Inflammatory Bowel Disease and Atrial Fibrillation

Is there a link between inflammatory bowel disease and atrial fibrillation?

Atrial Fibrillation (often referred to as ‘AF’) and Inflammatory Bowel Disease (also called ‘IBD’) are two conditions that you have probably heard of at some point in your life. Perhaps you or somebody you know even suffers from one of them. But have you ever thought of the two as having anything to do with one another? Recent studies are now showing that AF and IBD may indeed be linked in certain ways. But first, let's understand what these two conditions are.

What is inflammatory bowel disease?

Inflammatory Bowel Disease (IBD) is an umbrella term for two chronic conditions which cause inflammation in the digestive tract - the organs involved in digestion, stretching from your mouth to your anus. These conditions are called Crohn’s disease and ulcerative colitis. Whilst the symptoms can be helped with appropriate treatment, they are long-term diseases. 

Common symptoms of IBD

Common symptoms of IBD include:

• Stomach pain 
• Losing weight
• Fatigue 
• Bleeding from the rectum
• Blood in stools 
• Persistent diarrhoea 

Causes of IBD

The cause of IBD is still unclear. However, it is thought that it could be due to a problem with the immune system where, when trying to attack foreign bacteria or viruses, it also attacks the digestive tract’s cells. It has also been associated with gene mutations or a family history. 

Treatment for IBD

IBD can be treated with certain medications such as steroids, which help to control symptoms, but in severe cases, surgery to remove part of the bowel may also be necessary.

What is atrial fibrillation?

Atrial Fibrillation, or AF, is the most common cardiac arrhythmia¹ and is a problem with your heart where it may beat too quickly, too slowly, or irregularly. Your heart has its own electrical system with electrical signals which trigger your heartbeats. AF happens when these electrical signals are not sent out steadily or regularly from the upper chambers (atria) of your heart, causing it to beat randomly. There can be various different types of AF.

Common symptoms of AF

Common symptoms associated with AF include:

• Difficulty exercising 
• Tiredness
• Dizziness 
• Shortness of breath 
• Heart palpitations 

AF causes and risk factors

AF can be caused by heart diseases, high blood pressure, lung diseases, thyroid diseases or infections from viruses. Heart surgery or stress caused by illness or surgery can also be causes of AF.²

There are also certain lifestyle choices which can trigger AF episodes, such as using illegal drugs, smoking, drinking too much alcohol or caffeine and taking medicines that contain stimulants.²

Treatments 

Treatment for AF includes medications, having a pacemaker fitted, or ‘ablation’ and ‘cardioversion’ - procedures to restore a regular heartbeat. 

Are AF and IBD linked? 

At first glance, it is easy to assume that a condition affecting the digestive system and a condition affecting the heart would not be connected. However, recent study results have begun to suggest the opposite. 

Study results

There have been studies over the past few years which have proposed a link between IBD and an increased risk of AF. In fact, a study in Denmark found that IBD was associated with a higher risk of AF - in this study, AF was more common in patients hospitalised with IBD.³

Active IBD vs IBD in remission

However, a key point in these study results was the difference in the risk of AF between someone with active IBD and someone with IBD in remission. IBD is considered active when the person’s symptoms are flaring up due to severe inflammation. We say that IBD is in remission when there is less or even no inflammation, and therefore the person is not experiencing symptoms.

The difference between these is crucial when talking about the associated risk of AF, because the results showed that there was more than a two-fold increased risk of AF during active IBD and flare-ups, but there was no increased risk during times when no symptoms were present.³ So, whilst there is an apparent link between IBD and AF, it only appears to be relevant if you are currently experiencing IBD symptoms. 

Other factors to consider

The increase in the risk of AF for IBD patients was also not found to be equal for all patients. In the study’s IBD hospitalisations, patients with AF were, on average, significantly older - with a mean age of 70.9 years vs 45.0 years for those without AF.³ Meaning that if you are suffering from active IBD, the older you are, the more likely you are to be at a higher risk of AF.

It also seems that if you are an IBD patient with another disease as well (this is called a comorbidity) such as diabetes, you may also be at a higher risk of developing AF given that a higher proportion of IBD patients with AF in the study had other diseases.³

There was, however, no significant change in trend across gender and race, meaning these two factors are not likely to affect the associated AF risk.³

Complications 

Hospitalised IBD patients with AF were also found to experience more complications than those without AF, such as a need for blood transfusions, acute respiratory failure (when your lungs cannot work properly) and pulmonary embolisms (when a blood clot is blocking a blood vessel in the lungs).³

IBD patients with AF also had to stay in hospital longer during the study than those without AF- on average 6.5 vs 4.9 days.³

Why are they related to each other?

It is clear from the research so far that there is probably a link between active IBD and your risk of AF. But why is that so? What is it about active IBD that can increase your risk of AF? How can a problem with your stomach affect your heart? Well, it all may come down to the inflammation caused by IBD. 

Inflammation 

As mentioned before, IBD refers to two conditions (Crohn’s and ulcerative colitis), and these two conditions result in inflammation of the digestive system.² Over the last ten years, evidence has proved that inflammation like this can play a vital role in the way AF develops.³

This is because inflammation is linked to several processes in the body which can ultimately lead to changes to the heart’s atria (upper chambers). In other words, inflammation (like that seen in IBD) can cause changes to the electricity and structure in our heart, and these changes then make AF more likely.⁴

C-reactive protein and interleukin-6

The inflammation in IBD patients can also mean that they have higher levels of C-reactive protein and interleukin-6 in their bodies.⁵ C-reactive protein is released by the liver into the bloodstream to fight inflammation⁶, and interleukin-6 is produced in the places in the body that are inflamed.⁷ Both of these can also lead to changes within the heart, again making AF more likely.⁵

The link: the bottom line

In essence, it has long been established that inflammation can play a crucial role in the development of AF. IBD is, by its very nature, an inflammatory disease. When patients are suffering from active IBD they are experiencing inflammation. The impact of this inflammation on the heart can make AF more likely, and this is where we see the link between the two conditions. 

However, the link is not yet well established given the small amount of research available to this day. Scientific journals and bodies are calling for more studies to help us better understand how this association between the two conditions works. 

Summary 

In summary, initial research is beginning to show that there may be a link between Inflammatory Bowel Disease and Atrial Fibrillation. What’s clear from the studies and information available is that patients hospitalised for active IBD can be more likely to suffer from AF as well. This could be due to the effects of the inflammation from the IBD, which can cause changes to the heart. It could also be due to higher levels of c-reactive protein and interleukin-6. Other factors involved include comorbidities and age, which can have a significant impact on an IBD patient’s risk of AF too. All in all, there is a long way to go in the research field to truly uncover the inner workings of the relationship between these two conditions.