A 72-year-old man with ischemic cardiomyopathy and left-ventricular ejection fraction of 15% had an cardioverter-defibrillator implanted five years ago for primary prevention of sudden cardiac death. He was brought to the emergency department by his daughter who noticed erythema and swelling over the generator pocket site. His temperature is 100.1° F. Vital signs are otherwise normal and stable.
What are the best initial and definitive management strategies for this patient?
When should a cardiac implanted electronic device (CIED) infection be suspected?
CIED infections generally present in one of two ways: as a local generator pocket infection or as a systemic illness.1 Around 70% of CIED infections present with findings related to the generator pocket site. Findings in such cases include pain, swelling, erythema, induration, and ulceration. Systemic findings range from vague constitutional symptoms to overt sepsis. It is important to note that systemic signs of infection are only present in the minority of cases. Their absence does not rule out a CIED infection.1,2 As such, hospitalists must maintain a high index of suspicion in order to avoid missing the diagnosis.
Unfortunately, it can be difficult to distinguish between a CIED infection and less severe postimplantation complications such as surgical site infections, superficial pocket site infections, and noninfected hematoma.2
What are the risk factors for CIED infections?
The risk factors for CIED infection fit into three broad categories: procedure, patient, and pathogen.
Procedural factors that increase risk of infection include lack of periprocedural antimicrobial prophylaxis, inexperienced physician operator, multiple revision procedures, hematoma formation at the pocket site, and increased amount of hardware.1
Patient factors center on medical comorbidities, including congestive heart failure, diabetes mellitus, chronic kidney disease, immunosuppression, and ongoing oral anticoagulation.1
The specific pathogen also plays a role in infection risk. In one cohort study of 1,524 patients with CIEDs, patients with Staphylococcus aureus bacteremia ended up having confirmed or suspected CIED infections in 54.6% of cases, compared with just 12.0% of patients who had bacteremia with gram-negative bacilli.3
Which bacteria cause most CIED infections?
The vast majority of CIED infections are caused by gram-positive bacteria.1,4 An Italian study of 1,204 patients with CIED infection reported that pathogens isolated from extracted leads were gram-positive bacteria in 92.5% of infections.4 Staph species are the most common pathogens. Coagulase-negative staphylococcus and Staphylococcus aureus accounted for 69% and 13.8% of all isolates, respectively. Of note, 33% of CoNS isolates and 13% of S. aureus isolates were resistant to oxacillin in that study.4
Which initial diagnostic tests should be performed?
Patients should have two sets of blood cultures drawn from two separate sites, prior to administration of antibiotics.1 Current guidelines recommend against aspiration of a suspected infected pocket site because the sensitivity for identifying the causal pathogen is low while the risk of introducing infection to the generator pocket is substantial.1 In the event of CIED removal, pocket tissue and lead tips should be sent for gram stain and culture.1
Do all patients require a transesophageal echocardiogram?
Guidelines recommend a transesophageal echocardiogram (TEE) if suspicion for CIED infection is high based on positive blood cultures, antibiotic initiation prior to culture collection, ongoing systemic illness, or other suggestive signs.1,2 Positive transthoracic echocardiogram findings (for example, a valve vegetation) do not obviate the need for TEE because of the possibility of other relevant complications (including endocarditis and perivalvular extension) for which TEE has a greater sensitivity.1
What is the approach to antimicrobial therapy?
Since most infections involve staphylococcus species, initial empiric antimicrobial therapy should cover both oxacillin-sensitive and oxacillin-resistant strains. Thus, intravenous vancomycin is an appropriate initial choice.1 Culture and sensitivity results should then guide specific therapy decisions.1 Table 1 provides a summary of strategies for antimicrobial selection and duration.
Should all patients undergo complete device removal?
All patients with CIED infection require complete device removal, even if the infection is suspected to be confined to the generator pocket and blood cultures remain negative.2 Patients with superficial or surgical site infections without CIED infection do not require complete device removal. Rather, those cases can be managed with a 7- to 10-day course of oral antimicrobials.1
After device removal, what is the appropriate timing for installing a new device?
The decision to implant a replacement device is often made with input from infectious disease and cardiac electrophysiology experts. The decision must consider both infection and device-related concerns. Importantly, repeat blood cultures must be negative, and any infection in the pocket site should be controlled prior to installing a new device.2