Infective Endocarditis

• Infective endocarditis

  Infection of the endothelium of the heart, most commonly affecting the heart valves, can be acute, subacute, or chronic
• Structural pathologies increasing the risk of endocarditis

  • Valvular heart disease
  • Congenital heart disease
  • Hypertrophic cardiomyopathy
  • Prosthetic heart valves
  • Implantable cardiac devices (e.g., pacemakers)
• Investigations for infective endocarditis

  1. Blood cultures are essential before starting antibiotics

  2. Echocardiography is the usual imaging investigation
• Presenting symptoms of infective endocarditis

  • Fever
  • Fatigue
  • Night sweats
  • Muscle aches
  • Anorexia (loss of appetite)
• Risk factors for infective endocarditis

  • Intravenous drug use
  • Structural heart pathology
  • Chronic kidney disease
  • Immunocompromised
  • History of infective endocarditis
• Key examination findings of infective endocarditis

  • New or “changing” heart murmur
  • Splinter haemorrhages
  • Petechiae
  • Janeway lesions
  • Osler’s nodes
  • Roth spots
  • Splenomegaly
  • Finger clubbing
• Causes of infective endocarditis

  • Staphylococcus aureus
  • Streptococcus (notably the viridans group of streptococci)
  • Enterococcus (e.g., Enterococcus faecalis)
  • Rarer causes include Pseudomonas, HACEK organisms, and fungi
• Transoesophageal echocardiography (TOE)


  • More sensitive and specific than transthoracic echocardiography
• Minor criteria for infective endocarditis

  • Predisposition
  • Fever above 38°C
  • Vascular phenomena
  • Immunological phenomena
  • Microbiological phenomena
• The gap between repeated blood culture sets may have to be shorter if antibiotics are required more urgently (e.g., sepsis)
• Diagnosis of infective endocarditis using Modified Duke Criteria

  Requires either one major plus three minor criteria or five minor criteria
• Indications for surgery in infective endocarditis

  1. Heart failure relating to valve pathology

  2. Large vegetations or abscesses

  3. Infections not responding to antibiotics
• Mainstay of treatment for infective endocarditis

  • Intravenous broad-spectrum antibiotics (e.g., amoxicillin and optional gentamicin)
• NICE guidelines (last updated in 2016) do not routinely recommend antibiotics for dental and non-dental procedures as prophylaxis of infective endocarditis. However, it is still considered on a case-by-case basis in those at particularly high risk
• Major criteria for infective endocarditis

  • Persistently positive blood cultures
  • Specific imaging findings
• Management of infective endocarditis

  Patients require admission and are managed by the relevant specialist team (e.g., the infective endocarditis or infectious diseases team)
• Imaging investigation for infective endocarditis

  Echocardiography is the usual imaging investigation
• Antibiotics are typically continued for at least 4 weeks for patients with native heart valves and 6 weeks for patients with prosthetic heart valves
• Special imaging investigations for patients with prosthetic heart valves

  • 18 F-FDG PET/CT
  • SPECT-CT
  • Modified Duke Criteria
• Blood culture sampling

  Three samples recommended, usually separated by at least 6 hours and taken from different sites
• Patients at higher risk are advised to take good care of their oral health to reduce the risk of infective endocarditis
• Infective endocarditis has a high mortality rate. Key complications include heart valve damage, heart failure, emboli, and glomerulonephritis