Staphylococcus aureus bacteremia in Danish patients with cardiac implantable electronic devices: an explorative epidemiological study
Authors: Bengtsen K , Fosboel E , Haugan K , Philbert B T , Johansen J B , Torp-Pedersen C , Riahi S , Nielsen J C , Petersen A , Larsen A R , Bruun N E , Ruwald A C 
Published: October 2022

Abstract

Background
Device-related infection is the most common serious complication in patients with cardiac implantable electronic devices (CIED). Staphylococcus aureus accounts for up to 30% of CIED-related infections. There is a lack of scientific literature investigating risk of Staphylococcus aureus bacteremia (SAB) in CIED-patients.

Purpose
We aimed to describe the risk of SAB in Danish patients with a CIED through the years 2000–2018 compared to the background population.

Methods
Patients who received a CIED from 2000–2018 were identified from The Danish National Pacemaker and ICD Register. Patients were matched 1:5 on age and gender with the background population. We identified the primary endpoint of first time SAB from The National Danish Staphylococcus Aureus Bacteremia Database. The cumulative incidence of SAB was calculated using the Aalen-Johansen estimator, adding competing risk of death into account. Hazard ratios were estimated by Cox regression models adjusting for age and gender. Crude rates of relapse SAB, defined as a new SAB episode 14–180 days after first SAB, and device extractions were reported for all patients who survived 14 days from SAB diagnosis.

Results
We identified 79,324 CIED-patients (pacemaker (PM) = 61,227; Implantable Cardioverter Defibrillator (ICD) = 11,635; Cardiac resynchronization therapy, PM or ICD (CRT) = 6,364 and 396,590 matched controls (median age 75.5±13.3 years; 61% males). Age and gender distribution differed significantly by device type (age: PM 76.1±12.1; ICD 62.4±13.4; CRT 68.0±11.1; males: PM: 55.6%, ICD% 75.5: CRT: 80.9%). Across a mean follow-up of 5.9 (±4.6) years, we observed first episode of SAB in 1,430 (1.8%) CIED-patients, compared to 2,599 (0.7%) patients in the control population (p&lt;0.001).
The 10-year cumulative incidence of SAB was 1.0% for controls and 2.2% for CIED patients. The risk of SAB differed substantially by device type (Figure 1). Compared to controls and adjusted for age and gender, increasing hazard ratios for SAB were observed with more advanced devices: PM 1.12 (1.11–1.13); ICD 1.36 (1.33–1.39); CRT 1.55 (1.51–1.59). However, CIED-patients with SAB did not have higher 30-day mortality rates than the non-CIED control population with SAB (Controls 34.8%; PM 35.1%; ICD 28.1% CRT 26.1%, p=0.016). Out of all SAB patients who survived 14 days from SAB diagnosis (Controls=1,672; CIED=1,107), relapse SAB occurred in 52 (3.1%) controls and in 51 (4.6%) CIED-patients (PM 4.0%; ICD 5.8%; CRT 6.3%). Device extraction within 14 and 30 days from SAB diagnosis was undertaken in less than 30% of the CIED-patients (PM: 11.3/13.6%; ICD: 22.7/27.5%; CRT: 17.4/20.1%).

Conclusion
The occurrence of SAB was higher in CIED patients compared with controls and increased with more advanced devices. There was no difference in 30-day mortality after SAB between CIED patients and controls. Relapse SAB occurred in less than 7%, despite a low percentage of early device extractions.

Funding Acknowledgement
Type of funding sources: None.