Infections and Heart disease: Understanding the link

Bacterial and viral infections can give you more than an upset stomach or a runny nose: some infections can affect your heart

More than 50 years ago, animal experiments showed that infections with an avian herpesvirus resulted in arterial disease similar to human atherosclerosis. Since then, multiple studies have established links between bacterial or viral infections and certain heart conditions, like coronary heart disease (CHD). Below, we review some of the best-studied examples of infections influencing heart disease.

What is an infection?

Infection normally occurs when a foreign microorganism, such as bacteria, viruses or parasites, not normally found in your body, manages to enter your body and reproduce. They can also occur when a microorganism that normally inhabits your body overgrowths, causing disease.

Infections can have no symptoms, as pathogens can sometimes go undetected by the immune system. But, often, the immune system manages to detect the invading pathogen and creates an immune response.

Worldwide, infectious diseases kill about 50,000 men, women and children, accounting for about 17 million deaths each year, according to the World Health Organization. In Australia, about 400,000 people acquire infectious diseases every year and 6,300 die from their condition.

While most infectious diseases are manageable and highly preventable, some pathogens can be difficult to detect or treat. A case example has been the COVID-19 pandemic that has affected Australia and the rest of the world.

Infectious diseases and heart disease

Multiple studies have established links between infectious agents and some heart conditions, like coronary heart disease (CHD). In Australia, some important infectious diseases linked to heart disease include:

Helicobacter pylori

This is a bacterium that can infect the lining of the stomach and cause disease. pylori can cause gastritis, which is an inflammation of the stomach lining, as well as ulcers and even stomach cancer. Infections with this bacterium is very common in Australia and worldwide, especially in some age groups. For example, 4 in 10 Australians over the age of 60 are infected with this bacterium. Worldwide, it is estimated that around 4.4 billion individuals are affected by this pathogen. However, only a portion of those infected ever develop symptoms.

Link with Heart Disease

Infections with pylori have been linked with conditions like atherosclerosis, coronary heart disease and stroke.

• Atherosclerosis
  This occurs when fat, cholesterol and calcium accumulate within the wall of arteries and veins, forming plaques that prevent the normal flow of blood. Pieces of this plaque can also dislodge from the artery or vein wall and form a blood clot that effectively blocks blood flow, increasing the chances of a heart attack, stroke, or heart failure. Infection link: Multiple studies in the past decades have reported a role for pylori in the development of atherosclerosis¹. Some of the mechanisms proposed to explain this link so far include:

• Induction of inflammatory responses
  This is our body’s response to invading pathogens^2-4. Studies have shown that immune cells released during inflammatory responses have a role in the development of atherosclerotic plaques^5-6.

• Damage to the endothelium, the cellular lining of blood vessels.
  This has been shown to be a first step in the pathway toward the development of atherosclerotic plaques^7-8

• Dysregulation of lipid metabolism
  This can result in an increase of cholesterol and triglyceride levels in the blood, including high levels of total cholesterol, LDL cholesterol, lipoprotein (a), serum lipids, oxidized low-density protein (oxLDL), and triglyceride concentrations^1,9-11

• Hyperhomocysteinaemia
  This condition refers to high levels of the amino acid homocysteine. High levels of the amino acid are a risk factor for heart disease^12-13

• Coronary Heart disease (CHD)
  CHD is a form of heart disease that occurs when the arteries that deliver oxygenated blood to the heart are blocked by fat deposits, called plaque. As a result, the heart does not receive enough oxygen to function properly. A recent study estimated that infection by pylori increased the risk of CHD by 11%¹⁴. Other studies have shown that infection with this bacterium causes an inflammatory response in the body and that one of the immune cells produced by the body, anti-H. pylori immunoglobulin G (IgG), is associated with an increased risk of CHD. A strain of H. pylori, called Cag-A-positive H. pylori, which has been associated with a higher risk of gastric cancer, has also been linked to CHD¹⁴. However, other studies have questioned the link between H. pylori and CHD, suggesting that co-founding factors might be at play at later stages in life. Nevertheless, the link between H. pylori and CHD early in life has been supported in a recent research review¹⁵.

