A rare complication of blood culture-negative infective endocarditis on tricuspid valve: case report.

Background: Endocarditis is an infectious disease, with an incidence of ∼15 cases per 100 000 people, affecting the tricuspid valve in 10% of cases. Infective endocarditis with negative blood cultures (BCNIE) accounts for more than 20% of cases of infective endocarditis. Perivalvular extension of the infection represents the most detrimental complications of BCNIE.

Case summary: A 25-year-old South Asian male was admitted due to fever for 15 days and new onset chest pain. The blood tests showed an increase in inflammatory indices. A chest X-ray showed enlargement of the cardiac shadow. On cardiac examination, a holosystolic murmur at the left sternal edge border was heard. The transthoracic echocardiogram showed a filamentous formation on the tricuspid valve and communication between the aorta and right atrium with left-right shunt. A transoesophageal echocardiogram (TEE) was performed to confirm the diagnosis of IE. Three sets of blood cultures were performed, with negative results, empirical therapy was managed and a decision for TEE-guided cardiac surgery was made.

Discussion: Fistula is a rare complication of IE representing the most insidious consequence of uncontrolled infection like BCNIE, a condition that has restricted the therapeutic possibilities to empirical therapy only and to early surgery. The TEE was instrumental in diagnosing right-sided infective endocarditis and allowing us to focus on the perivalvular spread of the infection in our case.