Diagnosis
Rubor, dolor, calor, tumor over the pacer pocket a wire infection presenting as bacteremia without a focus.
All patients with bacteremia and a CIED should get a TEE looking for infected wires. However, do not be reassured by a negative evaluation; they still have a high probability of infection especially if it is S. aureus.
Epidemiologic Risks
A pacer plus bad luck = infection.
It can have a pocket infection with or without a wire infection. "Patients with CIED pocket infection who meet systemic inflammatory response syndrome criteria and/or are hypotensive at admission are more likely to have underlying BSI and should be started on empiric antibiotics after blood cultures are obtained. If these features are absent, it may be reasonable to withhold empiric antibiotics to optimize the yield of pocket/device cultures during extraction (PubMed)."
S. aureus bacteremia has about a 30-50% chance of seeding the pacer wire. It is amazing how often I get called for S. aureus bacteremia (SAB) and the patient has a pacer and the consulting team isn't all that concerned. SAB with a pacer is a disaster.
"On univariate analysis, previous PPM infection, malignancy, long-term corticosteroid use, multiple device revisions, a permanent central venous catheter, the presence of >2 pacing leads, and a lack of antibiotic prophylaxis at the time of PPM placement were associated with an increased risk of PPM infection. A multivariable logistic regression model identified long-term corticosteroid use and the presence of >2 pacing leads versus 2 leads as independent risk factors for PPM infection. In contrast, the use of antibiotic prophylaxis prior to PPM implantation had a protective effect (PubMed)."
A PET scan would be $6000 dollar test that may help diagnose the infection; there is an interesting literature suggesting it is a great test: "Sensitivity, specificity, positive predictive value, and negative predictive value for 18FFDG PET/CT were 82%, 96%, 94%, and 87%, respectively (Pubmed)(PubMed)."
It is also a summer disease (PubMed).
An antibiotic eluting envelope at the time of insertion can decrease infections (Pubmed).
Microbiology
Skin flora (S. aureus and coagulase-negative staphylococcus) are most common, but anything can infect the pocket or the wire. It is very rare for gram-negative rods to seed a pacemaker (PubMed). Except I had this case early in my practice with Serratia. Cardiology told me I had to cure the infection since they would kill him if they took it out. Remember, this is about 1990, when I was young and stupid. So I thought to myself, the problem with a wire infection is that the organism is protected by clot, so why not give urokinase to strip off the clot and the bacteria. So I did. And the patient got quite septic with the resultant bacteremia. Eventually, the pacer was removed and he did just fine. Two take homes. 1) Don't lyse infected clot. 2) Don't believe cardiology when then say they can't remove the pacer.
For ventricular assist devices, Staphylococcus aureus, Staphylococcus, coagulase-negative, Enterococcus, and Pseudomonas aeruginosa lead the list, but others have case reports. Candida albicans was cause for those who received TPN and has a 90% mortality rate (PubMed).
Staphylococcus aureus, P. aeruginosa, or S. marcescens (PubMed) in the blood have a high likelihood of infecting the device. Other gram-negative rods are much less likely to infect a cardiac device. And yes, I know S. aureus is not a gram-negative rod.
Empiric Therapy
Given the huge rates of MRSA I start with vancomycin pending cultures, cefazolin OR nafcillin/oxacillin would also be reasonable. Local resistance patterns, as always, rule. Once the organism is identified, if bacteremic I usually treat presumptively for right-sided endocarditis.
High dose daptomycin (6-10 mg/kg/d) was used in one series (after lead removal) with good success (PubMed).
The pacer system needs to come out. In the Oxford English Dictionary, the third definition of futile is medical therapy of a pacer infection. And the longer you delay removing the device, the more likely the patient will die: "early and complete device removal was associated with improved outcomes. (PubMed)." Now, try and convince your cardiologist.
If it is a pacer pocket infection only, I change to po antibiotics 24 hours after the generator is removed. Often I continue the po until the old pocket is healed; there is always a fear, probably unfounded, that the bacteria will mysteriously transport from the old system to the new.
For ventricular assist devices, given the microbiology, vancomycin and anti-pseudomonal. Add an echinocandin if on TPN.
From the largest case series (PubMed): "The most common type of LVADIs were driveline infections (47%), followed by bloodstream infections (24% VAD related, and 22% non-VAD related). The most common causative pathogens included gram-positive cocci (45%), predominantly staphylococci, and nosocomial gram-negative bacilli (27%). Almost half (42%) of the patients were managed by chronic suppressive antimicrobial therapy. While 14% of the patients had intraoperative debridement, only 3 underwent complete LVAD removal. The average duration (±SD) of LVAD support was 1.5±1.0 years. At year 2 of follow-up, the cumulative incidence of all-cause mortality was estimated to be 43%."
Chronic suppression has a reasonable chance of keeping the infection at bay if the system cannot be removed (PubMed).
Pearls
Occasionally a cause of right-sided endocarditis. To give a rabbit endocarditis, you put a wire across the valve and make the rabbit bacteremic; most will get endocarditis as a result. Sound familiar?
Rants
You have to pull the pacemaker system, maybe just the generator if a pocket infection, but if the wires are infected they have to go as well. This is one prosthetic infection you can NEVER cure medically. The cardiologist with whine and complain about the complications and difficulties of pulling a pacer (and rightly so). And so you will try to salvage it medically. And you will fail. So bite the bullet and remove it. The risk of the infection is much higher than the risk of extraction (PubMed).
Curious Cases
Relevant links to my Medscape blog
Last Update: 06/01/19.