Overview

Endocarditis, also known as infective endocarditis, is a rare but very serious heart condition, which affects the inner lining of the heart chambers and valves. Because of its seriousness, it requires a quick diagnosis and prompt treatment. The good news is that most people who receive prompt treatment recover fully. However, in some cases, endocarditis can lead to serious complications. One of the major potential complications of endocarditis is a stroke.

What is endocarditis?

Endocarditis is the inflammation of the inner lining of heart valves, and sometimes heart chambers. This lining is called the endocardium. The inflammation is most likely due to an infection by a bacteria, but can also be due to fungi or other germs. Certain medical procedures, such as dental procedures and endoscopic examinations, can introduce germs into your blood. Moreover, in some cases, microbes that are on your skin, in your mouth, intestines, or your respiratory system can get into your bloodstream. These microbes can travel to your heart attach themselves to your heart tissue and cause damage to it. Healthy heart tissue is usually resistant to the infection, however,  germs can more easily attach themselves to diseased or damaged heart tissue.

Staphylococcus aureus is the most common germ to cause endocarditis and is responsible for approximately 31.2% to 44.1% of cases.^1,2

Globally, endocarditis affects around 3-10 per 100000 people per year and has a high mortality rate of around 25%.³ The number of endocarditis cases reported in 2019 was 1,090,530, while the number of deaths was 66,320.³

What are the risk factors?

The risk of endocarditis appears to be twice more likely in males than females. Additionally, the average age of people with endocarditis is over 65 years old.⁴ People who are most at risk of developing endocarditis are the ones who:⁵

• Have valve abnormalities – such as congenital heart disease, rheumatic heart disease, mitral valve prolapse, hypertrophic cardiomyopathy or bicuspid aortic valves
• Have a prosthetic heart valve
• Have implanted cardiac devices – such as pacemaker
• Are intravenous drug users
• Are on immunosuppressive medications – like people with cancer or those who have received a transplant
• Have received a recent antibiotic course
• Had a recent dental procedure or open wounds
• Have catheters, such as for haemodialysis, or intravenous lines placed

Symptoms and signs of endocarditis

The symptoms of endocarditis differ from person to person. These symptoms can develop slowly or rapidly, and depend on the person’s general health and the kind of germ that caused the infection. Potential symptoms include:

• Joints and muscle pain
• Chest pain, especially if you feel this pain when you breathe
• Fatigue
• Fever and chills
• Night sweats
• Shortness of breath
• Swelling in the feet, legs or belly
• A whooshing or swishing sound in your heart (murmur)
• Weight loss
• Blood in the urine
• Tenderness in the spleen area
• Flat spots on your feet or the palms of your hands. They should be painless and can be purple, red or brown (called Janeway lesions)
• Painful red-purple, slightly raised, tender lumps, often with a pale centre on the tips of the fingers and/or toes (called Osler nodes)
• Pinpoint-sized purple, red or brown spots of bleeding under the skin or mucous membranes (called petechiae)

Diagnosing endocarditis

Endocarditis can present with similar symptoms to other diseases, which makes it hard to diagnose. To diagnose endocarditis, the following examination may be used:

• Blood tests – can help with identifying what type of germ is causing endocarditis
• An echocardiogram – is used to look at the heart and surrounding blood vessels, and it is helpful in assessing the damage in your heart
• An electrocardiogram (ECG) – can be used to check your heart rhythm and see if there are any abnormalities
• A chest X-ray – can be used to see if there is fluid build-up in your lungs
• An MRI scan – can be used to visualise your heart, including chambers, valves and muscles

Potential complications of endocarditis

Endocarditis causes abnormal growths called vegetations. Vegetations form a mass in the heart consisting of germs and inflammatory cells meshed together with platelets (cell fragments in your blood that help with clotting) and fibrin (a protein involved in blood clotting).⁶ They can release toxins and enzymes which damage your heart. Vegetations can also break off and travel to different parts of your body, including legs and arms, the brain, lungs, kidneys and other organs. This can lead to different complications, including:

• Heart failure
• Heart valve damage
• Stroke
• Development of abscesses (a build-up of pus) in the heart, brain, lungs and other organs
• Pulmonary embolism, which is caused by a blood clot in your lung
• Kidney damage
• Enlarged spleen

What is a stroke?

Stroke is a serious condition that occurs when the blood supply to the brain is either restricted or stopped. This can lead to permanent damage or even death. The two main types of stroke are:

• Ischemic stroke – Ischemic stroke is caused by blood clots or other particles blocking or reducing blood flow to the brain. As a result, the supply of oxygen and nutrients to the brain is reduced and the brain cells start dying. Ischemic stroke is the most common type of stroke, making up around 85% of all strokes
• Haemorrhagic stroke – this type of stroke is caused by ruptured blood vessels, leading to uncontrollable bleeding inside of your brain or in the space between your brain and its outer covering layer. This blood pools and can put pressure on your brain and damage it

Symptoms of stroke

Stroke can manifest itself in many symptoms, which include:

• Paralysis or weakness of one side of your body
• Blurred, or loss of, vision
• Nausea
• Dizziness
• Confusion
• Struggling with understanding what others are saying
• Struggling with balance and coordination
• Struggling with speech
• Difficulty swallowing (dysphagia)
• Sudden and severe headache
• Loss of consciousness

How can endocarditis lead to stroke?

Stroke is the second most common complication in left-sided endocarditis after congestive heart failure.⁷ Between 20 to 35% of endocarditis patients develop ischaemic stroke. This is due to two major causes:⁷

• Embolism - happens when vegetations break off and travels to the blood vessels in the brain, blocking the blood flow 
• Mycotic aneurysm rupture – mycotic aneurysm is an infection of the arterial blood vessel wall, which causes it to dilate. Mycotic aneurysms in endocarditis are associated with high risks of bleeding in the brain

Stroke can therefore complicate the treatment process of endocarditis. Ischaemic stroke can delay surgical treatment of endocarditis by 2-4 weeks, while haemorrhagic stroke can delay it by at least 4 weeks.⁷

What factors increase the risk of stroke for endocarditis patients?

There are certain factors that may increase the risk of stroke in endocarditis patients, which include:⁸

• Older age
• Male gender 
• Fungal infection
• Development of vegetation in mitral valve
• Atrial fibrillation
• Staphylococcal infection
• Prior stroke
• Larger vegetation

Risk of stroke recurrence

Endocarditis patients who develop a stroke have a higher risk of having another one. In the first year after endocarditis diagnosis, patients who suffered from a stroke are 3.2 times more likely to experience stroke again than patients who did not suffer from one.⁸

How to prevent endocarditis?

There are some things that you can do to help reduce your risk of endocarditis:⁹

• Maintaining good oral hygiene – you should go for a check-up with your dentist regularly, and regularly brush and floss your teeth
• Antibiotic prophylaxis before having invasive dental or oral procedures – if you are at an increased risk of endocarditis (have a prosthetic heart valve or a certain condition), prophylactic use of antibiotics could reduce your risk of infection after a dental/oral procedure
• Prompt treatment of infections - in particular when infections are caused by germs that are likely to cause endocarditis
• Antibiotic prophylaxis before or after invasive surgery – this will reduce the risk of surgical site infection, for example, after implantation of prosthetic heart valves

Summary

Endocarditis is a serious heart condition that has a high mortality rate. It is associated with several severe complications, including stroke, as it increases the risk of brain embolic events. However, there are some things that you can do to reduce your risk of endocarditis, including practising good oral hygiene and treating any infections promptly.