Endocarditis: what are the symptoms
and when to suspect it

Article written and reviewed by Dr Luca Moretti

Infective endocarditis is an infection of the endocardium that mainly affects the heart valves and, in some cases, prosthetic material or intracardiac devices. It may begin suddenly or develop slowly, and precisely for this reason there is no single symptom that allows a person to recognize it on their own.
The most frequent sign is fever, often accompanied by chills, fatigue, night sweats, muscle or joint pain and loss of appetite. Suspicion becomes more significant when these symptoms have no clear explanation and occur in a person with risk factors, for example a prosthetic valve, previous endocarditis or certain heart diseases.

Symptoms and signs that may occur include:

• persistent or recurrent fever or low-grade fever;
• chills and sweating, especially at night;
• marked fatigue, weakness and general malaise;
• shortness of breath or reduced exercise tolerance;
• loss of appetite or unintentional weight loss;
• muscle or joint pain;
• leg swelling or other signs of heart failure;
• more rarely, small skin lesions, petechiae or manifestations caused by emboli.

These symptoms are nonspecific: influenza, other infections and many noncardiac conditions can cause similar symptoms. Endocarditis is therefore not diagnosed on the basis of symptoms, but through medical assessment that, when suspicion is concrete, primarily includes blood cultures and cardiac imaging. The monograph on infective endocarditis discusses the disease in depth, whereas this guide focuses on what the patient may notice and when the clinical picture warrants prompt assessment.

What are the most common symptoms of endocarditis

Fever is the most common manifestation, but it should not necessarily be imagined as a very high temperature. It may be continuous, intermittent or mild and may be associated with chills, night sweats and a general feeling of malaise. In the European EURO-ENDO registry, fever was present in about three quarters of patients at presentation, while the guidelines emphasize that subacute or chronic forms may have low-grade fever or even no fever.
Fatigue, loss of energy, reduced appetite, muscle or joint pain and weight loss are also common. Taken individually, these symptoms do not indicate endocarditis; they become more significant if they persist without an obvious cause or occur in a person who belongs to a risk category.

When the infection interferes with the function of a heart valve, dyspnea may occur, initially during exertion and, in more severe cases, even at rest. Ankle and leg swelling, rapid weight gain due to fluid retention, difficulty breathing when lying flat or waking at night because of shortness of breath may also occur. These are signs that may indicate heart failure and require prompt assessment.
The physician may also detect a new or changed heart murmur, but this is a finding on physical examination and not a symptom that the patient can recognize reliably.

Acute and subacute endocarditis: why the symptoms can be very different

Some forms of endocarditis have an acute course: fever is high, the patient rapidly appears very ill and cardiac, neurological or septic complications may develop within a short time. Staphylococcus aureus is one of the microorganisms that can cause aggressive presentations, even on previously normal valves.
Other forms instead evolve subacutely. The temperature may remain only slightly above normal for weeks, with fatigue, sweating, weight loss, diffuse pain or a gradual decline in the ability to perform usual activities predominating. This slow evolution can lead the symptoms to be attributed to a viral infection, age, stress or other diseases, delaying recognition.

In older and immunocompromised people, the presentation may be even less characteristic. The absence of high fever therefore does not exclude endocarditis when clinical features make it plausible.
The presence of a prosthetic valve, a transcatheter valve or a cardiac device can also alter the clinical picture. In these patients, persistent fever without an evident focus, especially when associated with weakness, dyspnea or abnormalities on blood tests, deserves particular attention.

Which signs may indicate a complication

Endocarditis can damage a valve and cause heart failure, or fragments of an infected vegetation may detach and reach other organs through the bloodstream. For this reason, in some patients the first obvious sign is not fever but a complication.
A cerebral embolism may present with sudden weakness or loss of sensation on one side of the body, difficulty speaking, facial asymmetry, visual disturbances or altered consciousness. These are symptoms compatible with stroke and require an immediate call to 112 or 118, regardless of the cause.

In right-sided endocarditis, which is more common in certain settings such as injection drug use or infections of intravascular devices, infected material can embolize to the lungs. Shortness of breath, chest pain, cough or blood in the sputum may occur. In left-sided forms, emboli can reach not only the brain but also the spleen, kidneys or limbs and cause sudden pain or symptoms specific to the affected organ.
The classic skin manifestations described in textbooks, such as Janeway lesions, Osler nodes, petechiae or splinter hemorrhages beneath the nails, are not present in most patients today. They may provide useful clues to the physician, but their absence is not reassuring and their presence does not allow self-diagnosis.

When to truly suspect endocarditis and when to seek assessment

A common fever in a person without risk factors is much more often due to other causes. Suspicion of endocarditis increases when fever is persistent or has no clear source and is associated with predisposing conditions. These include previous endocarditis, a prosthetic valve, material used for valve repair, certain congenital heart diseases, certain valvular heart diseases, cardiac devices, hemodialysis, vascular catheters or injection drug use.
In a person at high risk, new-onset fever or chills without an obvious explanation should prompt rapid contact with the physician or the referring cardiology center. ESC guidelines recommend that these patients explicitly state that they are at risk of endocarditis because, when there is clinical suspicion, it may be important to obtain blood cultures before starting empirical antibiotics.

It is not useful to take leftover antibiotics from previous treatments or to start them independently "just in case": in addition to possible adverse effects, treatment started before blood sampling can make it more difficult to identify the causative microorganism. If the clinical picture is compatible with a significant infection, decisions about antibiotics must be made by a physician.
Emergency care is instead necessary if severe breathing difficulty, loss of consciousness, signs of stroke, severe chest pain, marked confusion or rapid deterioration in general condition occur. In these situations, a scheduled appointment should not be awaited.

Frequently asked questions about endocarditis symptoms

What is the most common symptom of endocarditis?
Fever is the most frequent sign, but it may be high, low-grade or intermittent. On its own, it cannot distinguish endocarditis from the many other causes of fever.

Can you have endocarditis without fever?
Yes. Some subacute forms and some older or immunocompromised patients may have low-grade fever or no obvious fever. Fatigue, dyspnea, weight loss or embolic complications may predominate.

How quickly do symptoms appear?
There is no single time course. Acute forms may worsen over a few days, whereas subacute forms may evolve for weeks with initially subtle symptoms.

Does fever after dental treatment mean endocarditis?
No. In the vast majority of cases, fever after a dental procedure has other explanations. However, persistent fever without a clear cause in a person at high risk of endocarditis warrants prompt medical assessment, especially after an invasive procedure or in the presence of other symptoms.