Right-Sided Endocarditis involving Eustachian Valve Following the Use of a Central Venous Line.

BACKGROUND Right-sided endocarditis is a well-known condition that occurs predominantly in intravenous drug users and patients with cardiovascular implantable electronic devices, central venous lines, and congenital heart disease. Most cases involve the tricuspid valve apparatus. Eustachian valve endocarditis (EVE) is a very rare and underdiagnosed condition with only a few previously reported cases. CASE REPORT We present a rare case of 2-sided infective thromboembolism from Staphylococcus aureus endocarditis involving both the eustachian and mitral valves in a 27-year-old man with mitochondrial neurogastrointestinal encephalopathy disease, which is a rare mitochondrial disease. CONCLUSIONS Endocarditis involving the eustachian valve is rare and presents a significant dilemma in diagnosis and treatment. Late diagnosis can lead to missed thromboembolic events and can have a significant impact on treatment and prognosis. In cases with high suspicion, early use of transesophageal echocardiography and chest CT can greatly advance diagnosis. The international guidelines do not specifically address patients with EVE; therefore, we recommend that the endocarditis team should be involved in any case of EVE to customize a treatment strategy.