Silent but Significant: A Case of Indwelling Chemoport-Associated Eustachian Valve Endocarditis

Eustachian valve endocarditis (EVE) is a rare form of endovascular endocarditis, often associated with the use of indwelling venous catheters. We present a case of a 75-year-old immunocompromised female with multiple comorbidities, including a history of methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) septic joint infection, who was admitted for acute hypoxic respiratory failure secondary to a chronic obstructive pulmonary disease exacerbation. Blood cultures revealed MRSA bacteremia resistant to clindamycin, prompting initiation of intravenous vancomycin. Transthoracic echocardiography (TTE) suggested a possible mobile density in the left ventricle, though limited by body habitus. Transesophageal echocardiography (TEE) confirmed a 0.8 x 0.2 cm mobile echodensity on the eustachian valve, consistent with EVE. The source of infection was suspected to be the patient's indwelling chemoport, whose catheter tip terminated adjacent to the eustachian valve. The port was surgically removed, and cultures from the catheter tip were negative. The patient was treated with eight weeks of intravenous antibiotics, initially with daptomycin, which was discontinued due to drug-induced fever, necessitating re-initiation of vancomycin. This case underscores the importance of considering non-valvular endovascular sites, such as the eustachian valve, in patients with persistent bacteremia, particularly in the presence of intravascular devices. While EVE often presents asymptomatically and is diagnosed incidentally, TEE remains the diagnostic modality of choice due to its superior visualization of vegetations, especially in patients with suboptimal TTE imaging windows. Source control through removal of infected hardware and tailored antimicrobial therapy based on pathogen susceptibility and patient tolerability remains the cornerstone of management. This case highlights the importance of heightened clinical suspicion and a multidisciplinary approach to achieve successful outcomes in rare presentations of endocarditis.