Implantable cardioverter defibrillator lead-related methicillin resistant Staphylococcus aureus endocarditis: Importance of heightened awareness

Abstract

Methicillin resistant Staphylococcus aureus (MRSA) septicemia is associated with high morbidity and mortality especially in patients with immunosuppression, diabetes, renal disease and endocarditis. There has been an increase in implantation of cardiac implantable electronic devices (CIED) with more cases of device-lead associated endocarditis been seen. A high index of suspicion is required to ensure patient outcomes are optimized. The excimer laser has been very efficient in helping to ensure successful lead extractions in patients with CIED infections. We present an unusual case report and literature review of MRSA septicemia from device-lead endocarditis and the importance of early recognition and prompt treatment.

Key Words: Endocarditis, Methicillin resistant Staphylococcus aureus, Sepsis, Pacemakers, Implantable cardioverter-defibrillator

INTRODUCTION

The implantable cardioverter-defibrillator (ICD) reduces total mortality in patients with structural heart disease[1]. Infections of these devices have increased over the last two decades[2] and are associated with an 8.4%-11.6% increased risk of mortality when compared to hospitalizations attributed to noninfectious, cardiac device-related complications[3]. We present a case and literature review of persistent methicillin resistant Staphylococcus aureus (MRSA) septicemia that was found to be secondary to a biventricular ICD infection without any signs of device pocket infection.

CASE REPORT

An 80 year-old male with coronary artery disease status post coronary artery bypass graft surgery and implantation of a biventricular ICD 15 years ago presented with a 2-d history of fever and abdominal pain. Physical examination revealed fever, tachycardia and hypotension. Initial blood work revealed acute renal failure and MRSA bacteremia. His chest X-ray (CXR) is seen in Figure 1. Despite 2 wk of appropriate antibiotics, his blood cultures remained positive.

Figure 1 Chest X-ray before the implantable cardioverter-defibrillator lead extraction.

The patient’s central lines were removed. Comprehensive radiologic evaluations were unremarkable. The skin overlying his implantable device was normal. Further workup with a transesophageal echocardiogram (TEE) revealed 1.5 cm vegetation in his right atrium contiguous with his device leads as seen in Figure 2. He was subsequently referred for device extraction.

Figure 2 Transesophageal echocardiogram showing 1. 5 cm vegetation in the right atrium.

Under general anesthesia, an incision was made over the ICD generator. The ICD was encased in a capsule of fibrous tissue. A capsulotomy was performed and all four indwelling leads were completely removed with the use of a 16Fr excimer laser sheath (Spectranetics, Colorado Springs, CO). Microbiologic specimens taken at the time of the procedure grew MRSA. He was continued on intravenous Vancomycin with eventual clearance of his blood cultures. He underwent reimplantation of a new biventricular ICD and was discharged in stable condition.

DISCUSSION

Device-related infections are increasing and can often present with nonspecific signs and symptoms. Often these infections are secondary to skin-related flora. In fact, S. aureus bacteremia can be the sole manifestation of device infection in many individuals[4]. A high index of suspicion is necessary in patients with an ICD who present with septicemia and no evidence of pocket infection. Echocardiography is usually utilized to help in the diagnosis and treatment of cardiac implantable electronic device infections (CIED). Eight percents of vegetations on pacemaker leads can be seen by transthoracic echocardiography (TTE) as compared to 80% via TEE hence TEE should be used early in cases with a high suspicion for CIED[5]. In our case, TEE should have been used early in order to help guide the diagnosis and treatment of his condition. In a recent study, 91% of their patient population had TEE performed which helped in their outcomes with a calculated TTE sensitivity of 25.5%[6]. In urgent cases like septic or cardiogenic shock accompanied by a delay in the decrease of inflammatory markers (especially if there is a high suspicion for lead-associated endocarditis), TEE should be done immediately to help in improving the patients’ treatment outcomes[7].

In a recent study by Tarakji et al[8], 41% of 412 patients had an intact-appearing pocket despite having systemic signs and symptoms of infection with an in-hospital mortality of 4.6%. The authors noted that Staphylococcus species have consistently been the most common pathogen isolated in most cases of CIED with 44% of S. aureus infections being MRSA. In the Multicenter Electrophysiologic Device Infection Cohort, they found that a remote source of infection was usually present 38% of the time in late lead-associated endocarditis (LAE) unlike 8% for early LAE (P < 0.01). The in-hospital mortality was low for the two groups, 7% for early LAE and 6% for late LAE[9]. Patients with an implantable cardiac device who present with MRSA or methicillin-sensitive Staphylococcus aureus bacteremia should be aggressively screened for device infections especially if there are no other identifiable sources. The data are less clear for gram-negative bacteremia.

Transient bacteremia could occur during brushing of the teeth, tooth extraction or dental cleaning but the risk of its resulting in persistent MRSA bacteremia is low[10]. The American Heart Association (AHA) guidelines for antimicrobial prophylaxis before dental procedures considered patients with cardiac devices as low risk and thus not requiring routine prophylaxis[11]. Rather, improved oral health and hygiene has been encouraged to reduce the incidence of transient bacteremia that could progress to lead- associated endocarditis[11]. In patients who have had previous infective endocarditis or prosthetic cardiac valves, it is recommended that they should receive antimicrobial prophylaxis before dental procedures[12].

Managing device infections

When device-related infections occur, complete extraction is necessary to eradicate the infection. Cardiac implantable electronic device extraction is usually performed in tertiary referral centers because of the availability of expertise and the need for cardiac surgery back-up[13]. There are several methods used in lead extraction that includes traction/countertraction, grasping devices, and excimer laser sheaths aimed to debulk connective tissue surrounding leads. The ultraviolet excimer laser is particularly effective in facilitating extraction with minimal risk of perforating the vein or heart especially with chronic indwelling leads that have significant amounts of fibrous tissue surrounding them[14]. Our patient was able to undergo lead extraction without complications using the excimer laser. His follow up TTE and CXR were unremarkable.

Complications related to lead extractions and timing of reimplantation

Complications related to lead extractions have been studied in two large clinical trials. The Plexes Trial prospectively randomized 301 subjects with 465 chronic pacemaker leads and found a 94% procedural success rate in the laser group with 1.96% associated major complication[15]. In the Lexicon study, the all-cause in-hospital mortality for laser-assisted lead extraction was 1.86%: 4.3% when associated with endocarditis, 7.9% when associated with endocarditis and diabetes, and 12.4% when associated with endocarditis and creatinine ≥ 2[16]. According to the Heart Rhythm consensus statement, major complications include death, cardiac and vascular avulsion or tear, pulmonary embolism, respiratory arrest, stroke and pacing system related infection of non-infected site[13]. Some of the risk factors for complications include female gender, long implantation time, and lack of experience of the operator and ICD lead type[14].

Finally, it is important to ensure that blood cultures are negative before implanting another ICD device. Current AHA guidelines recommend a period of 72 h of negative blood cultures before implantation of a new CIED in patients with previously positive lead vegetation on TEE and blood cultures[17].