This chapter focuses on the recognition, diagnosis, and management of cardiac implantable electronic device (CIED) infections and infective endocarditis, as well as conditions associated with significant morbidity and mortality, particularly in hospitalized patients. It outlines the clinical presentations ranging from localized pocket infections to systemic bacteremia and device-related endocarditis, emphasizing the importance of high clinical suspicion in patients with fever, positive blood cultures, and CIEDs. This chapter guides hospitalists through diagnostic pathways, including the use of transesophageal echocardiography (TEE), blood culture timing, and key laboratory findings. It distinguishes between simple device-site infections and invasive CIED endocarditis, which necessitates complete device removal and prolonged antibiotic therapy. For infective endocarditis, the modified Duke criteria are reviewed alongside common causative organisms (e.g., Staphylococcus aureus, streptococci, and enterococci), and the implications of prosthetic valves or prior endocarditis. Management principles cover empiric and pathogen-directed antibiotic selection, surgical indications, and coordination with infectious disease and cardiology teams. Special considerations are given to patients with prosthetic valves, immunosuppression, or recent healthcare exposures. This chapter equips hospitalists with the tools to initiate timely diagnosis, reduce complications, and facilitate multidisciplinary care in these high-risk cardiac infections.