Endocarditis: What You Should Know About This Potentially Deadly Heart Condition

Infections are a part of life, but they aren’t all created equal. Some are more severe than others. Endocarditis — an infection of the inside of the heart — is one of them. 

Endocarditis is rare, but it’s important to know the risk factors. We’ll also review the cause, symptoms, diagnosis, and treatment of this life-threatening condition.

What is endocarditis?

Endocarditis is an infection of the inside of the heart. A couple different parts of the heart can become infected. These include:

• Heart valves, like the aortic valve and mitral valve

• Inner lining of the heart (endocardium)

• Devices placed inside the heart, like pacemakers

Endocarditis is rare, affecting only about 5 in every 100,000 people per year. It’s more common in people older than 65, and it’s more common in men than women.

Is endocarditis a serious condition?

Yes. Endocarditis can be life-threatening. Some types of endocarditis are more aggressive than others (see below), but all require urgent care in a hospital. Endocarditis can cause severe complications both inside and outside of the heart.

What causes endocarditis?

Fortunately, endocarditis isn’t very common. That’s because two things are necessary for endocarditis to occur: 

• Abnormalities inside of the heart

• Germs in the bloodstream (most commonly bacteria, though other types of germs, like fungi, can cause endocarditis)

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When bacteria enter the bloodstream, they can travel just about anywhere in the body. If the inside of the heart is abnormal, bacteria can stick to the abnormal areas and cause infection. 

What are the risk factors for endocarditis?

Risk factors for endocarditis make it more likely to happen, but they’re not causes. They include things that make the structure of the heart abnormal or increase the risk of germs in the bloodstream. 

Conditions that make the structure of the heart abnormal include: 

• Congenital heart disease (birth defects of the heart)

• Artificial heart valves 

• Conditions that affect the heart valves (like aortic stenosis)

• Devices placed inside the heart (like pacemakers)

• Rheumatic heart disease, when strep throat infection (rheumatic fever) damages the heart valves (this is rare in the U.S., since treatment with antibiotics can prevent it)

• A prior history of endocarditis, which can damage the inside of the heart

• IV (intravenous) drug use, since tiny particles that can damage heart valves may enter the bloodstream when injecting drugs

Conditions that increase the risk of germs in the bloodstream include: 

• Conditions that weaken the immune system: Examples are poorly controlled Type 2 diabetes and liver failure (cirrhosis).

• Medications that weaken the immune system:Chemotherapy is an example.

• IV drug use: Anything inserted into the veins can let bacteria into the bloodstream.

• Chronic kidney disease that requires hemodialysis: This both weakens the immune system and requires insertion of a needle into the veins.

• Permanent catheters or ports (“lines”): These may be needed for chemotherapy. 

• Dental procedures: These procedures can let bacteria from the mouth into the bloodstream. If you have an underlying heart abnormality, your provider might recommend preventive antibiotics before a dental procedure.

• Severe infections: Bacteria can spread from the initial area of infection (like the skin) into the bloodstream.

What are the symptoms of endocarditis?

Symptoms of endocarditis are different for every person who has it. Some people may become very sick, very quickly (acute endocarditis). But others may feel unwell for weeks to months (subacute endocarditis) before getting a diagnosis. This is because some germs infect and damage the heart quickly, whereas others take longer to do so.

The most common signs and symptoms of endocarditis include:

• Fever and chills

• Night sweats

• Weight loss 

• Lack of appetite

• Fatigue

• Body aches, joint aches, and headache

• New heart murmur heard on physical exam (a whooshing sound caused by abnormal blood flow through a heart valve)

About 25% of people with endocarditis will also have symptoms in other parts of the body at the time of diagnosis. This is because the heart is a moving, beating organ. When the heart beats, little balls of cells and bacteria (septic emboli) can be flicked off and infect other parts of the body. 

For example, septic emboli can cause different issues to these areas:

• Joints: pain, swelling, or joint infection 

• Skin and nails:rashes, or tiny red lines in the fingernails 

• Lungs: cough or shortness of breath 

• Brain:stroke 

• Kidneys: abnormal urine tests and worsening kidney function

• Eyes: vision changes

How do you diagnose endocarditis?

Healthcare providers diagnose endocarditis using clues from symptoms, a physical exam, and various tests. The diagnosis can be tricky to make since symptoms differ from person to person.  Some tests might be positive in some people but not in others. 

Tests might include:

• Blood cultures: This blood test looks for germs in the blood. Some germs grow quickly. Others grow slowly.

• Echocardiogram: This is an ultrasound of the heart that can look for clumps of bacteria and cells (vegetations) on the heart valves.

• Transesophageal echocardiogram (TEE): If a regular echocardiogram is negative, a healthcare provider might perform a TEE to take a better look at the heart. This is a minor procedure that involves inserting an ultrasound device into the mouth and down the esophagus to look at the heart from the backside.

Other tests might be necessary to rule out other conditions that could be causing the symptoms.

Treatments for endocarditis

Treatment of endocarditis requires hospital care. IV antibiotics (infused into the vein) are required for several weeks. In about 50% of cases, surgery may be necessary as well. This can include valve repair or replacement or removal of a device. 

What is the survival rate of endocarditis?

It depends. Many different factors affect the severity of endocarditis. Factors that affect the chances of survival include:

• Age

• Other health conditions

• What type of germ has caused the endocarditis

• How quickly treatment is started, and how well a person responds to treatment

• How many organs outside of the heart are involved

• How much damage has been done to the heart 

Up to 30% of people with endocarditis may die within the first 30 days of infection. This is a scary statistic. But many people do survive endocarditis. 

Is endocarditis contagious?

No. Endocarditis is not contagious.

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Written by:

Samantha C. Shapiro, MD

Samantha Shapiro, MD, is a board-certified rheumatologist and internist with expertise in autoimmune and inflammatory conditions. She founded the division of rheumatology at Dell Medical School at The University of Texas at Austin.

Edited by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined her interests in clinical medicine with her passion for education and content development for many years. She served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

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