Cardiac Device and Infection : What we know and how to Prevent ?
Cardiac implantable electronic devices (CIEDs) are being
used more and more often nowadays. Indications have grown, and access to
implantation facilities has increased as well. These devices are often
lifesaving, and they can be associated with many other benefits. However, as
with any medical procedure, complications can occur. In fact, CIED infection is
a prevalent complication that can cause high morbidity and can even lead to
death. It is important that most clinicians be familiar with signs and symptoms
associated with CIED infection as early diagnosis and treatment lead to better
outcomes. Nonetheless, the prevention of such infections remains the
cornerstone in the management of CIED-related infections. In this paper, we
will review in detail the most significant risk factors that can lead to CIED
infection. We will also explore the different available tools that can help
decrease the incidence of this complication. In addition, we will summarize the
different treatment modalities and the major prevention methods.
Bacterial inoculation often occurs as a result of bacterial
colonisation of the operative site at time of CIED implantation. Staphylococcus
species from the skin, especially, may contaminate the wound, likely during
pocket formation, and later cause pocket infection and/or erosion. Most
investigators concur that the majority of infections seen within the first year
are attributed to this early colonisation and the formation of biofilm on
device surfaces. Later, pocket erosion may also be caused by operative
contamination and biofilm formation. Bacteria in biofilm are protected from
killing by host defences and antimicrobial agents. Secondary seeding of the
CIED may also occur, especially in Staphylococcus aureus bacteraemia. Thus,
removal of the entire device is necessary when treating CIED infections.
KEY CLINICAL POINTS ( ADAPTED BY NEJM)
Infections Related to Cardiovascular Implantable Electronic
Devices
The rate at which cardiovascular implantable electronic
devices (CIEDs) are being implanted has been increasing, with an associated
increase in the number of CIED infections.
Common risk factors for CIED infections include
complications involving the generator pocket site (hematoma and poor wound
healing), revision or replacement of the device, and renal failure.
Staphylococcus species account for the majority of CIED
infections.
Complete removal of the device is required for cure, even
when signs of infection are limited to the generator pocket site, and should be
performed at a medical center with expertise in lead extraction.
Antibiotic therapy is also given for up to 2 weeks (longer
if there is evidence of endocarditis).
Perioperative antibiotic prophylaxis is effective in
reducing the risk of CIED infection.
What are the most common microbial causes of ICED infection?
Staphylococci (and Gram-positive bacteria in general) cause
the majority (68%–93%) of infections.
Gram-negative bacteria cause fewer than 18% of infections.
Approximately 15% of ICED infections are culture negative.
The microbiology of ICED infections is relevant to the
pathogenesis of infection and the selection of both antimicrobial prophylaxis
and empirical treatment regimens. Eighteen studies that included at least 100
patients were reviewed. Despite considerable heterogeneity in the design of
studies, the microbial epidemiology of ICED infections was found to be
remarkably consistent. Gram-positive bacteria were by far the most commonly
isolated microorganisms (from 67.5% of patients to 92.5% of isolates across ten
studies reporting the proportion of Gram-positives),with CoNS the most
consistently isolated bacteria followed closely by Staphylococcus aureus.
Gram-negative bacilli were isolated in 1%–17% of patient episodes (6%–10.6% of
isolates in studies using the total number of isolates as the denominator).
Fungal infection is uncommon, occurring in no more than 2% of patients. The
proportion of patients with polymicrobial infection was reported in seven
studies and ranged from 2% to 24.5%. Twelve studies reported the proportion of
patients with clinical infection but negative cultures, which ranged from 12%
to 49% of patients.
PREVENTION
The increasing rate of CIED infection has prompted a
reevaluation of the usual insertion practices and an examination of novel
interventions (discussed below). A meta-analysis of seven randomized trials
suggested that antibiotic prophylaxis given at the time of permanent pacemaker
insertion significantly reduced the infection rate (pooled odds ratio, 0.26;
95% confidence interval, 0.10 to 0.66); however, the individual trials were
underpowered, included a variety of penicillin and cephalosporin regimens, and
yielded inconsistent results.2 Still, the overall finding that systemic
perioperative antibiotic prophylaxis was beneficial is consistent with the
results of two case–control studies,a large, prospective registry, and a
retrospective population-based study. Cefazolin prophylaxis was used
predominantly in one of the case–control studies; unidentified beta-lactam
antibiotics were used in the other case–control study and for most of the
patients included in the large, prospective registry.
A large, randomized, double-blind, placebo-controlled trial
of cefazolin for prophylaxis was stopped early (after enrollment of 649
patients, with a planned total enrollment of 1000 patients) because an interim
data analysis showed substantial benefit. The incidence of device-related
infection was significantly lower in the cefazolin group than in the placebo
group (0.63% vs. 3.28%). On multivariable analysis, hematoma formation at the
pocket site and the lack of perioperative cefazolin use were independent
predictors of device-related infection.
The presence of a CIED is not considered an indication for
systemic antibiotic prophylaxis for invasive procedures. Evidence to suggest
that transient bacteremia associated with dental, gastrointestinal, or
genitourinary procedures can result in CIED infections is lacking. Moreover,
staphylococci, which are the most common microbiologic causes of CIED
infections, are infrequently associated with the transient bacteremia related
to these procedures.
Patients receiving more complex devices for an expanding
list of indications are usually ill with multiple coexisting conditions that
affect various organ systems.Therefore, extensive training in surgical
techniques, including pocket formation and wound management to diminish the
risk of complications, is an important component of electrophysiology
fellowship programs. In addition, the implementation of a comprehensive
infection prevention and control program would be expected to reduce the rate
of CIED infection.
