Is Heart Disease Part of Chronic Fatigue Syndrome?

Cardiac abnormalities linked to ME/CFS

Doctor studying ECG chart

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Chronic fatigue syndrome (ME/CFS) involves a lot more than fatigue. On top of a few dozen possible symptoms, this disease is also linked to certain heart abnormalities. Does that mean you have to worry about developing heart disease? Not necessarily. However, they do point to the need to watch out for it.

We're not sure about the cause and effect relationship of ME/CFS and heart abnormalities. We do know that the incident rate is higher in people with it than in the general population, and many researchers believe the association is more than incidental.

Types of Heart Abnormalities

One study published in the journal Fatigue in 2016 reported a mean age of 58.8 years for deaths related to heart failure in people with ME/CFS. That's about 25 years younger than the mean age of cardiac-related death overall. 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 than others to maintain good heart health.

Low Heart Rate Variability

A study conducted in 2011 looked into sleep patterns in people with ME/CFS in order to better understand the common symptom of unrefreshing sleep. 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, feel your pulse and then breathe in and out slowly. You'll notice that your heart rate changes slightly, faster when you breathe in and slower when you breathe out. That's heart rate variability.

A low night-time HRV suggests that there's a problem with the nerve signals that regulate the heart's natural pacemaker (called the sinus node). This is in line with the theory that ME/CFS is caused, at least in part, by flaws in the autonomic nervous system, which regulates automatic functions such as breathing, digestion, and heart rate.

Small Left Ventricle

Your heart has four chambers, and the ones that pump blood out to the rest of the body are called ventricles.

A 2011 study found that some people with ME/CFS have a smaller left ventricle. This is believed to explain the symptom of dizziness upon standing, which is called orthostatic intolerance (OI).

Normally, when we get up from a seated or lying position, our blood pressure will go up for just a minute to counter gravity and keep the blood flowing to the brain. When you have OI, this doesn't happen, and it makes you feel dizzy—or even faint—when you stand up.

This physiological anomaly could explain why what most people consider a small amount of exertion can wipe out someone with ME/CFS.

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, again, leading to dizziness or fainting.

Postural tachycardia is about three times more common in people with ME/CFS than in 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 more common in people with ME/CFS.

Abnormally Low Blood Volume

Two studies conducted in 2009 and 2010 reported that people with ME/CFS had lower-than-normal blood volumes–basically, less blood.

Moreover, the lower the blood volume, the more severe the case of ME/CFS. 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, that doesn't mean they're 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).

If you have ME/CFS, talk to your doctor about heart health, which of these abnormalities you may have, and what you can do to help prevent cardiac disease.

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