Fever with bacteraemia (suspected endocarditis)
Who needs echo, who needs TOE, and when to repeat it — the Duke-ISCVID imaging criteria.
Echo approach, step by step
The 2023 ESC endocarditis guideline and the Duke-ISCVID criteria make echo central to the diagnosis [136,137]. TTE first in all patients with suspected IE. TOE if TTE is negative or non-diagnostic with persisting suspicion, with prosthetic valves or devices, and in most positive TTE studies to detect local complications [136].
- TTEAll valves, devices and leads; vegetation size and mobility [136].
- ComplicationsRegurgitation, perforation, abscess, pseudoaneurysm, fistula [136].
- TOEAs indicated above [136].
- RepeatTOE after 5–7 days if the first study is negative and suspicion stays high; and at any new complication [136].
- PET-CT or cardiac CTFor suspected prosthetic valve or device IE with inconclusive echo [136].
- TTE all valves and devices
- Vegetation size and mobility
- Complications
- TOE performed or planned
- Repeat imaging planned
Causes & echo clues
| Scenario | Echo priority [136] |
|---|---|
| S. aureus bacteraemia | Echo in all; TOE in most (especially with high-risk features) |
| Streptococcal (viridans, S. gallolyticus) or enterococcal bacteraemia | Echo; low threshold for TOE |
| Prosthetic valve | TOE; PET-CT if inconclusive |
| Cardiac device | TOE for lead vegetations; PET-CT |
| Injecting drug use | Tricuspid and pulmonary valves |
| Culture-negative | Consider prior antibiotics, Bartonella, Coxiella; marantic |
Clinical pathway to the diagnosis
- Three sets of blood cultures before antibiotics[136].
- Duke-ISCVIDMicrobiological and imaging major criteria, plus minor criteria (predisposition, fever, vascular and immunological phenomena) [137].
- EchoTTE, then TOE [136].
- Complication screeningBrain imaging, abdominal imaging [136].
- Endocarditis teamSurgery decisions [136].
Clinical pearls & pitfalls
PitfallNegative TTE ≠ no endocarditis. A normal TTE with high clinical suspicion requires TOE [136].
- Lambl's excrescences and degenerative strands are common mimics. Correlate with microbiology [176].
Red flags
- Staphylococcus aureus bacteraemia — echo in all patients [136]
- Prosthetic valve or cardiac device with fever [136]
- New murmur, heart failure, conduction block or embolism [136]