The prompt diagnosis of infective endocarditis is important as the condition is treatable but will almost always prove fatal if left untreated.
Diagnostics, treatment and partly also follow-up takes place within specialized care in collaboration with different specialties (cardiologist, throracic surgeon, infectious disease physician and, if needed, other specialists, such as a psychiatrist).
Factors predisposing to endocarditis are
a history of severe valvular disease
prosthetic heart valve
congenital heart disease (e.g. aortic stenosis, bicuspid aortic valve, septal defect, coarctation of the aorta)
a history of endocarditis
foreign body in the cardiovascular system
haemodialysis
immunosuppression
bad condition of the teeth
use of intravenous illegal drugs.
Should be suspected especially in febrile patients with a factor predisposing to endocarditis, bacteraemia and
a new heart murmur on auscultation or
clinical signs matching those seen in septic emboli(e.g. in the brain, lungs or skin)
the infection focus is unclear.
Diagnosis is based on the clinical picture, a positive blood culture result (in 80-90% of patients with endocarditis) and echocardiography.
In order to rule out endocarditis, echocardiography is indicated for most patients with sepsis caused by Staphylococcus aureus or candida.
Definition and epidemiology
A microbial infection involving the heart valve structures and endocardial surfaces
The most common causative agents are streptococci, staphylococci and enterococci. Also many other microbes can cause endocarditis.
The clinical presentation may be that of an acute aggressive septic infection, or the disease may be subacute and less severe (fluctuating low-grade fever).
Staphylococcus aureuscauses an acute clinical picture.
Prolonged fever is the main symptom if Streptococcus viridans is the causative agent.
Prosthetic valve endocarditis may also be caused by less pathogenic microbes, such as Staphylococcus epidermidis and fungi, leading to milder symptoms.
The development of infective endocarditis usually requires the presence of bacteraemia.
A clear history of heart disease is not demonstrable in a significant proportion of acute endocarditis cases.
Bacteraemia is often transient and asymptomatic. Only a small proportion of patients have undergone a preceding procedure that would have predisposed them to bacteraemia.
The following patient groups have an increased risk for endocarditis:
patients with prosthetic heart valves
a history of endocarditis
uncorrected congenital heart defect
patients undergoing haemodialysis
immunocompromised individuals
intravenous drug abusers
persons with poor dental hygiene.
Among the elderly and those with several comorbidities, endocarditis with an atypical clinical picture may easily remain undiagnosed.
Endocarditis in intravenous drug abusers, especially in tricuspid valve, is on the increase in some areas.
Heart murmur is audible in 85% of patients at some stage of the disease; however, an absence of a murmur does not exclude endocarditis.
The signs and symptoms may be manifold; fever is the most common symptom.
The clinical picture may sometimes be confusingly mild and fever may have persisted for several months.
Other symptoms may include metastatic abscesses on body organs or on the skin, splenomegaly, glomerulonephritis, joint symptoms, malaise, weakness, weight loss or night sweats as well as neurological symptoms resulting from embolisation.
Petechiae on the skin, mucous membranes and under the nails (rare)
Cardiac insufficiency due to severe regurgitation through the infected valve
Recurrent “flu” requiring antibiotic treatment but with no focal symptoms
Diagnosis
Based on transoesophageal echocardiography and repeated blood cultures taken before the introduction of treatment.
In echography, the findings may include vegetation and/or new valvular regurgitation, partial avulsion of the prosthetic heart valve (leading to paravalvular leak) or abscess.
A normal echocardiogram, however, does not totally rule out the possibility of endocarditis.
Culture negative endocarditis poses a diagnostic problem.
Three to four sets of blood cultures (aerobic bottle paired with an anaerobic one) should be drawn about 30 minutes apart before antimicrobial medication is started.
No need to coincide with a temperature spike
In acute septic endocarditis, it is usual to accept only two cultures collected 30 minutes apart.
Antimicrobial therapy may render blood cultures negative for a non-specified time period.
It is not always possible to reach a definitive diagnosis, and in order to err on the side of caution it may also be necessary to treat uncertain cases of endocarditis with long courses of intravenous antimicrobials.
See also Prolonged fever in the adult Vaccinations.
Treatment and follow-up
A long course of antimicrobial therapy (usually 4-6 weeks) targeted at the infecting bacterium
Follow-up blood cultures during treatment until the clearance of bacteraemia is confirmed.
The need for surgical intervention should be evaluated immediately after the diagnosis is confirmed. About half of patients require valvular surgery either during the acute phase or later on.
Indications for surgical intervention, usually prosthetic valve surgery, include: worsening cardiac insufficiency or progressing valve regurgitation, paravalvular abscess, recurrent emboli or persistently positive blood cultures despite appropriate medication.
Prosthetic valve endocarditis and endocarditis caused by Staphylococcus aureus or fungi often require surgical intervention.
Endocarditis may recur after the antimicrobial therapy is completed (incidence 2-6%). Regular initial follow-up is necessary.
Monitoring the appearance of inflammatory symptoms, repeated echocardiograms and laboratory tests
Blood cultures if fever develops
After endocarditis, the patient should regularly visit a dentist and maintain good oral and skin health.
Prognosis depends, among others, on the aetiological microbial agent, underlying heart disease, complications and treatment.
The average mortality rate of treated endocarditis is about 15-30%.
Fungal endocarditis usually carries a higher mortality rate than bacterial endocarditis.
References
Habib G, Lancellotti P, Antunes MJ, et al. 2015 ESC Guidelines for the management of infective endocarditis: The Task Force for the Management of Infective Endocarditis of the European Society of Cardiology (ESC). Endorsed by: European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Nuclear Medicine (EANM). Eur Heart J 2015;36(44):3075-3128. [PubMed]