Prevalence of bloodstream infection with different microorganisms in patients with leadless pacemakers - a Danish nationwide cohort study

Background There is a lack of real-life data on the risk of bloodstream infection (BSI) with different microorganisms and subsequent outcomes in patients with a leadless pacemaker. Purpose To estimate the prevalence of microorganism-specific BSI in patients with a leadless pacemaker. Secondly, to estimate 30 and 180-day rates of infective endocarditis (IE) hospitalisation and all-cause mortality after BSI. Methods We identified patients with a leadless pacemaker (2015-2023) from the Danish Pacemaker and ICD Register. Patients were included at date of leadless pacemaker implantation, irrespective of possible prior non-leadless CIEDs. The primary endpoint of BSI was identified from the Danish Microbiology Database and defined as one or more positive blood cultures after leadless pacemaker implantation. Microorganisms were identified at species level if available, alternatively at genus or group level. In patients with BSI, secondary outcomes of IE hospitalisation and all-cause mortality within 30 and 180 days from BSI were identified. IE hospitalisations were identified via diagnosis codes in the Danish National Patient Register, mortality from the Danish Civil Registration System. Results We included 980 patients with a leadless pacemaker, 71.4% males, median age 79 years [IQR: 73, 83]. Prior non-leadless CIED implantation was seen in 310 (31.6%) patients. A diagnosis with BSI or IE prior to inclusion was observed in 179 (18.3%) and 215 (21.9%) patients, respectively. At inclusion, 402 (41%) patients had ischaemic heart disease, 263 (26.8%) heart failure, 179 (18.3%) cancer, 228 (23.3%) diabetes, 84 (8.6%) on haemodialysis, 414 (42.2%) had undergone surgery within the last year. In the study period, BSI was observed in 163 (16.6%) patients, 13 (8%) with polymicrobial BSI. We identified more than 50 species. The most frequent microorganisms were Escherichia coli (E.coli), Coagulase-Negative Staphylococci (CoNS) and Staphylococcus aureus (S.aureus) (Fig. 1). A diagnosis of IE hospitalisation was registered in 21 (12.9%) patients both within 30 and 180 days of BSI. All-cause mortality within 30 days of BSI occurred in 60 (36.8%) patients, while 86 (52.8%) died within 180 days (Fig. 2). S.aureus n=8 (29%) and Enterococcus faecalis n=6 (21%) were the predominant species in patients with IE hospitalisation within 180 days from BSI. The most frequent species in patients who died within 180 days from BSI were E.coli n=23 (21%), S.aureus n=18 (16%) and Klebsiella pneumoniae n=9 (8%). Conclusion BSI was observed in every sixth patient with a leadless pacemaker, caused primarily by E.coli, CoNS and S.aureus. IE hospitalisation and all-cause mortality within 180 days from BSI was observed in 12.9% and 52.8% of patients, respectively. Our results highlight the vulnerability of this patient population and warrant further investigation on the risk of infection and subsequent outcomes in patients with leadless pacemakers.Prevalence of microorganismsFig. 2.Endpoints: BSI, IE, mortality