BONOW
ET AL., ACC/AHA TASK FORCE REPORT
JACC Vol. 32, No. 5, November 1998:1486-1588
ACC/AHA
Guidelines for the Management of Patients With Valvular
Heart Disease
IV.
Evaluation and Management of Infective Endocarditis
Clinical
suspicion of infective endocarditis may be raised by
the presence of fever and other systemic symptoms coupled
with physical findings such as Osler's nodes, petechiae,
Janeway lesions, Roth spots, splenomegaly, and a cardiac
murmur. At present, these physical signs are less commonly
encountered, and definitive diagnosis is made by demonstrating
an offending organism by blood culture. Three sets of
blood cultures, obtained at intervals >1 hour
within the first 24 hours, is the norm; however, in
selected patients, 5 to 6 sets of blood cultures may
be needed, and some patients have culture-negative endocarditis
(see below). Additionally, echocardiography has provided
an important tool for recognizing both valvular structural
abnormality and vegetations. The yield for visualization
of vegetations for transthoracic echocardiography is
~60% to 77% and increases to ~96% with transesophageal
imaging. The latter technique usually provides better
delineation of valvular anatomy and function. This is
especially the case for evaluation of prosthetic valves
(488). However, the
absence of vegetations on echocardiography does not
exclude the diagnosis of infective endocarditis, and
the complete clinical condition should be considered.
Criteria
for the diagnosis of infective endocarditis were proposed
by Von Reyn and colleagues (489)
with the results of blood cultures, clinical signs,
and symptoms. Subsequently, the Duke criteria were developed
to include evidence of endocardial involvement (490).
Table 21 shows the modified
Duke criteria by Bansal (27).
A.
Antimicrobial Therapy
Antimicrobial
therapy in endocarditis is guided by identification
of the causative organism. Eighty percent of cases of
endocarditis are due to streptococci and staphylococci.
The majority of native valve endocarditis is caused
by Streptococcus viridans (50%) and Staphylococcus
aureus (20%). The latter organism is also the most
frequent organism in endocarditis resulting from intravenous
drug abuse. Eighty percent of tricuspid valve infection
is by S aureus; this organism is also a frequent
cause of infective endocarditis in patients with insulin-dependent
diabetes mellitus. With prosthetic valve endocarditis,
a wide spectrum of organisms can be responsible within
the first year of operation. However, in "early"
prosthetic valve endocarditis, usually defined as endocarditis
during the first 2 months after surgery, Staphylococcus
epidermidis is the frequent offending organism.
Late-onset prosthetic valve endocarditis follows the
profile of native valve endocarditis: ie, streptococci
(viridans) and staphylococci. Enterococcus
faecalis and Enterococcus faecium account
for 90% of enterococcal endocarditis, usually associated
with malignancy or manipulation of the genitourinary
or gastrointestinal tract. Gram-positive and gram-negative
bacilli are relatively uncommon causes of endocarditis.
In recent years, the HACEK group of organisms (Haemophilus,
Actinobacillus, Cardiobacterium, Eikenella, and
Kingella species) have become important causes
of endocarditis. They cause large vegetations (>1
cm), large-vessel emboli, and congestive heart failure.
They should be considered along with fungal endocarditis
when large vegetations are noted. Fungi, especially
candida, are important causes of endocarditis
in patients with prosthetic valves, compromised immune
systems, and intravenous drug abuse. The AHA recommendations
for antimicrobial regimens are given in Tables
22, 23, 24,
25, 26,
27 (491).
B.
Culture-Negative Endocarditis
Culture-negative
endocarditis most frequently (62%) results from prior
antibiotic treatment before blood cultures were drawn
(493,494).
The other reasons for negative blood cultures are infections
due to Candida; Aspergillus; or fastidious, slow-growing
organisms (492) and
noninfective endocarditis such as Libman-Sacks endocarditis
in patients with systemic lupus erythematosus. A proposed
regimen for culture-negative, presumed bacterial endocarditis
(492) is shown in Table
28.
C.
