The European Society of Cardiology state the following should cause infective endocarditis to be suspected:
- New regurgitant heart murmur
- Embolic events of unknown origin
- Sepsis of unknown origin
- Fever in certain cases
The most frequent sign of IE is fever (up to 90% of cases)
There are often systemic symptoms
Heart murmurs are present in 85% of cases
The classic (but not necessarily common) signs associated with IE are:
The classic (but not necessarily common) signs associated with IE are:
- Roth spots
- Janeway lesions
- Osler nodes
- Splinter haemorrhages
Diagnosis is by the Modified Duke Criteria:
- Diagnosis is definite in the presence of:
- 2 major criteria or
- 1 major and 3 minor criteria or
- 5 minor criteria
- Major criteria
- Blood cultures positive for IE
- Evidence of endocardial involvement
- Echocardiography positive for IE or
- New valvular regurgitation
- Minor criteria
- Predisposition (predisposing heart condition, IVDU)
- Fever (>38C)
- Vascular phenomena (major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial haemorrhages, conjunctival haemorrhages, Janeway lesions)
- Immunologic phenomena (glomerulonephritis, Osler’s nodes, Roth’s spots, rheumatoid factor)
- Microbiological evidence that does not meet major criteria
Key investigations are therefore
- Blood cultures – 3 sets an hour apart
- Echocardiography – TTE has a sensitivity of around 46% while TOE’s sensitivity is 93%
Most cases of IE are left sided.
5-10% are right-sided and most of these are associated with IVDUs
In terms of microbiology, IE can be divided into:
1) Infective endocarditis with positive blood cultures = 85% of cases
- Commonest causative organism = streptococcus viridans
- Commonest causative staphylococcal organism on native valve = s. aureus
- Commonest causative staphylococcal organism on prosthetic valve = coagulase-negative straphylococci
- Commonest causative organism in right sided IE = s. aureus
- Third most common causative organism after strep and staph = enterococci
2) Infective endocarditis with negative blood cultures due to prior antibiotic treatment
3) Infective endocarditis frequently associated with negative blood cultures
- HACEK group = Haemophilus parainfluenzae, H. aphrophilus, H. paraphrophilus, H. influenzae, Actinobacillus actinomycetemcomi- tans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae, and K. denitrificans Brucella
- Fungi
4) Infective endocarditis associated with constantly negative blood cultures = 5% of cases
- Intracellular bacteria – coxiella burnetii, bartonella, chlamydia, tropheryma whipplei
Treatment:
- Antibiotics
- Initial empirical treatments:
- Native-valve IE and prosthetic valves >12months post surgery:
- Co-amoxiclav and gentamicin, or
- vancomycin, gentamicin and ciprofloxacin if beta-lactam allergy
- Prosthetic valves, <12 months post surgery:
- vancomicin with gentamicin and rifampin
- Treatments once bacteria is identified:
- Strep infections
- Strains susceptible to penicillin: 4 weeks of either penicillin G or amoxicillin or cefriazone
- Strains relatively resistant to penicillin: 4 weeks of penicillin or amoxicillin plus gentamicin for the first 2 weeks
- Staph infections
- On native valve: 4 to 6 weeks of flucloxacillin or oxacillin with 3 to 5 days of gentamicin
- On prosthetic valve: at least 6 weeks of flucloxacillin or oxacillin plus oral rifampin plus 2 days of gentamicin
- In case of beta lactam allergy, use vancomycin wherever a beta lactam has been listed.
- Surgery – indications include heart failure due to valve destruction and uncontrolled infection
Prognosis:
In-hospital mortality rate: 10 to 26%
Complications
- Heart failure
- Most frequent complication of IE – 50-60% of cases
- More common when IE affects the aortic valve
- Embolisms
- Occurs 20-50% of patients before antibiotics are started
- risk highest during first 2 weeks of antibiotics
- risk related to size of vegetation
- left-sided IE is most associated with embolisms to brain (=risk of stroke) and spleen
- right sided IE is most associated with PE
- Acute renal failure – around 30% of patients
- Abscess
NICE defines the following as being at increased risk of developing endocarditis:
- Acquired valvular heart disease with stenosis or regurgitation
- Valve replacement
- Structural congenital heart disease (but excluding isolated atrial septal defects, fully repaired ventricular septal defects, fully repaired patent ductus arteriosus and closure devices that are endothelialised Hypertrophic cardiomyopathy
- Previous infective endocarditis
Antibiotic prophylaxis???
- NICE doesn’t recommend antibiotic prophylaxis in any scenario.
- The European Society of Cardiology recommends prophylaxis only in:
- ‘highest risk’ patients (such as previous IE, valve replacement and some forms of congenital heart disease) and only for:
- dental procedures that perforate the oral mucosa or manipulate the gingival region (use amoxicillin, ampicillin or clindamycin)
- skin procedures involving infected skin (use cephalosporin)
- Small print gems:
- strep bovis can cause IE and is strongly associated with bowel cancer
- Libman-Sacks endocarditis is a form of endocarditis characterized by sterile fibrofibrinous vegetations, usually on the left side. It is associated with SLE.
- Marantic endocarditis, also known as non-bacterial thrombotic endocarditis, is a form of sterile endocarditis associated with a variety of inflammatory states including malignancy.
Habib, G. et al. Guidelines on the prevention, diagnosis and treatment of infective endocarditis (new version 2009). European Heart Journal. 2009; 30: 2369-2413.
Jameson, G. et al. Marantic endocarditis associated with pancreatic cancer: a case series. Case Rep Gastroenterol. 2009; 3(1): 67-71.
Jameson, G. et al. Marantic endocarditis associated with pancreatic cancer: a case series. Case Rep Gastroenterol. 2009; 3(1): 67-71.
