Rising infection rate in cardiac electronic device implantation; the role of the AIGISRx® antibacterial envelope in prophylaxis

Emerging Bioelectronic Strategies for Cardiovascular Tissue Engineering and Implantation

Heart diseases are currently the leading cause of death worldwide. The ability to create cardiovascular tissue has numerous applications in understanding tissue development, disease progression, pharmacological testing, bio-actuators, and transplantation; yet current cardiovascular tissue engineering (CTE) methods are limited. However, there have been emerging developments in the bioelectronics field, with the creation of biomimetic devices that can intimately interact with cardiac cells, provide monitoring capabilities, and regulate tissue formation. Combining bioelectronics with cardiac tissue engineering can overcome current limitations and produce physiologically relevant tissue that can be used in various areas of cardiovascular research and medicine. This review highlights the recent advances in cardiovascular-based bioelectronics. First, cardiac tissue engineering and the potential of bioelectronic therapies for cardiovascular diseases are discussed. Second, advantageous bioelectronic materials for CTE and implantation and their properties are reviewed. Third, several representative cardiovascular tissue-bioelectronic interface models and the beneficial functions that bioelectronics can demonstrate in in vitro and in vivo applications are explored. Finally, the prospects and remaining challenges for clinical application are discussed.

Anti-biofilm activity of antibiotic-loaded Hylomate®

Introduction

Antibiotic envelopes are being developed for cardiac implantable electronic device (CIED) wrapping to reduce the risk of infections.

Methods

Fifteen CIED infection-associated bacterial isolates of Staphylococcus aureus, Staphylococcus epidermidis and Cutibacterium acnes were used to assess in vitro biofilm formation on Hylomate® compared to titanium, silicone and polyurethane coupons pre-treated with vancomycin (400 µg/ml), bacitracin (1000 U/ml) or a combination of rifampin (80 µg/ml) plus minocycline (50 µg/ml). Scanning electron microscopy (SEM) was performed to visualize bacteria on Hylomate®.

Results

There was significantly less (p < 0.05) S. aureus and S. epidermidis on Hylomate® pre-treated with vancomycin, bacitracin or rifampin plus minocycline after 24 h of incubation (≤1.00 log₁₀ CFU/cm²) compared with titanium, silicone or polyurethane pre-treated with vancomycin, bacitracin or rifampin plus minocycline. C. acnes biofilms were not detected (≤1.00 log₁₀ CFU/cm²) on pre-treated Hylomate® coupons.

Conclusions

This study showed that Hylomate® coupons pre-treated with antibiotics reduced staphylococcal and C. acnes biofilm formation in vitro.

Retrospective comparative analysis of cardiovascular implantable electronic device infections with and without the use of antibacterial envelopes

BACKGROUND

Cardiovascular implantable electronic device (CIED) infections are associated with morbidity and mortality. Peri-operative systemic intravenous antibiotic prophylaxis reduces the rate of CIED infections. AIGIS_Rx, a polymer envelope implanted with the CIED, releases minocycline and rifampin, and has been introduced to reduce infections.

METHODS

Retrospective review of 184 patients who underwent CIED implantation was conducted. Ninety-two patients were implanted with an AIGIS_Rx envelope (AIGIS_Rx group) and 92 patients were not implanted with an AIGIS_Rx envelope (control group). Data were collected on demographics and risk factors for CIED infections (i.e. congestive heart failure, renal insufficiency, chronic kidney disease, oral anticoagulant use, chronic steroid use, need for lead replacement or revision, temporary pacing, early re-intervention, and having more than two leads in place). Rates of implantation success, major infections and mortality were compared between the AIGIS_Rx group and the control group.

RESULTS

The AIGIS_Rx group had longer hospitalizations (6.8±10.7 days vs 3.1±5.2 days; P=0.001), higher chronic corticosteroid use, higher rates of replacement or revision (51.1% vs 8.7%; P=0.001), and a greater proportion of devices with more than two intracardiac leads (42.4% vs 29.3%; P=0.03) than the control group. Successful implantation occurred in 97% of patients in both groups. Major infection was seen in 5.4% of cases in the AIGIS_Rx group and 1.1% of cases in the control group (P=0.048). Device removal was conducted in 3.3% of cases in the AIGIS_Rx group compared with 1.1% of cases in the control group (P=0.16). There were two deaths in the AIGIS_Rx group. Organisms cultured were meticillin-resistant Staphylococcus aureus, meticillin-susceptible S. aureus and Enterococcus faecalis.

CONCLUSION

The AIGIS_Rx group had higher rates of major infection but also higher risk factors compared with the control group. The rate of device extraction and CIED-related mortality was higher in the AIGIS_Rx group than in the control group.

Use of an antibacterial envelope is associated with reduced cardiac implantable electronic device infections in high-risk patients

INTRODUCTION

The incidence of cardiac implantable electronic device (CIED) infections has risen rapidly since 2004. A commercially available minocycline and rifampin impregnated antibacterial envelope has been associated with a low CIED infection rate. We performed a retrospective cohort study analyzing CIED infection rates in patients receiving an antibacterial envelope.

METHODS

Prospectively applied criteria for use of the antibacterial envelope included ≥2 of the following: diabetes, renal insufficiency, anticoagulation, chronic corticosteroid use, fever or leukocytosis at the time of implantation, prior CIED infection, ≥3 leads (cardiac resynchronization therapy or abandoned leads), pacemaker dependence, or early pocket reentry. CIED infection rate was compared to a cohort of patients with matched risk factors and a CIED implanted prior to use of the antibacterial envelope.

RESULTS

A total of 260 antibacterial envelopes were implanted from November 1, 2009 to April 30, 2012. The mean number of CIED infection risk factors was 2.8 ± 1.2. The control cohort (N = 639) was matched for mean number of CIED infection risk factors (2.8 ± 1.2), though individual risk factors differed. After a minimum of 90 days of follow-up, there was one CIED infection among patients who received an antibacterial envelope (0.4%), compared to 19 (3%) in controls (odds ratio [95% confidence interval] 0.13 [0.02-0.95], P = 0.04). This difference persisted after adjustment for covariates (0.09 [0.01-0.73], P = 0.02) and propensity score matching (0.11 [0.01-0.85], P = 0.04).

CONCLUSIONS

In patients prospectively identified at high risk for CIED infection, use of a commercially available antibacterial envelope was associated with a marked reduction in CIED infections when compared to a matched control cohort.