What are the diagnostic criteria for infective endocarditis?

From the Guidelines

The diagnosis of endocarditis should be based on the modified Duke criteria, which categorizes patients as having definite, possible, or rejected endocarditis based on major and minor criteria, as outlined in the 2015 American Heart Association scientific statement 1. The modified Duke criteria include major criteria such as positive blood cultures for typical organisms (e.g., viridans streptococci, Staphylococcus aureus, or HACEK organisms) and evidence of endocardial involvement on echocardiography (vegetation, abscess, or new valvular regurgitation) 1. Some key points to consider when applying the modified Duke criteria include:

• Major criteria: positive blood cultures, evidence of endocardial involvement on echocardiography
• Minor criteria: predisposing heart conditions, fever above 38°C, vascular phenomena, immunologic phenomena, positive blood cultures not meeting major criteria
• Definite endocarditis: 2 major criteria, 1 major plus 3 minor criteria, or 5 minor criteria
• Possible endocarditis: 1 major plus 1 minor criterion, or 3 minor criteria
• Rejected endocarditis: firm alternative diagnosis, resolution of IE syndrome with antibiotic therapy, no pathological evidence of IE at surgery or autopsy Echocardiography, preferably transesophageal for better sensitivity, is essential for evaluation, and multiple blood cultures should be drawn before starting antibiotics 1. Early diagnosis is crucial as untreated endocarditis has high mortality, and empiric antibiotic therapy should be initiated promptly after blood cultures are obtained in highly suspicious cases while awaiting definitive diagnosis 1.

From the Research

Diagnosis of Endocarditis

The diagnosis of endocarditis involves several criteria, including:

• Blood cultures: 3 blood cultures should be drawn, and they should be kept for 5 days before starting intravenous antibiotic therapy 2
• Imaging tests:
  • Chest X-ray
  • Electrocardiogram
  • Echocardiography, preferably transoesophageal 2
  • Echocardiography should be performed as soon as the diagnosis of endocarditis is suspected, and repeated if initial results are negative but suspicion persists 3
• Clinical suspicion: Echocardiographic screening should only be used in patients with a reasonable clinical suspicion of endocarditis, and not as a common tool for fever 3

Diagnostic Considerations

• The use of echocardiography is crucial in the diagnosis and management of endocarditis, and it should focus on the correct identification of endocarditis lesions and associated complications 3
• The diagnosis of endocarditis can be delayed due to negative echocardiography findings early in the disease course, highlighting the need for repeated echocardiography in high-risk patients 3
• A multidisciplinary approach, including an "endocarditis team", is recommended for the diagnosis and management of endocarditis, incorporating multimodality imaging and echocardiography 3