Infective Endocarditis (IE)

Background Knowledge 🧠

Definition

• Infection of the endocardial surface of the heart, which may involve heart valves, mural endocardium, or septal defect.

Epidemiology

• Infective endocarditis is a rare disease however, recent trends indicate a growing global incidence.

Pathophysiology

• Bacteria enter the bloodstream and adhere to damaged endocardium or prosthetic valves.

• Formation of infective vegetations; platelets and fibrin entrap the organisms.

• Damage to heart valves leading to regurgitation and heart failure.

Aetiology/Risk Factors

• Commonly caused by bacteria, especially Streptococci, Staphylococci, and Enterococci.
• Other organisms: Fungi (e.g., Candida), HACEK group.
• Risk factors:
  • Prosthetic heart valves
  • Structural heart disease
  • Congenital heart disease (e.g. ventricular septal defect)
  • Intravenous drug use
  • Dental procedures
  • Indwelling catheters
  • Previous infective endocarditis
  • Age

Clinical Features 🌡️

Symptoms

• Constitutional symptoms: Fever, malaise, night sweats, weight loss.

Signs

• Cardiac: Murmurs (new or changed), signs of heart failure.
• Embolisation signs: Stroke, renal infarcts, splenic infarcts.
• Classic findings: Osler’s nodes (painful nodules on fingers/toes), Janeway lesions (painless macules on palms/soles), Roth’s spots (retinal haemorrhages), splinter haemorrhages (under the nails),splenomegaly.

Investigations 🧪

Investigations

• Blood cultures: Multiple sets (3 sets, at least 30 mins apart) to identify the causative organism.
• Blood tests: FBC, CRP, ESR (elevated in inflammation/infection).
• Echocardiography: Transoesophageal (TOE) preferred over transthoracic (TTE) for better visualisation of vegetations and valvular damage.
• Application of the Modified Duke criteria are recommended for the diagnosis of infective endocarditis.

Management 🥼

Management

• Antibiotic therapy: Empirical treatment (based on likely organisms) followed by targeted therapy after culture results.
• Duration: Typically 4-6 weeks, may vary based on organism and location.
• Surgery: Indicated in heart failure, uncontrolled infection, recurrent emboli, and prosthetic valve endocarditis.
• Prophylaxis: Antibiotic prophylaxis before dental or surgical procedures in high-risk patients.

Prognosis

• IE is associated with a relatively high morbidity and mortality.

Complications

• Heart failure
• Systemic embolisation (e.g stroke, pulmonary embolism)
• Abscess formation
• Valvular damage

Key Points

• Infective endocarditis is an infection of the endocardial surface of the heart,
• Risk factors include: prosthetic heart valves, structural heart disease and intravenous drug use.
• Intravenous drug use is most commonly associated with Staphylococcus aureus.
• Common signs include: new or changing heart murmur, Osler’s nodes, Janeway lesions and features of heart failure.
• First line investigations include: blood cultures (multiple sets) and transoesophageal echocardiography (TOE).
• Treatment: 4-6 weeks of antibiotic therapy and surgery if indicated.

 

References

Delgado, V., Ajmone Marsan, N., de Waha, S., Bonaros, N., Brida, M., Burri, H., Caselli, S., Doenst, T., Ederhy, S., Erba, P. A., Foldager, D., Fosbøl, E. L., Kovac, J., Mestres, C. A., Miller, O. I., Miro, J. M., Pazdernik, M., Pizzi, M. N., Quintana, E., Rasmussen, T. B., Ristić, A. D., Rodés-Cabau, J., Sionis, A., Zühlke, L. J. and Borger, M. A. (2023) ‘2023 ESC 

Habib, G., Lancellotti, P., Antunes, M. J., Bongiorni, M. G., Casalta, J.-P., Del Zotti, F., Dulgheru, R., El Khoury, G., Erba, P. A., Iung, B., Miro, J. M., Mulder, B. J., Plonska-Gosciniak, E., Price, S., Roos-Hesselink, J., Snygg-Martin, U., Thuny, F., Tornos Mas, P., Vilacosta, I. and Zamorano, J. L. (2015) ‘2015 ESC Guidelines for the management of infective endocarditis: The Task Force for the Management of Infective Endocarditis of the European Society of Cardiology (ESC). Endorsed by: European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Nuclear Medicine (EANM)’, Eur Heart J, 36(44), pp. 3075-3128.

Thornhill, M. H., Dayer, M. J., Nicholl, J., Prendergast, B. D., Lockhart, P. B. and Baddour, L. M. (2020) ‘An alarming rise in incidence of infective endocarditis in England since 2009: why?’, Lancet, 395(10233), pp. 1325-1327.

Isidre Vilacosta, Carmen Olmos Blanco, Cristina Sarriá Cepeda, Javier López Díaz, Carlos Ferrera Durán, David Vivas Balcones, Luis Maroto Castellanos and San, A. (2016). Prognosis in Infective Endocarditis. Springer eBooks, pp.89–103. doi:https://doi.org/10.1007/978-3-319-32432-6_8.

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