Mortality and patient stratification 30 days after Staphylococcus aureus bacteraemia in patients with cardiac implantable electronic devices - a Danish nationwide cohort study
Authors: Bengtsen K , Le M V , Haugan K , Philbert B T , Johansen J B , Torp-Pedersen C , Riahi S , Nielsen J C , Larroude C , Petersen A , Larsen A R , Ostergaard L , Fosbol E L , Bruun N E , Ruwald A C 
Published: October 2024

Abstract

Background
Staphylococcus aureus bacteraemia (SAB) is a high-risk condition with a reported 30-day mortality of up to 25% even with timely and correct treatment. Patients with cardiac implantable electronic devices (CIEDs) are at increased risk of a complicated course of disease due to the risk of device infection.

Purpose
We aimed to estimate the 30-day mortality rate following SAB among adult Danish patients with a de novo CIED. Furthermore, we aimed to identify patients with low, intermediate, and high mortality risk following SAB.

Methods
Using The National Danish Staphylococcus Aureus Bacteriemia Database and The Danish Pacemaker and ICD Register, we identified all Danish patients aged 18 to 99 years with a de novo CIED implantation between 2000 and 2020, and subsequently positive Staphylococcus aureus blood culture. The primary outcome was 30-day all-cause mortality from date of SAB. Clinical variables significantly associated with increased 30-day mortality following SAB were identified (p&lt;0.05 and 95% CI not including 1) using adjusted multivariable Cox regression modelling. We tested variables related to age, sex, calendar year of SAB, device type, timing of infection, previous SAB, concomitant medication, and clinically relevant pre-existing co-morbidities including valvular replacement, recent surgery, and renal dialysis. Patients were awarded 1 point for each of the significant variables present, and the sum was used to stratify into low-, intermediate-, and high-risk groups. The cut-offs between the groups were set at 0 and 2 points (0 points = low risk, 1-2 points = intermediate risk, ≥3 = high risk).

Results
We identified 1,393 patients with de novo CIED (pacemaker: n=983, implantable cardioverter defibrillator: n=230, cardiac resynchronization therapy w/wo defibrillator capacity: n=180) and subsequent SAB (median time to SAB from CIED implantation: 679 days [IQR 168-1,525]). Median age at the time of SAB diagnosis was 77 years [IQR 68-84] with 72.4% being males. In total, 469 patients died within the first 30 days from SAB, equivalent to an overall 30-day mortality rate of 33.7% (95% CI 31.2-36.2). We identified high age, left sided valvular disease, use of systemic corticosteroids, and SAB occurring &gt;6 months from CIED implantation to be associated with an increased hazard of 30-day mortality following the SAB diagnosis (Fig. 1). The median total sum obtained from the stratification model was 2 points [IQR 1-2]. 30-day all-cause mortality was estimated to 16.2%, 31.6% and 54.9% for the low-, intermediate- and high-risk groups, respectively (Fig. 2).

Conclusions
In patients with a de novo cardiac implantable electronic device and subsequent Staphylococcus aureus bacteraemia the overall 30-day mortality from date of SAB was 33.7%. Patients with high age, recent surgery, left sided valvular disease, and use of systemic corticosteroids were particularly at risk.Fig. 1.Simplified stratification modelFig. 2.30-day mortality following SAB