Predictors of mortality in patients with cardiovascular implantable electronic device infections

Infection reduces survival in cardiovascular implantable electronic device (CIED) recipients. However, the clinical predictors of short- and long-term mortality in patients with CIED infection are not well understood. We retrospectively reviewed all patients with CIED infection who were admitted to Mayo Clinic from January 1991 to December 2008. Survival data were obtained from the medical records and the United Sates Social Security Index. The purported risk factors for short-term (30-day) and long-term (>30-day) mortality were analyzed using univariate and multivariate models. Overall, 415 cases of CIED infection were identified during the study period. The mean follow-up duration for the 243 patients who were alive at the last follow-up visit was 6.9 years. In a multivariate model, heart failure (odds ratio 9.31, 95% confidence interval 2.08 to 41.67), corticosteroid therapy (odds ratio 4.04, 95% confidence interval 1.40 to 11.60), and presentation with CIED-related infective endocarditis (odds ratio 5.60, 95% confidence interval 2.25 to 13.92) were associated with increased short-term mortality. The factors associated with long-term mortality in the multivariate model included patient age (hazard ratio 1.20, 95% confidence interval 1.06 to 1.36), heart failure (hazard ratio 2.01, 95% confidence interval 1.42 to 2.86), metastatic malignancy (hazard ratio 5.99, 95% confidence interval 1.67 to 21.53), corticosteroid therapy (hazard ratio 1.97, 95% confidence interval 1.22 to 3.18), renal failure (hazard ratio 1.94, 95% confidence interval 1.37 to 2.74), and CIED-related infective endocarditis (hazard ratio 1.68, 95% confidence interval 1.17 to 2.41). In conclusion, these data suggest that the development of CIED-related infective endocarditis and the presence of co-morbid conditions are associated with increased short- and long-term mortality in patients with CIED infection.

Sonication of explanted cardiac implants improves microbial detection in cardiac device infections

The sonication technique has been shown to be a promising tool for microbiological diagnosis of device-related infections. We evaluated the usefulness of the sonication method for pathogen detection in 80 explanted cardiac components collected from 40 patients, and the results were compared with those of conventional cultures. Forty subjects undergoing cardiac device removal were studied: 20 had cardiac device infection, and 20 subjects underwent elective generator replacement or revision in the absence of infection. Sonication of explanted devices was more sensitive than traditional culture for microbial detection (67% and 50%, respectively; P = 0.0005). The bacterial count detected in sonication fluid culture was significantly higher than that detected in traditional culture in both infected (P = 0.019) and uninfected (P = 0.029) devices. In the infected patients, sonication fluid culture yielded a significantly higher rate of pathogen detection in explanted electrodes than traditional culture (65% versus 45%; P = 0.02), while no differences were found in the generators. Ten strains were detected only through sonication fluid culture: 6 Staphylococcus epidermidis strains, 1 Staphylococcus hominis strain, 2 Corynebacterium striatum strains, and 1 Brevundimonas sp. Neither the type nor the duration of antimicrobial therapy before device removal had an effect on the diagnostic performance of sonication fluid culture (P = 0.75 and P = 0.56, respectively). In the patients without infection, sonication fluid culture was positive in 8 cases (40%), whereas conventional culture was positive in only 4 (20%). In summary, the sonication technique improves the microbiological diagnosis of explanted cardiac devices.

Clinical features and outcomes of cardiovascular implantable electronic device infections due to staphylococcal species

Staphylococci account for the bulk of cardiovascular implantable electronic device (CIED) infections. However, a detailed analysis of clinical features and outcomes of CIED infections due to staphylococcal species has not been published. We retrospectively reviewed all cases of CIED infection seen at the Mayo Clinic from 1991 through 2008. Differences in device and host factors, clinical features, and patient outcomes were compared between cases of early and late Staphylococcus aureus and coagulase-negative staphylococci (CoNS) CIED infections. Of 280 cases of staphylococcal CIED infections, 43.9% were due to S. aureus and 56.0% were due to CoNS. Staphylococcus aureus CIED infection cases more frequently involved initially implanted devices. Late S. aureus CIED infection cases compared to late CoNS cases were associated with corticosteroid therapy, hemodialysis, implanted catheters, prosthetic valves, and remote sources of bacteremia. Cases of S. aureus endovascular infections had longer duration of bacteremia (56.0% vs 20.3% ≥3 days), longer hospitalization (37.4% vs 15.2% >20 days), and increased mortality (25.2% vs 9.5%) compared to cases of CoNS endovascular infections (p <0.001 for all comparisons). Overall, CoNS CIED infections compared to S. aureus were associated with a history of multiple device revisions and a higher number of total and abandoned leads at presentation (p <0.001 for all comparisons). In conclusion, CIED infections due to S. aureus and CoNS have distinct clinical features and outcomes.

Implantable electrophysiologic cardiac device infections: a risk factor analysis

The risk of cardiac device infection (CDI) is rising significantly, with several risk factors identified. The purpose of this study is to determine the rate of CDI at our center and to assess the associated risk factors, in order to define appropriate measures to prevent this complication. We retrospectively reviewed all cases of patients with CDI at St. George Hospital between February 1999 and July 2010. Each case was matched with three controls. We performed a descriptive and bivariate analysis to identify significant risk factors. Eighteen case patients and 54 control subjects met the inclusion criteria. An organism was recovered in 58 % of the cases. Significant risk factors included previous history of CDI (p < 0.001), recent manipulation (p < 0.001), trauma to the site of implant (p = 0.003), having a dual chamber/dual lead pacemaker (p = 0.002), and development of post-procedural hematoma (p = 0.012). Our findings complement the results of previous studies. We recommend a pre-procedural risk assessment and a thorough post-implantation follow-up to prevent the development of infective complications.

