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Cardiac implantable electronic device infection

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ABSTRACT

Increasing numbers of patients with cardiac disease have improved quality of life and longevity as a result of cardiac implantable electronic devices (CIEDs). CIED infections can involve the generator pocket, bloodstream, or cardiac structures and occur in about 0.5% of de novo CIED implants and approximately 2% of CIED replacements. Prompt diagnosis of CIED infection is beneficial to the success of antibiotic therapy and subsequent device removal to resolve the infection. Measures to prevent CIED infections include assessment of the indication and patient status, strict sterile surgical techniques, preoperative antibiotics, and adequate homeostasis. New surgical methods and CIED devices may also lead to reduction in CIED infections. Further research is needed to better quantify the incidence of CIED, risk factors, and efficacy of surgical techniques to prevent infections.

KEY POINTS

  • CIED use is increasing, as are the number of CIED infections, which are associated with significant morbidity and mortality.
  • Prompt diagnosis of CIED infection allows for early management with antibiotics and device removal, which is typically needed for resolution of the infection.
  • Prevention of CIED infection is an important strategy, and more research is needed to inform the incidence of CIED infection, risk factors, and devices and techniques to minimize the risk of infection.


 

References

Cardiac implantable electronic devices (CIEDs) have become common tools to improve the quality of life and longevity of patients with cardiac disease over the last few decades.1–4 CIEDs include implantable cardioverter defibrillators (ICDs), permanent pacemakers, biventricular pacemakers providing cardiac resynchronization therapy with or without a defibrillator, subcutaneous ICDs, and implantable loop recorders. With increasing approved indications, the number of CIEDs implanted each year continues to grow. This, paired with the aging population of patients receiving devices and their medical complexity, has led to a corresponding increase in device-related complications.2,3 One of the most serious complications is CIED infection, which leads to significant morbidity and death. These infections also represent a significant cost burden to the healthcare system, with treatment costs for a CIED infection estimated at over $146,000 in 2008.5

SCOPE OF THE PROBLEM

More than half a million permanent pacemakers and ICDs are implanted each year in the United States, with more than 4 million implanted between 1993 and 2008.5 The risk of infection is 0.5% to 1%, for a first-time implantation and 1% to 5% for a device replacement or upgrade.1,2,5–9 These infections can involve the generator pocket, bloodstream, or cardiac structures, leading to infective endocarditis.10 The timing of CIED infection appears to be bimodal in distribution: early infections usually occur as a result of the implantation procedure itself, whereas late infections occur in patients who are generally unwell or because of an insidious process that eventually crosses a threshold of clinical significance.3,11,12

Incidence and risk factors

Klug et al13 investigated the incidence rate and risk factors of CIED infection prospectively in a large cohort of patients from 44 centers who underwent CIED implantation. Of 6,319 procedures, 4,465 were first implants and the other 1,854 were a replacement or revision; 42 patients (0.68%) developed CIED infection by 12 months after the procedure, and the incidence of infection in replacement or revision cases was nearly twice the rate found in first implants.13 Risk factors for CIED infection included renal failure, heart failure, diabetes, and fever within last 24 hours before CIED implantation.14 The Implantable Cardiac Pulse Generator Replacement (REPLACE) registry found the 6-month incidence rate of CIED infection to be 1.4% after CIED replacement.6

Recently, there has been concern that the rate of newly infected CIEDs has outpaced the rate of newly implanted ones.5,15 Voigt et al15 reported a 12% increase in the rate of CIED implantation from 2004 to 2006 and an out-of-proportion 57% increase in the rate of CIED infection. A review from 2011 confirmed these findings, showing the annual CIED implantation incidence increased an average of 4.7% per year between 1993 and 2008.5 This was probably driven by clinical trials that broadened the indications for ICD implantation for primary prevention.16–19 Between 1993 and 2008, the rate of newly implanted devices increased by 96%, while the rate for newly infected CIEDs increased by 210%; the majority of this increase occurred after 2004.5 The study showed that comorbidities in patients receiving CIEDs increased sharply starting in 2004—alluding to the contribution of comorbid medical conditions such as renal failure, respiratory failure, heart failure, and diabetes to infection risk.5

However, a major obstacle to defining the true incidence rate of CIED infection is the lack of a clear denominator. CIED infection is not limited to the first few months after implantation. In fact, over half of these patients present more than 1 year after the last CIED intervention.12 Therefore, the number of patients at risk continues to grow each year and includes patients who underwent implantation that year or before, making it very difficult to compare infection rates. Additionally, the lack of a clear definition of CIED infection and the variations in duration of follow-up in different studies make it difficult to accurately assess the incidence of CIED infection.

PATHOGENESIS

Pathogens identified in 816 patients with lead extraction or device removal for CIED infection
A CIED can become infected at the time of implantation or pocket revision. The infection can then track along the endovascular portion of the leads resulting in endovascular infection and possibly endocarditis. A CIED can also become infected as a result of the hematogenous seeding of the leads or pocket during an episode of bacteremia. Most of these infections (70%) are caused by staphylococcal species, and many are becoming resistant to methicillin.12 Other species include gram-negative organisms (9%), enterococci (4.2%), streptococci (2.5%), and fungi (1%) (Table 1). Despite clear evidence of clinical CIED infection, the cultures remain negative in about 13% of cases, perhaps because of the unfortunately common practice of starting antibiotic therapy before obtaining cultures or because of the need to incubate culture samples for a longer duration.12 A longer incubation time is particularly important for infections involving Proprionibacterium acnes, an aerobic gram-positive rod commonly associated with acne vulgaris.20

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