Endocarditis in HIV-Seropositive Patients
Endocarditis
in patients who are HIV-seropositive usually occurs
as a complication of injection drug use or long-term
indwelling central catheters. S aureus is the
most frequent pathogen. When endocarditis is not related
to intravenous drug use, right- and left-sided valves
are equally involved. Intravenous drug use is the most
common cause of tricuspid valve endocarditis. Endocarditis-related
mortality in patients with AIDS exceeds that of HIV-positive
patients without AIDS. Thus, it is recommended that
endocarditis in patients with AIDS be treated with maximum-duration
antibiotic regimens (491).
D.
Indications for Echocardiography in Endocarditis
Echocardiography
is useful for detection and characterization of the
hemodynamic and pathological consequences of infection.
These consequences include valvular vegetations; valvular
regurgitation; ventricular dysfunction; and associated
lesions such as abscesses, shunts, and ruptured chordae
(495). The indications
for transthoracic and transesophageal echocardiography
are discussed in the ACC/AHA Guidelines for the Clinical
Application of Echocardiography (2).
Transesophageal imaging is more sensitive in detecting
vegetations than transthoracic imaging (488,496).
Echocardiography may be useful in the case of culture-negative
endocarditis (497)
or the diagnosis of a persistent bacteremia whose source
remains unidentified after appropriate evaluation (2).
Recommendations
for Echocardiography in Infective Endocarditis: Native
Valves
Recommendations
for Echocardiography in Infective Endocarditis: Prosthetic
Valves
E.
Outpatient Treatment
Patients
with penicillin-susceptible S viridans endocarditis
who are hemodynamically stable, compliant, and capable
of managing the technical aspects of outpatient therapy
may be candidates for a single daily-dose regimen of
ceftriaxone (491).
Recent clinical reports suggest that right-sided endocarditis
caused by S aureus in intravenous drug users
may be amenable to a short 2-week course of therapy
(498,499).
Monotherapy with ceftriaxone or combination therapy
with an aminoglycoside has been tried as an outpatient
therapeutic option (500).
However, more data are needed to determine with more
certainty whether such outpatient regimens have therapeutic
effectiveness equivalent to the established 4-week regimens.
F.
Indications for Surgery in Patients With Active Infective
Endocarditis
Surgery
is indicated in patients with life-threatening congestive
heart failure or cardiogenic shock due to surgically
treatable valvular heart disease with or without proven
infective endocarditis if the patient has reasonable
prospects of recovery with satisfactory quality of life
after the operation (442,501-525).
Surgery should not be delayed in the setting of acute
infective endocarditis when congestive heart failure
intervenes. Surgery is not indicated if complications
(severe embolic cerebral damage) or comorbid conditions
make the prospect of recovery remote.
The
indications for surgery for infective endocarditis in
patients with stable hemodynamics are less clear. Early
consultation with a cardiovascular surgeon is recommended
as soon as the diagnosis of aortic or mitral valve endocarditis
is made so that the surgical team is aware of the patient
who may suddenly need surgery. Surgery is recommended
in patients with annular or aortic abscesses, those
with infections resistant to antibiotic therapy, and
those with fungal endocarditis. It is recognized that
the presence of valvular vegetations poses a threat
of embolic events. Echocardiography, especially with
transesophageal imaging, identifies vegetations and
provides size estimation in many instances. Patients
with a vegetation diameter >10 mm have a significantly
higher incidence of embolization than those with a vegetation
diameter <10 mm (488),
and this risk appears to be higher in patients with
mitral valve endocarditis than aortic valve endocarditis.
However, operation on the basis of vegetation size alone
is controversial.
Patients
with prosthetic valves receiving warfarin anticoagulation
who develop endocarditis should have their warfarin
discontinued and replaced with heparin. This recommendation
is less related to the possibility of hemorrhagic complications
of endocarditis (526)
than the possibility of urgent surgery. If surgery is
required, the effects of warfarin will have dissipated,
and heparin can easily be reversed. Likewise, aspirin,
if part of the medical regimen, should also be discontinued.
If neurological symptoms develop, anticoagulation should
be discontinued until an intracranial hemorrhagic event
is excluded by magnetic resonance imaging or computed
tomographic scanning.
Recommendations
for Surgery for Native Valve Endocarditis*
Recommendations
for Surgery for Prosthetic Valve Endocarditis*
©
1998 American College of Cardiology and American Heart
Association, Inc. Published by Elsevier
Science Inc.
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