What is Epicardial Fat and How Can it Hurt Your Heart

You’ve probably heard that carrying excess fat around your midsection is more dangerous than carrying fat elsewhere in the body. But did you know that those who carry extra weight around the abdomen are also more likely to have it around the heart? And this is extremely dangerous. 

While a small amount of fat around the heart protects and supports it, individuals with higher amounts of this epicardial adipose tissue (EAT) are at a much higher risk of developing heart disease, atrial fibrillation, or having a catastrophic cardiac event.  

Understanding fat

When thinking of fat, most people imagine a clump of squishy tissue stored under the skin. However, fat is much more than passive tissue that serves as a storage compartment. Instead, it’s a complex, living organ that influences many functions in the body. 

While fat is generally considered undesirable, some essential functions of fat in the human body exist. For example, fat stores energy, helps absorb vitamins, protects our organs, and keeps us warm. However, in excess, fat is one of the biggest killers. 

There are two primary types of body fat: 

  • Subcutaneous fat

Also known as “soft fat,” subcutaneous fat is found just underneath the skin. Subcutaneous fat is the fat that can be pinched between the fingers.

  • Visceral fat

Visceral fat is the “hidden fat” that wraps around organs in the abdominal cavity. This metabolically active “organ” releases hormones and proteins that contribute to inflammation in the body. 

What is epicardial fat?

One place where visceral fat can accumulate is around the heart. Epicardial fat refers to the fat deposits that exist on the surface of the heart, between the sac that surrounds the heart (pericardium) and the heart itself. 

This fat directly touches the heart and the major coronary arteries covering it. In addition, epicardial fat and the heart muscle share the same coronary blood flow, thus influencing one another. Both visceral and epicardial fat derive from brown adipose tissue. 

Medical experts estimate that epicardial fat covers 80 percent of the heart’s surface and constitutes 20 percent of heart weight. Epicardial fat more commonly accumulates over the right ventricle. 

You may wonder why there might be fat around the heart. A degree of epicardial fat is normal in the body. Epicardial adipose tissue is made of active free fatty acids, which play an essential role in the heart’s metabolism. In addition, it:

  • Protects the coronary arteries from tension or torsion
  • Keeps the heart at a healthy temperature
  • Provides an energy source for the heart muscle itself 
  • Plays a neurological role in the cardiac nervous system
  • May help to modulate cardiac function 
  • Secretes anti-inflammatory cytokines that influence blood clotting, arterial wall function, and inflammation. 

Epicardial fat often increases with age, obesity, and diabetes. It also seems to impact females at a higher rate than males. 

The downsides of epicardial fat

While this fat serves an important role in heart function, too much of it can prove deadly. As we age, the role of epicardial fat changes from being more protective to more pathological. Excess epicardial fat has been linked to multiple cardiovascular conditions, including: 

Coronary artery disease 

Over the last few decades, multiple studies have linked epicardial adipose tissue with coronary artery disease. This is because excess fat around the heart secretes proinflammatory cytokines, promoting plaque development. 

A recent 2022 study found that excess fat around the heart causes the coronary arteries to narrow, increasing the risk of coronary artery disease. 

Heart failure 

Research shows that excess epicardial fat increases the risk of heart failure. Moreover, studies have found that epicardial adipose tissue contributes to higher rates of hospitalization and death for patients with heart failure. 

Atrial fibrillation

A growing body of evidence demonstrates that epicardial fat is linked to the development of atrial fibrillation. Studies also show that fat around the heart impacts the severity and recurrence of AFib. 

There are many reasons why epicardial fat may contribute to AFib. For example, one study found that individuals with a fatty heart had increased scarring in the left atrium, triggering AFib. It may also promote AFib due to oxidative stress, fatty infiltration of the heart, and other proinflammatory causes. 

A recent 2022 meta-analysis including nearly 2,000 AFib patients concluded that individuals with excess epicardial fat had a much higher chance that their AFib would return after catheter ablation. As such, those with AFib can potentially reduce their risk of having it come back by lowering their epicardial fat.

Beyond the cardiac conditions listed above, individuals with too much epicardial fat also are at risk for metabolic syndrome. Metabolic syndrome is a collection of risk factors that increase the odds of developing heart disease, stroke, and diabetes. 

Studies have found that too much epicardial fat is associated with type 2 diabetes, high blood pressure, and obesity. Recent studies have even found that epicardial fat may contribute to Covid-19 severity.

How much is too much? 

As noted earlier, a small amount of this fat is normal. However, too much is dangerous. But how much is too much? 

Epicardial fat is measured by its thickness in specific locations around the heart. Unfortunately, no defined value is considered normal for epicardial adipose tissue thickness. As a general rule, doctors begin to worry if it is greater than 5 millimeters, or the size of a pencil eraser. 

How do I know if I have too much epicardial fat? 

A fatty heart is not generally something that can be felt. Therefore, many wonder how they might know if they have too much epicardial fat. 

Multiple studies have found a correlation between abdominal subcutaneous fat and visceral fat. In other words, the larger the waist circumference, the higher the risk of fat around the organs. Studies have also found that epicardial thickness is associated with abdominal visceral fat thickness, especially in those who are obese. 

As a result, one of the easiest and most cost-effective ways to predict epicardial fat is to examine body mass index (BMI) and waist circumference. Individuals with a BMI greater than 25 have a higher chance of having epicardial fat. Additionally, men with a waist circumference of more than 40 inches, and women with more than 35 inches, are more likely to have too much fat around the heart.

However, even seemingly healthy individuals of average weight can have hidden epicardial fat. As a result, cardiologists sometimes measure epicardial adipose tissue using cardiac imaging. 

The most commonly used imaging for heart fat is transthoracic echocardiography, or TTE. This non-invasive procedure uses a small transducer that takes an ultrasound of the heart. An MRI and CT scan can also measure epicardial fat thickness. 

Can epicardial fat be reduced?

Epicardial fat absolutely can, and should, be lowered whenever possible. Many doctors often prescribe medication to help reduce the risk factors that lead to excess epicardial fat. For example, they may suggest drugs to reduce blood sugar or cholesterol, hoping to reduce fat thickness around the heart. However, these medications have multiple side effects and are rarely proven effective in lowering this fat.

Changing poor lifestyle habits is the only reliable and safe way to reduce epicardial adipose tissue. Exercise is one of the best things for heart health. Studies have found that cardiovascular and resistance training help reduce epicardial fat. However, resistance strength training is most beneficial in reducing heart fat. 

Moreover, eating a whole-food-based organic diet is imperative in controlling how much fat accumulates around the heart. Studies show that a healthy diet lowers epicardial fat, thus reducing the risk of heart-related disease. 

For example, a 2022 study evaluated the effect that eating a healthy diet had on 199 AFib patients who underwent an ablation. Researchers concluded that individuals who ate a diet rich in fish, vegetables, nuts, seeds, and healthy fats had less epicardial fat. Moreover, these patients had a significantly lower risk of AFib recurrence after the ablation. 

Next Steps

The concern about epicardial fat is that many people have no idea how much fat accumulates around their hearts. Even those deemed “skinny” may have thickened epicardial adipose tissue. 

If you are worried about a fatty heart, consider a complementary call with one of our experienced health coaches. Together, you can determine your risk. From there, you can map a path to your 100 Year Heart. 

Eat well, Live well, Think well


Medical Review: Lauren Lattanza NMD 2022

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