This patient has signs and symptoms concerning for possible infection of an implanted cardiac electronic device. He should undergo laboratory evaluation including assessment of a complete blood count with differential, two peripheral blood cultures from separate phlebotomy sites, and an erythrocyte sedimentation rate to assess for the possibility of a device-related infection.

Patients with an implanted cardiac device can develop either a localized tissue infection at the implant site (pocket infection) or a systemic infection with bacteremia (for example, endocarditis). These infections can occur after initial implantation, late after implantation, or following a device battery replacement or revision. If left untreated, implanted cardiac device infections will progress to endocarditis and sepsis and ultimately death. The fatality rate for an untreated device infection approaches 75% to 100%. Antibiotic therapy alone is insufficient. Curative therapy requires antibiotic therapy and complete hardware removal.

The most common pathogens are coagulase-negative Staphylococcus species and S. aureus. Patients may present with fever or malaise; many also have local findings suggestive of infection, such as erythema or warmth at the implant site. These patients should undergo a laboratory evaluation for signs of infection. Elevated erythrocyte sedimentation rate, leukocytosis with a left shift, and anemia are suggestive of infection. All patients with possible device-related infection (with or without fever) should have a minimum of two blood cultures drawn from separate sites. Once there is suspicion for a device infection, referral to the patient's electrophysiologist or an infectious disease specialist is mandatory.

Pacemaker pocket aspiration should never be performed, as it can seed a sterile pocket and lead to infection, especially if there is superficial cellulitis without deeper tissue involvement.

Ultrasonographic examination of a pacemaker or defibrillator pocket may be helpful in patients with suspected implanted cardiac device infections. However, pocket fluid may not always represent infection, and sterile seromas are sometimes encountered. Therefore, pocket ultrasound has limited—if any—diagnostic value.

Even though the presenting symptoms of a device-related infection may be nonspecific and difficult to distinguish from other common, benign infections, delayed diagnosis may allow more significant complications to develop. Therefore, observation in a high-risk patient would not be appropriate.