Clinical Subject Page

Infective Endocarditis

Also called

Bacterial Endocarditis (IE)

ICD-10

I33.0

Specialty

Cardiology

Onset

Acute or Subacute

Reviewed

June 2026

On This Page

Overview

Overview
Etiology & Risk Factors

Etiology & Risk Factors
Pathophysiology

Pathophysiology
Clinical Presentation

Clinical Presentation
History Taking

History Taking
Investigations

Investigations
Diagnosis

Diagnosis
Management

Management
Complications

Complications
Prognosis

Prognosis
Key Points / Clinical Pearls

Key Points / Clinical Pearls

Overview

Infective endocarditis (IE) is an infection of the endocardium that most commonly involves one or more heart valves. It usually develops following bacteremia. IE may be acute (hours to days) or subacute (weeks to months). Without treatment, it is typically fatal.

Teaching point Three sets of blood cultures should be obtained before initiating antibiotic therapy whenever possible.

Etiology & Risk Factors

-Common causes

Staphylococcus aureus (most common cause of acute IE)
Viridans streptococci (common cause of subacute IE)
Enterococci
HACEK organisms

-Risk factors

Dental procedures
Surgery
Distant primary infections
Nonsterile injections/intravenous drug use
Prosthetic heart valves
Congenital heart disease
Previous valve damage
Invasive procedures

Pathophysiology

-Disease mechanism

Valvular endothelial injury occurs.
Platelets and fibrin form a sterile vegetation.
Bacteremia allows microorganisms to colonize the vegetation.
Vegetations enlarge and destroy the valve, causing regurgitation.
Vegetations may embolize to distant organs.

-Valve involvement

Mitral valve (most common)
Aortic valve
Tricuspid valve
Pulmonary valve

In people who inject drugs, the tricuspid valve is most commonly affected.

Clinical Presentation

Constitutional symptoms

Fever
Chills
Fatigue
Malaise

Cardiac findings

New or changing heart murmur
Signs of heart failure

Organ involvement

Glomerulonephritis
Septic embolic stroke
Other embolic manifestations

Important Note Suspect infective endocarditis in any patient with fever and a new or changing heart murmur, especially if risk factors are present. Classic peripheral signs are absent in most patients.

History Taking

Important questions include:

Recent dental procedures
Recent surgery
History of intravenous drug use
Previous infective endocarditis
Prosthetic heart valve
Congenital heart disease
Recent bloodstream infection
Duration of fever and constitutional symptoms

Investigations

Diagnosis is based on:

Blood cultures
Echocardiography
Histopathology (when available)
Imaging studies
Assessment using the 2023 Duke-ISCVID criteria

Diagnosis

Home Home Clinical Cases Cardiovascular System Clinical Cases Infective Endocarditis

Management

1. Antimicrobial therapy

Start high-dose intravenous bactericidal antibiotics after obtaining appropriate blood cultures.
Treatment should be guided by the causative organism and antimicrobial susceptibility.
Therapy is generally prolonged, usually 4–6 weeks.
Native-valve streptococcal endocarditis: typically 4 weeks, with gentamicin sometimes used during the initial period in selected cases.
Prosthetic-valve endocarditis: generally requires at least 6 weeks of antimicrobial treatment.
Treatment should be modified once the organism and sensitivities are available.
Monitor:
- Clinical response
- Blood cultures
- Renal function
- Drug toxicity where relevant

2. Cardiac surgery

Surgery is required in a substantial proportion of patients, particularly when complications cannot be controlled with antibiotics alone.

Major indications:

Heart failure due to valve destruction
Persistent/uncontrolled infection despite antibiotics
Large left-sided vegetations with systemic embolisation or high embolic risk
Perivalvular/intracardiac abscess
Prosthetic-valve endocarditis, particularly complicated infection
Fungal endocarditis
Significant valve obstruction or severe valve dysfunction

Surgery involves debridement of infected tissue with valve repair or replacement when necessary. Antimicrobial therapy should be started before surgery.

3. Management of complications

- Heart failure: treat heart failure while addressing the underlying valve destruction; severe valve damage may require urgent surgery.
- Embolic complications: assess for cerebral, splenic, renal and other systemic embolisation.
- Perivalvular abscess/conduction abnormalities: require urgent assessment for surgical treatment.
- Persistent fever/bacteraemia: reassess antimicrobial sensitivity, search for uncontrolled infection or another source, and consider surgery.

Complications

Cardiac

Valvular regurgitation
Heart failure
Prosthetic valve dehiscence
Perivalvular abscess
Myocarditis
Conduction abnormalities (e.g., AV block)

Embolic

Stroke
Renal infarction
Splenic infarction
Pulmonary embolism (right-sided IE)
Septic emboli
Mycotic aneurysm

Other

Lung abscess
Brain abscess
Meningitis
Acute kidney injury
Splenic abscess

Prognosis

IE is a serious disease.
Without treatment, it is typically fatal.
Early diagnosis, prolonged IV antibiotics, and surgery when indicated improve outcomes.

Key Points / Clinical Pearls

IE is an infection of the endocardium, usually involving heart valves.
S. aureus commonly causes acute IE.
Viridans streptococci commonly cause subacute IE.
Obtain blood cultures before starting antibiotics whenever possible.
Echocardiography is central to diagnosis.
Treatment requires prolonged IV antibiotics.
Selected high-risk patients require antibiotic prophylaxis before certain dental and other high-risk procedures.
Heart failure is the most common cause of death in IE.

Yallowitz AW, Decker LC. National Center for Biotechnology Information (NIH). Infectious Endocarditis, StatPearls.
Delgado V, Marsan NA, De Waha S, et al. 2023 ESC Guidelines for the Management of Endocarditis. Eur Heart J. 2023;44:3948-4042. PMID: 37622656.
Fowler VG, Durack DT, Selton-Suty C, et al. The 2023 Duke-ISCVID Criteria for Infective Endocarditis: Updating the Modified Duke Criteria. Clin Infect Dis. 2023;77:518-526. doi: 10.1093/cid/ciad271.
MedlinePlus, National Library of Medicine (NIH). Infective Endocarditis: Medical Encyclopedia.
National Center for Biotechnology Information (NIH). Prosthetic Valve Endocarditis, StatPearls.

Category	Criteria	Key Findings
Pathological Criteria	Definitive pathological evidence	Identification of pathogens or characteristic histological features of active infective endocarditis in tissue or implanted cardiac material.
Major Clinical Criteria	Microbiological evidence	Typical IE pathogens from ≥2 blood culture sets, or specific microbiological evidence (e.g., Coxiella burnetii, Bartonella spp., Tropheryma whipplei).
	Imaging evidence	Echocardiography or cardiac CT showing characteristic IE findings (e.g., vegetations, abscess, new valvular regurgitation); FDG-PET/CT suggestive of IE in selected patients; direct surgical evidence.
Minor Clinical Criteria	Predisposing conditions	Predisposing heart disease, previous IE, cardiac implantable electronic device (CIED), or injection drug use.
	Fever	Temperature >38°C (100.4°F).
	Vascular phenomena	Evidence of embolic or vascular complications.
	Immunologic phenomena	Immunologic manifestations consistent with IE.
	Microbiological evidence	Positive blood cultures or molecular tests that do not fulfill major criteria but are consistent with IE.
	Additional imaging/clinical findings	Abnormal FDG-PET/CT after recent prosthetic implantation or new valvular regurgitation on auscultation when echocardiography is unavailable.