Group A Streptococcus

This is the causative agent acute rheumatic fever, a condition that can affect the heart, joints, brain, and skin. It is the leading cause of rheumatic heart disease (RHD). Acute rheumatic fever (RH) occurs when someone develops a severe autoimmune response, consequence of infection by group A Streptococcus bacteria. If such an infection is not promptly treated, it can develop as a throat or skin infection (like strep throat or scarlet fever). In some people, infection by this bacteria results in an extreme immune response, called acute rheumatic fever, where the immune system attacks not only the bacteria but also normal body cells, a condition known as an autoimmune response.

Symptoms

Typical symptoms of RH are the result of inflammation affecting the heart, joints, skin or central nervous system, and can include:

• Fever
• Painful or swollen joints
• Small, painless bumps beneath the skin
• Chest pain
• Heart murmur
• Fatigue
• Flat or slightly raised, painless rash
• Jerky, uncontrollable body movements (Sydenham chorea) of hands, feet and face
• Outbursts of unusual behaviour, such as crying or inappropriate laughing

Rheumatic Heart Disease

Acute rheumatic fever can cause long-lasting damage to the heart, a condition called Rheumatic Heart Disease, which occurs when one or more of the heart valves are damaged, causing heart failure. Heart tissue can be affected too, as the extreme autoimmune response can attack any part of the body. While having an acute rheumatic fever does not mean you will develop heart disease, statistics show that about 50% of those who suffer from acute rheumatic fever go on to develop rheumatic heart disease within 10 years.

Studies have also linked heart disease with other types of infection, such as bacterial and viral infections. This includes infections with viruses like cytomegalovirus (CMV), herpes simplex virus-1 (HSV-1), and hepatitis A virus (HAV) as well as with bacteria such as Chlamydia pneumoniae (Table 1)^{1, 16}.

Table 1. Microbial agents associated with atherosclerosis

More recently, studies have linked heart disease with the virus causing the COVID-19 pandemic: SARS-CoV2.

Focus on SARS-CoV-2 infection and heart disease

In December 2019, a novel coronavirus was reported to infect humans in Wuhan, Hubei province, China, causing fever, cough, sore throat, and headaches, and in some people causing more serious conditions, even death. Shortly after it was first reported, the virus spread throughout China and by early 2020 it has become a worldwide pandemic, called COVID-19. Currently, there are more than 21 million people infected and more than 771 thousand have died from COVID-19.

Infections by the SARS-CoV-2 virus commonly cause respiratory symptoms and fever, a small set of those affected also suffer cardiovascular damage. People with underlying cardiovascular disease are also at a higher risk of death from this infectious disease¹⁷.

COVID-19 and heart disease

ACE2 is a protein found in the surface of cells from the lung, heart, blood vessels, kidneys, liver, and gastrointestinal tract. They are also found in epithelial cells, which make up the cell lining of blood vessels and various organs in the body. The main function of ACE2 is to regulate processes like blood pressure, wound healing, and inflammation, through the modulation of the function of a protein called angiotensin II (ANG II), increases blood pressure and inflammation.

The COVID-19 virus, SARS-CoV-2, is able to bind to the ACE2 protein, inhibiting its function as a regulator of ANG II¹⁸. As a consequence, people infected by SARS-CoV-2 experience damage in the lung and heart tissues, where the ACE2 proteins are highly abundant. This becomes more problematic for people who have pre-existing heart conditions. Myocardial injury has been associated with SARS-CoV-2 since the start of the pandemic¹⁹. People with this virus also seem to be more likely to develop blood clots in veins and arteries, which can lead to heart attacks or stroke.

Infections and Modern Functional Medicine in Heart Disease

At the Australian Centre for Functional Medicine, we employ a comprehensive approach to treat and prevent infectious diseases. Our core approach is to strengthen the function of our body’s immune system, which is your most powerful asset to fight infectious diseases. Managing your lifestyle, including diet, exercise and stress levels is a proven way to improve the function of your immune system and overall mental and body health.

We initially perform multiple tests to evaluate the overall health of your body. The results of these tests will inform us about micronutrient deficiencies, and other factors that can affect the function of your immune system and your overall health. We also evaluate other aspects of your health, such as the status of your gut microbiota, which can influence intestinal permeability and affect the ability of your body to fence off pathogens. Finally, we inquire about your lifestyle and address your exercise and stress levels, two important factors that can affect your health and your ability to respond to infectious diseases.

Based on the results of our comprehensive testing and our investigations about your lifestyle, we are able to tailor a treatment that will address your specific needs.

BECOME A PATIENT TODAY and learn how to improve every aspect of your health

BECOME A PATIENT

References

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