What You Should Know About Endocarditis

Endocarditis is an often serious infection (or inflammation) of the heart. Technically, endocarditis is the infection or inflammation of the endocardium, which is the inner heart surface. This means endocarditis is an infection of the heart valves. It can also affect devices (pacemakers, defibrillators, and their wires) as well as artificial valves.

What Happens

In endocarditis, vegetations—or clusters of microbes and human fibrin and platelets—amass on heart valves. They fling back and forth as the valve opens and closes. These vegetations can affect blood flow. They can break away and hurtle towards other parts of the body. This can mean harming the brain and lungs. These vegetations are made up of a motley collection of platelets, fibrin, and the bacteria (or fungi) causing the infection. They can grow larger and larger until proper treatment is started.

Labeled illustration of a human heart

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How Common Is It?

It's not that common. In the US, it affects 1 in 10,000 to 1 in 20,000 Americans a year. However, among those who use intravenous drugs (like heroin), 1-2 in 1000 will be infected (and maybe more).

Who Gets It

Most who get it already had a problem with their heart. Pre-existing heart abnormalities are found in 3 in 4 who develop endocarditis. Usually, this means something was wrong with their heart valves or had a hole in their heart. Some may have had a heart transplant or been born with an abnormal heart. These valve problems are often picked up when a healthcare provider hears a murmur. It can also be picked up through specific testing, such as an ultrasound of the heart called an Echo (Echocardiogram). You should ask your healthcare provider about this if you have any questions.

There are different valves and different types of problems. Some valves are too tight—stenosis. Some valves are too floppy—regurgitation. Of those who develop endocarditis, over 40% will have had a mitral valve problem (specifically mitral regurgitation), while over 25% will have had an aortic valve problem (aortic regurgitation) which are both common valve problems.

Others will get endocarditis because they are more likely to have bacteria flow through their blood. Having bacteria in the bloodstreams risks having bacteria land on the valves. Bacteria can be found in the bloodstream in small amounts for small bits of time, but sometimes these bacterial flows can be more prolonged. This can happen when people have medical or dental procedures. Anytime a needle or scalpel pierces through the skin, there's a risk of bacteria from the skin (or the needle or scalpel) will enter inside. Those who have hemodialysis are particularly at risk (a little less than 8% of endocarditis patients are on dialysis).

Others who are at risk are those who use needles for injection drug use. Almost 10% of endocarditis cases are in those who use intravenous drugs, like heroin.

What It Feels Like

There are different types of endocarditis. These types depend on what bug is infecting you and also whether it's a natural (native) valve or an artificial one that's infected.

The most notable distinction is between acute and subacute infection. Some bacteria normally cause illness quickly. Other bacteria normally cause illness slowly and indolently, where serious damage can occur before anyone knows there's a problem.

Acute Infective Endocarditis can be marked by a high fever, shake chills, extreme fatigue as well as chest pain, shortness of breath which can come suddenly.

Subacute Infective Endocarditis takes longer to be recognized, usually at least 1-2 weeks, but sometimes longer time. Subacute infections are marked by lower fevers, general tiredness, poor appetite, weight loss, back pain, night sweats, mild chills, headache, and pain in muscles or joints. Sometimes noted also are small, tender nodules in finger or toes as well as broken blood vessels in fingernails or toenails (or eyes).

Acute Infective Endocarditis may be caused by Staph Aureus. Subacute is often caused by Streptococcal (Strep) bacteria, especially viridian streptococci, as well as sometimes by enterococci and even types of Staph.

Subacute infections often come from parts of the body where they are normally found in healthy people. Strep infections often form from the mouth through cavities or dental work. Some infections can come from the intestine and enterococci are often found in the genitourinary tract. These bacteria can end up in the bloodstream from medical or surgical procedures.


Beyond acute and subacute, there are many different varieties of infection depending on a) which valve is affected b) which bacteria or fungus is involved c) how chronic the infection is. The valves affected are the Aortic and Mitral more commonly (on the left side of the heart) and the Tricuspid and Pulmonic (on the right side of the heart).

Those who are infected from injection drug use often have right-sided infections (especially the Tricuspid) while this is rarer in others.

Side Effects

One of the big dangers is that the vegetations can flick bits of material to other parts of the body. These are called emboli. These bits can clog up vessels anywhere blood flows—which is anywhere, depending on which side of the heart the valve is on. (The left side usually pumps to the body and brain, while the right side pumps to the lungs). This can cause serious damage and infections in the lungs and brain, causing strokes, as well as many other parts of the body, including the kidneys, liver, spleen, and important blood vessels.

The infections can be hard to clear and continually seed the bacteria in the blood, leading to a serious, uncontrolled infection.

The infections can permanently damage valves and can lead to heart failure.


Most will need a few weeks of antibiotics. Different regimens depending on the infection (and the valve) range from 2 to 6 weeks. This assumes the bacteria clear with the antibiotics.

Some need surgery. This oftentimes includes those who have artificial valves, persistent infections, bad heart failure, heart abscesses as the infection travels into the heart from the valve.

Prevention With an Existing Heart Problem

Some at high risk will receive antibiotics before certain medical or surgical procedures. It is important that you talk to your healthcare provider or nurse, and your dentist about your risk and your concerns before a procedure. Those who are considered at highest risk are, those with a prosthetic (artificial) valve, past Infective Endocarditis, certain congenital heart diseases (heart disease you're born with) and those with heart transplants who have valve problems.

If you have any concerns about being at risk, please speak with a health professional.

Doesn't Rheumatic Fever Cause Heart Problems?

Yes, indeed. Rheumatic fever can cause inflammation throughout the heart, but as the disease persists there is fibrosis of the valve, which can cause it to become too tight or floppy (stenosis or regurgitation). It is caused by Group A strep infections.​

When It's Non-Infectious

It can also be non-infectious. Sometimes this can be associated with rheumatologic and autoimmune disorders.

Is It Just Valves That Become Infected?

The infection can also involve other parts of the inside of the heart including at a "hole in the heart" (such as a defect in the walls separating heart different chambers) and the cords (chordae tendineae) attached to the valves.

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