Device-related infective endocarditis, with special consideration of implanted intravascular and cardiac devices in a predominantly male population

BACKGROUND

The relationship between invasive medical devices and infective endocarditis (IE) has not been comprehensively assessed. We describe our experience of patients with IE, with particular attention to the role of pre-existing intravascular catheters and implanted cardiac devices in the pathogenesis.

METHODS

We performed a retrospective review of hospital records over a 10-y period (1997-2007), and included patients with 'definite' or 'possible' IE as per the modified Duke criteria. The complete electronic medical record was reviewed for the presence of intravascular devices prior to the onset of IE, including intravascular catheters and implanted cardiac devices (defibrillators and pacemakers).

RESULTS

We identified 155 patients with IE. Infection involved a native valve in 124 (80%) patients and a prosthetic valve in 15 (9.7%). In the remaining 16 (10.3%) patients, infection was attributed to an implanted cardiac device. The most commonly identified source of infection was a central venous catheter, accounting for 17.4% of patients, followed by an implanted cardiac device in 10.3% of patients. Staphylococcus aureus was the most commonly isolated organism in catheter-associated IE and cardiac device-associated IE (31.9% and 62.5%, respectively). Thirty-five (22.5%) patients died within 90 days. Mortality was 31.9% in patients with IE caused by methicillin-resistant S. aureus (MRSA).

CONCLUSIONS

Intravascular catheters and cardiac implantable devices are common sources of infection leading to IE, and the intracardiac devices themselves often become infected, with MRSA as the predominant pathogen.

Timing of the most recent device procedure influences the clinical outcome of lead-associated endocarditis results of the MEDIC (Multicenter Electrophysiologic Device Infection Cohort)

OBJECTIVES

The purpose of this study was to determine whether the timing of the most recent cardiac implantable electronic device (CIED) procedure, either a permanent pacemaker or implantable cardioverter-defibrillator, influences the clinical presentation and outcome of lead-associated endocarditis (LAE).

BACKGROUND

The CIED infection rate has increased at a time of increased device use. LAE is associated with significant morbidity and mortality.

METHODS

The clinical presentation and course of LAE were evaluated by the MEDIC (Multicenter Electrophysiologic Device Cohort) registry, an international registry enrolling patients with CIED infection. Consecutive LAE patients enrolled in the Multicenter Electrophysiologic Device Cohort registry between January 2009 and May 2011 were analyzed. The clinical features and outcomes of 2 groups were compared based on the time from the most recent CIED procedure (early, <6 months; late, >6 months).

RESULTS

The Multicenter Electrophysiologic Device Cohort registry entered 145 patients with LAE (early = 43, late = 102). Early LAE patients presented with signs and symptoms of local pocket infection, whereas a remote source of bacteremia was present in 38% of patients with late LAE but only 8% of early LAE (p < 0.01). Staphylococcal species were the most frequent pathogens in both early and late LAE. Treatment consisted of removal of all hardware and intravenous administration of antibiotics. In-hospital mortality was low (early = 7%, late = 6%).

CONCLUSIONS

The clinical presentation of LAE is influenced by the time from the most recent CIED procedure. Although clinical manifestations of pocket infection are present in the majority of patients with early LAE, late LAE should be considered in any CIED patient who presents with fever, bloodstream infection, or signs of sepsis, even if the device pocket appears uninfected. Prompt recognition and management may improve outcomes.

Cardiac device-related endocarditis complicated by spinal abscess

BACKGROUND

Infective endocarditis is the most serious manifestation of cardiac device infection and metastatic seeding of distant sites has been reported. However, the association between device-related endocarditis and spinal abscess has not been fully described.

METHODS

We reviewed hospital records at three high-volume cardiovascular referral centers from January 2005 to October 2010. Device-related endocarditis was confirmed in all cases with positive blood cultures and transesophageal echocardiogram revealing lead and/or valvular vegetations. Six patients with spinal abscesses in association with device-related endocarditis were identified.

RESULTS

A total of 384 patients met the clinical criteria for device-related endocarditis. Among these, infection was complicated by spinal abscess formation in six (1.5%) cases. The mean age of patients was 69.3 ± 11.8 years (47-82 years). The predominant clinical manifestations in these six patients included a recent history of fever (six), malaise (four), and neurological or meningeal signs (five). Spinal abscesses were diagnosed by magnetic resonance imaging in two and computed tomography scans in four of the cases. The causative pathogens were methicillin-resistant Staphylococcus aureus (three), methicillin-sensitive S. aureus (one), coagulase-negative Staphylococci (two), and Enterococcus fecalis (one). All patients underwent complete device removal with no procedure-related complications. Two patients died in the hospital, two were discharged with permanent neurological deficits, and the remaining two recovered with no permanent neurologic sequelae.

CONCLUSION

Device-related endocarditis must be considered in patients who present with a spinal abscess and bacteremia. Early recognition of this scenario is imperative in order to avoid permanent neurological sequelae and patient mortality. Early imaging, appropriate parenteral antimicrobial therapy, and expedited removal of all cardiac hardware are pivotal for optimal management.