Results
A total of 155 patients underwent a Micra TPS implant procedure from
July 2015 to July 2019 of which 15 patients (9.7%) developed a
bacteraemia during follow-up. Bacteraemia occurred at a median of 226
days (range: 3-1129) after the implant procedure. Median duration of
follow-up after the bacteraemia was 263 days (range: 15-1134). The
baseline characteristics of the population is summarized in Table 1.
Patients with bacteraemia had a median age of 81-years (77-82) and were
largely similar to the other patients with two exceptions. First, they
had a more frequent history of valve intervention (66.7% vs.27.9%,
p=0.002) and secondly, there was a higher incidence of severe renal
dysfunction requiring haemodialysis (20% vs. 3.6%, p= 0.006).
Gram positive species accounted for 73.3 % (n=11) of the bacteraemia
including Staphylococcus (n=5), Enterococcus (n=3) andStreptococcus (n=3) (Table 2). The source of infection was
identified in 9 patients (60%) including endocarditis in 4 patients,
the urinary tract in 3 patients, and the skin in 2 patients. All
patients underwent at least one transoesophageal echocardiography that
did not reveal the presence of vegetation on the Micra. Thirteen
patients were successfully treated with intravenous antibiotics. Two
patients with endocarditis underwent valvular replacement with
preventive removal of the Micra in the absence of definite signs of
device infection including negative transoesophageal echocardiography.
In both, the culture of the explanted device remained negative. All
treatments led to negative conversion of the blood cultures and no
patient experienced any recurrent bacteraemia during follow-up. Four
patients died during follow-up of which 3 patients with endocarditis.
Both patients who had removal of the Micra with valve replacement for
endocarditis died of multi-organ failure respectively 14 and 43 days
after surgery. A third patient also died of multi-organ failure 20 days
after valve surgery for endocarditis. The fourth patient died at home
from causes unrelated to the bacteraemia.
18FDG PET/CT imaging was performed in 6 patients to
identify the site of infection. No patient had abnormal18F-FDG uptake detected around the Micra on the PET/CT
fusion images (Figure 1). Two patients with endocarditis had increased18F-FDG uptake on infected valves confirmed by
positive post-operative valve culture. Two other patients had increased
focal 18-FDG uptake compatible with infectious arthritis (Table 2).