Infective Endocarditis

How endocarditis develops

Normally, blood flows smoothly over healthy heart valves. When a valve is damaged, abnormal, or artificial, turbulent flow creates small areas where platelets and fibrin collect. If bacteria enter the bloodstream, from the mouth, skin, an IV line, injected drugs or the urinary or gut tract, they can stick to these areas and multiply. The result is a vegetation, a mass of bacteria, platelets and fibrin, which:

• destroys valve tissue, causing leaks and heart failure
• can form abscesses in the heart
• can break off (embolize) to the brain, lungs, kidneys, spleen or limbs
• seeds bacteria into the blood continuously

Aggressive bacteria such as Staphylococcus aureus can infect even normal valves.

Risk factors

Highest-risk heart conditions

• artificial (prosthetic) heart valves, including transcatheter valves, and valve repair material
• previous infective endocarditis
• certain congenital heart diseases, especially unrepaired cyanotic disease or recent repair with prosthetic material
• heart transplant with valve disease

Other risk factors

• injection drug use, which commonly affects the tricuspid valve on the right side of the heart
• implanted pacemakers and defibrillators
• long-term IV catheters and hemodialysis
• rheumatic heart disease and degenerative valve disease (see mitral valve disease and aortic valve disease)
• older age, diabetes and a weakened immune system
• poor dental health

Symptoms

Endocarditis can be acute, developing over days with high fever and rapid deterioration (typical of staph), or subacute, developing over weeks with vague symptoms (typical of strep):

• fever and chills (present in most cases)
• night sweats, fatigue, loss of appetite and weight loss
• muscle and joint aches
• shortness of breath and leg swelling from valve damage
• a new or changed heart murmur
• small red or purple spots on the skin, inside the mouth or eyelids (petechiae)
• splinter-like bleeding lines under the nails
• painful red bumps on the fingertips (Osler nodes) or painless flat spots on the palms and soles (Janeway lesions)
• blood in the urine
• signs of embolism: stroke, sudden limb pain, flank or left upper belly pain

Diagnosis

• Blood cultures: at least 3 sets from separate draws, ideally before antibiotics, to identify the bacteria.
• Echocardiogram: a transthoracic scan first; a transesophageal echocardiogram (TEE), with the probe passed down the esophagus, gives detailed views and is usually needed with prosthetic valves or when suspicion remains.
• Other imaging: CT, PET-CT (especially for prosthetic valves and devices), and brain MRI.
• Blood tests: blood count, inflammatory markers, kidney function; urine tests.
• ECG: may show conduction problems from an abscess.

Doctors use the updated Duke criteria, combining blood culture and imaging findings with clinical features, to make the diagnosis.

Treatment

Antibiotics

High-dose IV antibiotics chosen for the specific organism, usually for 4 to 6 weeks. Some stable patients can complete treatment with outpatient IV therapy or, in selected cases, switch to oral antibiotics after an initial IV phase, based on recent trial evidence.

Surgery

Surgery to repair or replace the valve is needed in about half of patients, especially with:

• heart failure from valve damage
• uncontrolled infection, abscess or resistant organisms
• large vegetations with high risk of embolism
• infected prosthetic valves or devices (devices are usually removed)

Supportive care

Care is best delivered by a multidisciplinary "endocarditis team" including cardiologists, cardiac surgeons and infectious disease specialists. For people who inject drugs, treatment of substance use disorder is part of care and reduces reinfection.

Complications

• heart failure and valve destruction
• stroke and other embolic events
• heart abscess and heart block
• kidney damage
• mycotic aneurysms (infected bulges in arteries)
• sepsis

Outlook

Infective endocarditis remains serious, with in-hospital mortality of roughly 15 to 30 percent depending on the organism and complications. Prompt diagnosis, appropriate antibiotics and timely surgery improve survival. Survivors are at higher risk of recurrence and need ongoing follow-up.

Prevention

• good dental hygiene and regular dental checkups are the most important prevention for most people
• antibiotics before dental procedures are recommended only for the highest-risk groups (prosthetic valves, previous endocarditis, certain congenital heart disease, heart transplant with valve disease), for procedures that involve the gums or the tooth root area
• avoid tattoos and piercings from unlicensed providers
• careful IV line care
• for people who inject drugs: sterile equipment, syringe services and treatment for substance use

Frequently asked questions

What is infective endocarditis?

Infective endocarditis is an infection of the heart's inner lining, usually the valves, caused by bacteria or rarely fungi entering the bloodstream. It forms growths that damage valves and can send clots to the brain and other organs.

What are the early signs of endocarditis?

Early signs include persistent fever, chills, night sweats, tiredness, aches and loss of appetite. Some people notice breathlessness, small spots on the skin or under the nails, or have a new heart murmur. It can progress quickly with staph infections.

Who needs antibiotics before dental work?

Only people at highest risk: those with artificial heart valves or valve repair material, previous endocarditis, certain congenital heart conditions, or heart transplants with valve problems. Most people with heart murmurs or mitral valve prolapse do not need them.

Is endocarditis curable?

Yes, many people are cured with several weeks of IV antibiotics, often combined with valve surgery. It is a serious illness with significant risks, so early diagnosis and specialist care are important.