Thrombocytopenia and end stage renal disease are key predictors of survival in patients with cardiac implantable electronic device infections

Cardiac implantable electronic device (CIED) infections are associated with a high mortality. Our aim was to identify key predictors of survival in patients with CIED infections as to be able to detect high‐risk patients and possibly affect modifiable factors.

The high mortality rate associated with these infections was the stimulus for our group to investigate our center's experience. It was our goal to identify specific predictors which would allow us to detect patients at an increased risk of mortality and identify modifiable factors. It is an understanding of the individual patient's risk which will allow us to provide more accurate information preoperatively and a greater level of resources in the perioperative period.
Ultimately in the next years it must be our objective, not only to reduce the burden of CIED infections but also to improve the mortality associated with such infections.

Study design
We performed an observational study in which demographic characteristics, procedural data, and postoperative outcomes were collected from our local operative data collection system, patient files, and routine postoperative follow-up. Our cohort included all the patients treated for CIED infections in our department from 2001 to 2017. The study was approved by the local ethics committee.

Definitions and current patient management
Based on the therapeutic distinctions made in the Heart Rhythm Society 4 consensus statement on lead extraction, 3

Statistical analysis
Data analysis was performed using R Version 3.5.0 5 with the support of the additional software packages: Rcmdr, 6 survival, 7 ggplot2, 8  and in the CIEDR-IE group 39 patients (26.4%) presented with local symptoms. In the CIEDR-IE group 87 patients (58.8%) and in the IPI group 6 patients (4.7%) presented with fever (For more information on presenting symptoms see Tables S1 and S2).

Procedural goals and procedural success
In 230 cases (83.0%) the goal of the procedure was removal of the CIED and leads. In eight cases (2.9%) the patient was referred to our tertiary care center for lead removal after failed lead removal in a secondary care center. Patient characteristics or the patient's wish dictated that the generator be removed but the leads remain in place in 28 cases (10.1%) and that local wound debridement or wound revision be performed in 11 cases (4.0%). Complete procedural success 3 of lead extraction could be achieved in 207 (87.0%) and HERRMANN ET AL.

Microbiological features of infection
The bacterial species encountered in our patients can be found in Table 1. (See Table S3 for the source of bacterial isolates in the patients with bacteria discovered in intraoperative material and Table S4 for the microbiological results of polymicrobial infections).

Survival
In the complete cohort the survival rate at 30 days was 94.9%

Complications and recurrent infections
Three major complications occurred in our cohort. One patient was reanimated intraoperatively after developing sinus arrest, one patient required operative treatment of hemopericardium and one patient required operative treatment for a laceration of the brachiocephalic-caval junction. Eight patients in our cohort developed a recurrent IPI of the newly implanted pacemaker.
Three further patients developed a CIEDR-IE of the new CIED after complete removal of the initial device.
F I G U R E 1 Time since last cardiac implantable electronic device (CIED) procedure (A) and time since initial CIED implant (B) in patients with CIED infection. In both graphs the time since the last CIED procedure is featured in red with blue depicting the time from the last to the initial procedure in B T A B L E 1 Microbiological results in patients with cardiac implantable electronic device infection depending on the source of the materials cultured, ie, blood culture or culture of swabs/intraoperative material (generator pocket swab, generator pocket tissue, lead or valve tissue)
Anemia has also been associated with frailty 20,21 such that a further possible explanation is that anemia is a confounder and patient frailty is the cause for an increased mortality in the anemic subgroup.

| CONCLUSION
In this investigation of our 17-year experience with the treatment of CIED infections we were able to underline the previously known high mortality associated with this condition. We identified key predictors of 1-year mortality. We recommend a critical evaluation of patient history and preoperative laboratory parameters in patients with CIED infection. Patients with ESRD and patients with thrombocytopenia may be viewed as high-risk patients and should be treated with caution. The role of platelets in the immune response warrants further preclinical as well as clinical research as their role in immunity could have an impact of future therapeutic approaches.