." If living with ME/CFS, treat it as would any other medical condition by looking not only at the illness itself but at its impacts on your overall good health.


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