From the Guidelines
The diagnostic criteria for infective endocarditis are based on the modified Duke criteria, which include major and minor criteria, as outlined in the most recent guidelines from the European Society of Cardiology (ESC) in 2015 1.
Major Criteria
The two major criteria are:
- Positive blood cultures (at least two separate cultures showing typical organisms for endocarditis such as viridans streptococci, Streptococcus gallolyticus, HACEK group, Staphylococcus aureus, or community-acquired enterococci)
- Evidence of endocardial involvement (echocardiogram showing a vegetation, abscess, or new valvular regurgitation)
Minor Criteria
Minor criteria include:
- Predisposing heart conditions
- Intravenous drug use
- Fever above 38°C
- Vascular phenomena (emboli, septic infarcts, mycotic aneurysms)
- Immunologic phenomena (glomerulonephritis, Osler's nodes, Roth spots)
- Positive blood cultures not meeting major criteria
Diagnosis
Definite endocarditis is diagnosed with either:
- Two major criteria
- One major plus three minor criteria
- Five minor criteria Possible endocarditis is diagnosed with one major plus one minor criterion or three minor criteria.
Recommendations
When suspecting endocarditis, obtain at least three sets of blood cultures before starting antibiotics, and perform both transthoracic and transesophageal echocardiography 1. Early diagnosis is crucial as delayed treatment can lead to severe complications including heart failure, embolic events, and death. The most recent guidelines from the American College of Radiology in 2021 also emphasize the importance of imaging in the diagnosis and management of infective endocarditis 1.
From the Research
Diagnostic Criteria for Infective Endocarditis
The diagnostic criteria for infective endocarditis have evolved over time, with the Duke criteria being the most widely accepted and utilized today 2, 3, 4. The key components of the Duke criteria include:
- Major criteria:
- Typical blood culture results
- Positive echocardiogram
- Minor criteria:
- Predisposition (e.g., heart condition, intravenous drug use)
- Fever
- Vascular phenomena
- Immunologic phenomena
- Suggestive echocardiogram
- Suggestive microbiologic findings
Comparison with von Reyn Criteria
The Duke criteria have been shown to be more sensitive and specific than the von Reyn criteria, which were previously widely used 2, 4. The von Reyn criteria relied mainly on clinical, microbiological, and histopathological criteria, but had a lower sensitivity (around 30-60%) and specificity compared to the Duke criteria.
Limitations and Modifications
While the Duke criteria are highly sensitive and specific, there are still limitations and challenges in diagnosing infective endocarditis, particularly in cases of culture-negative endocarditis 5, 6. Modifications to the Duke criteria have been proposed, including the addition of unspecific inflammatory parameters (e.g., C-reactive protein) and positive Q-fever serology as major criteria 6.
Clinical Application
The Duke criteria are currently the most sensitive tool in the diagnosis of infective endocarditis and have been widely adopted in clinical practice 3, 4, 6. They can help shorten the time to diagnosis and improve clinical outcomes. However, clinical judgment and expertise are still essential in applying these criteria and making accurate diagnoses 6.