The main result of our study is that local symptoms at the site of pacemaker implantation are highly correlated (79.3%) with a positive culture of the intravascular part of the leads. This strong and striking correlation is present whatever the nature of these symptoms, and even in cases where the symptoms were an isolated finding after an extensive work up for infective endocarditis. Lead removal is associated with a favourable outcome; the converse was true when this removal was not achieved.
Our results confirm the mechanism of intravascular infection originating from the pacemaker pocket with subsequent risk of progressing to systemic infection or right heart endocarditis. Da Costa and colleagues have shown that pacing system infections are mainly caused by local contamination by local bacteriological flora during implantation.1
Skin microorganisms migrate from the insertion site along the surface of the lead, colonising its distal intravascular part and ultimately infecting the blood stream. Studies by transmission and scanning electron microscopy have shown that nearly all indwelling vascular catheters are colonised by microorganisms.5
There is agreement that all the implantable material should be extracted in patients with septicaemia related to an infected pacing system.6–21
On the other hand, there is no clear consensus with respect to the management of pathological findings limited to the pacemaker implantation site, though the trend is toward extraction of the entire system when the cause is infectious, rather than conservative management for purely mechanical complications.22
Patients with class I indications for lead removal according to the NASPE policy23
were excluded from our study, as clearly stated in the Methods section. Our study dealt with class II indications in order to confirm or invalidate the policy of hardware removal. The study highlights the difficulty of excluding the presence of an infection on the grounds of clinical observation or detailed investigations. Griffith and colleagues have proposed a two step approach primarily based on the results of wound swab cultures, reporting the need for a new contralateral pacemaker in fewer than 40% of patients after a mean follow up of 21.3 months.22
However, the lack of reliability of their wound swab cultures was illustrated by negative results in nearly 30% of patients who ultimately developed recurrences.22
In our study, 38.1% of wound swab cultures were positive, contrasting with 91.6% of positive lead cultures; one may question the appropriateness of exposing patients to an approach based on a test with such a low sensitivity.
In this series, some patients without complete lead removal had recurrences with systemic infection not present at the time of recruitment. As failure rates of percutaneous lead extraction procedures increase with the age of the lead,2,3
postponement of the procedure may not only allow the growth of large vegetations, with a risk of massive pulmonary embolism at the time of extraction, but also renders extraction more difficult. On the other hand, lead extraction procedures are technically challenging and carry a risk of death. In this study, though procedural mortality was 1.9%, this risk has to be compared with the risk of death in cases of uncontrolled infection—infection recurred in half the patients without complete extraction of the lead body, and this recurrence was fatal in one of these patients (12.5%).
Our studies were not designed to provide recommendations about antibiotic treatment. However, staphylococci adherent to polymer surfaces and their capacity for biofilm formation contribute to the pathogenesis of infections with implanted medical devices.24
The sterilisation of infected implanted devices by antibiotics is extremely difficult. This is why prolonged use of intravenous antibiotics is not the recommended form of treatment for infected pacemakers if the implanted material has not been removed.15,23
The very small proportion of patients with antibiotic treatment before referral in this series could explain the 38.1% of positive wound swab cultures in our series in comparison with the 22.5% in the series by Griffith and colleagues (p
0.04). However, antibiotic treatment before lead extraction would probably not modify the results of cultures obtained directly from the implanted material, especially lead cultures. Several investigators have proposed conservative treatment,25–29
and conservative management is required if lead extraction is impossible, unsuccessful, judged too risky, or refused. In cases where infected leads remain in place, prolonged follow up is required and perhaps prolonged antibiotic treatment.
Almost all patients were referred from secondary care centres, and then admitted to our tertiary centre, specialising in pacemaker lead extractions. It should be emphasised that 28 patients (table 1, history of local complication) had undergone several previous therapeutic attempts because of their local symptoms before referral and inclusion in this study. This may have introduced a referral bias, with a selection of a larger proportion of infectious complications resistant to the previous conservative management usually undertaken in the referral centres. This bias, however, seems to have had a limited impact because the nature of the last procedure preceding inclusion in the study, and the percentage of patients with previous conservative surgery for local complications, were not statistically different in those with and without positive lead cultures.
Regardless of the initial clinical presentation, complications at the pacemaker implantation site are associated with an infectious process in the vast majority of cases. Furthermore, even in the absence of signs or symptoms of systemic infection, the process is rarely limited to the extravascular components of the pacing system. Consequently, the management of local symptoms—even when apparently confined to the pulse generator implantation site—should prompt the extraction of the entire system. A recurrence rate of infection in 50% of patients in whom the leads were not fully removed strongly supports this recommendation.