Infective endocarditis — structured viva

Stem

A 61-year-old man with known mitral regurgitation has had fever for 3 weeks. Two separate blood cultures grow Streptococcus mitis, and TTE shows a 12 mm mobile vegetation on the mitral valve. This is a practice scenario.

Branch A — Diagnosis

Examiner: Does he have endocarditis by the 2023 ESC criteria?^[1]

Strong answer: Yes, definite infective endocarditis (IE).^[1] S. mitis belongs to the oral streptococci, and oral streptococci in two separate blood cultures meet the microbiological major criterion, and a lesion characteristic of IE on echocardiography meets the imaging major criterion.^[1] Two major criteria make the diagnosis definite.^[1] A temperature above 38°C would add a minor criterion, but it is not needed for the classification.^[1]

Examiner (follow-up): What is "possible IE" now?^[1]

Strong answer: One major criterion with 1 or 2 minor criteria, or 3–4 minor criteria.^[1] The older Modified Duke Criteria, still used by the 2020 ACC/AHA guideline, require 1 major and 1 minor, or 3 minor.^[2]

Examiner (follow-up): Name two other changes in the 2023 criteria.^[1]

Strong answer: E. faecalis is now a typical organism, regardless of the place of acquisition or source of infection.^[1] Embolic vascular dissemination now counts as a minor criterion even when asymptomatic and detected by imaging only.^[1] Cerebral microbleeds are not a minor criterion.^[1]

Branch B — Imaging

Examiner: TTE is already positive. Does he need transoesophageal echocardiography (TOE)?^[1]

Strong answer: Yes. TOE is recommended in suspected IE even with a positive TTE, except in isolated right-sided native valve IE with a good-quality TTE and unequivocal findings (Class I, Level C).^[1] TTE has limited ability to diagnose perivalvular complications and small vegetations, so TOE is used even after a positive TTE to document local complications.^[1]

Examiner (follow-up): When would you use CT or PET/CT?^[1]

Strong answer: Cardiac computed tomography angiography (CTA) is recommended in possible native valve endocarditis (NVE) to detect valvular lesions and confirm IE (Class I, Level B).^[1] It is also recommended in NVE or prosthetic valve endocarditis (PVE) to diagnose paravalvular or periprosthetic complications if echocardiography is inconclusive (Class I, Level B).^[1] [18F]FDG-PET/CT(A) is recommended with cardiac CTA in possible PVE, to detect valvular lesions and confirm IE (Class I, Level B).^[1] In NVE, PET/CT sensitivity is low (about 31%), so IE cannot be excluded by the absence of abnormal uptake.^[1] Brain and whole-body imaging are recommended if he has symptoms suggesting septic embolic complications, to detect peripheral lesions or add minor criteria (Class I, Level B), and may be considered to screen for peripheral lesions if he is asymptomatic (Class IIb, Level B).^[1]

Branch C — Antibiotics

Examiner: The isolate is penicillin-susceptible. What will you give?^[1]

Strong answer: Penicillin G, amoxicillin or ceftriaxone for 4 weeks in NVE (Class I, Level B), for example ceftriaxone 2 g/day intravenous (i.v.) in 1 dose or penicillin G 12–18 million units/day i.v. in 4–6 doses or continuously.^[1] For penicillin G the starting doses are the lower doses, which can be scaled up to the highest.^[1] The 2-week regimen with gentamicin is recommended only for non-complicated NVE with normal renal function (Class I, Level B), and it is not applicable to PVE.^[1]

Examiner (follow-up): From which day do you count the 4 weeks?^[1]

Strong answer: From the first day of effective antibiotic therapy (a negative blood culture if cultures were initially positive) rather than from the day of surgery. If he has surgery, a new full course starts only if valve cultures are positive.^[1]

Examiner (follow-up): Where do aminoglycosides and rifampin fit in IE generally?^[1]

Strong answer: Aminoglycosides are not recommended in staphylococcal NVE. In other conditions where they are indicated (for example resistant oral streptococci), they are given for no longer than 2 weeks and in a single daily dose; the staphylococcal PVE regimen gives gentamicin in 1 (preferred) or 2 doses.^[1] Rifampin is used only in foreign-body infection such as PVE, after 3–5 days of effective therapy once bacteraemia has cleared.^[1]

