Risk factors for asymptomatic bacterial colonization of cardiac implantable electronic devices
Authors: Jin F , Lacour P , Parwani A , Baehr F , Schoeppenthau D , Dagres N , Boldt L H , Hindricks G , Blaschke F 
Published: May 2024

Abstract

Introduction
With broadening indications and a progressively ageing demographic, incidence of cardiac electronic implantable device (CIED) implantation increased. Despite device infection being rare, it persists as a serious complication concomitant with a high mortality rate. While extensive research on cardiac device infection (CDI) has been conducted, the incidence and clinical significance of asymptomatic bacterial CIED colonisation has not been investigated so far.

Purpose
Our study aims to elucidate potential risk factors for and investigate the clinical significance of asymptomatic bacterial CIED colonisation.

Methods and Results
In this prospective single centre study, 345 patients with no clinical signs of CIED infection underwent a generator exchange. In total, 78 pacemakers (PM), 97 implantable cardiac defibrillators (ICD), 67 cardiac resynchronisation therapy devices (CRT), 1 baroreceptor stimulator, as well as 102 implantable loop recorders were sonicated to determine the presence of adherent microorganisms (biofilms). Intraoperative swabs were collected in 329 patients. For statistical analysis, detection of ≥1 colony forming units (CFU) during sonication was considered a significant level of bacterial colonisation. The ≥50 CFU threshold was established in order to examine risk factors relevant for higher levels of bacterial colonization. 88 CIED (25.5%) showed bacterial colonisation ≥1 CFU while 44 CIED (12.8%) were colonised with ≥50 CFU.
Multivariate analysis revealed male gender as independent risk factor for both ≥1 CFU (p&lt;0.001; OR 7.73, CI 2.84-21.04) and ≥50 CFU (p&lt;0.001; OR 12.14, CI 2.79-52.78). and immunosuppressive medication (p=0.018; OR 3.31; CI 1.23-8.92) as independent risk factor identified for ≥50 CFU colonisation. For both cutoffs, Cutibacterium acnes emerged as the most frequently detected bacterium during sonication, followed by coagulase negative Staphylococci (CoNS) with Staphylococcus epidermidis being the most common within this CoNS group. During the follow-up (384.5 +/- 480.6 days), 287 patients showed absence of CDI (53 patients lost to follow-up). Of the five patients with CDI, one exhibited concordant results between sonication, swab, and blood culture for Cutibacterium acnes, one presented with partially concordant results, whereas the other three showed varying degrees of disconcordance between index event microbiological results and subsequent CDI pathogens.

Conclusion
Remarkably, 27.2% of CIEDs with leads (PM, ICD, CRT) exhibited bacterial colonisation. Out of the 5 CDIs identified, 4 were associated with positive sonication results. In addition, our study identifies male gender and immunosuppressive medication as significant risk factors for asymptomatic bacterial CIED colonisation. Thus, in patients with these given risk factors, CIED sonication should be considered for risk stratification with regard to a subsequent CIED infection and possible targeted antimicrobial therapy.Flow Chart