Branch D — Surgery

Examiner: On day 5 of appropriate antibiotic therapy he has a cerebellar transient ischaemic attack (TIA). Repeat TOE shows that the 12 mm mitral vegetation persists, with no aortic valve involvement, and CT brain shows no haemorrhage. Does that change the plan?^[1]

Strong answer: Yes. Urgent surgery (within 3–5 days) is recommended in mitral NVE with a persistent vegetation of at least 10 mm after one or more embolic episodes despite appropriate antibiotics (Class I, Level B).^[1] After a TIA, cardiac surgery, if indicated, is recommended without delay (Class I, Level B).^[1] Urgent surgery (within 3–5 days) is also recommended for a vegetation of at least 10 mm with another indication for surgery (Class I, Level C).^[1] Complicated IE is recommended to be managed early in a Heart Valve Centre with immediate surgical facilities and an Endocarditis Team, to improve outcomes (Class I, Level B).^[1] Because he needs surgery, intra-operative echocardiography is recommended (Class I, Level C), and, with no aortic valve vegetation, invasive coronary angiography is recommended if he is at high risk for coronary artery disease (CAD) (Class I, Level C).^[1]

Examiner (follow-up): Why act early?^[1]

Strong answer: Embolic risk is highest around the start of antibiotic treatment and falls over the first 2 weeks, so the benefit of surgery to prevent embolism may be greatest early.^[1] In the Kang trial of left-sided IE with severe valve disease and large vegetations, in-hospital death or embolism within 6 weeks occurred in 3% with surgery within 48 hours versus 23% with conventional treatment.^[4]

Examiner (follow-up): What if brain imaging had instead shown an intracranial haemorrhage?^[1]

Strong answer: After intracranial haemorrhage, ESC 2023 says delaying surgery for more than 1 month, if possible, with frequent clinical and imaging re-assessment, should be considered (Class IIa, Level C).^[1] If he were unstable from heart failure (HF), uncontrolled infection or persistent high embolic risk, urgent or emergency surgery should be considered, weighing the chance of a meaningful neurological outcome (Class IIa, Level C).^[1] Thrombolysis is not recommended in embolic stroke due to IE (Class III, Level C).^[1]

Branch E — After the acute phase

Examiner: Suppose he did not need surgery. Can he go home on oral antibiotics?^[1]

Strong answer: Possibly. Outpatient parenteral or oral treatment should be considered in left-sided IE caused by Streptococcus spp., E. faecalis, S. aureus or coagulase-negative staphylococci (CoNS) after at least 10 days of appropriate i.v. treatment.^[1] It applies only if he is clinically stable and TOE shows no abscess or valve abnormality requiring surgery (Class IIa, Level A).^[1] TOE is recommended when he is stable, before the switch (Class I, Level B).^[1] POET randomised 400 stable patients with left-sided IE caused by streptococci, E. faecalis, S. aureus or CoNS.^[3] Oral step-down was noninferior for all-cause death, unplanned cardiac surgery, embolic events or relapse of bacteraemia with the primary pathogen, from randomisation to 6 months after antibiotic treatment was completed (12.1% i.v. vs 9.0% oral).^[3]

Examiner (follow-up): What follow-up will you arrange?^[1]

Strong answer: A clinical evaluation and baseline TTE at the end of antibiotics, to monitor for secondary heart failure, repeated if his condition changes.^[1] Clinical re-assessment one or more times in the first year and yearly thereafter, depending on his individual risk profile, and inflammatory markers (white blood cell (WBC) count, C-reactive protein (CRP) and procalcitonin) early after antibiotics end, repeated when clinically indicated.^[1] ESC 2023 also encourages blood cultures within the first week after treatment ends, because of the increased risk of relapse for virulent microorganisms.^[1] TTE and/or TOE are recommended at completion of antibiotics in patients who did not have valve surgery (Class I, Level C).^[1] Education during follow-up on recurrence risk, with emphasis on dental health and based on his individual risk profile, is recommended (Class I, Level C), and he now has previous IE, a high-risk group, so prophylaxis is recommended before future dental extractions (Class I, Level B).^[1] Cardiac rehabilitation with exercise training should be considered if he is clinically stable, based on an individual assessment (Class IIa, Level C), and psychosocial support may be considered within follow-up care (Class IIb, Level C).^[1]