The significance of investigation into underlying coronary artery fistula in patients with tricuspid valve endocarditis: a case report

Coronary artery fistula (CAF) is an uncommon congenital heart disease (CHD). Most patients are asymptomatic, and CAFs are typically discovered incidentally on echocardiography or computed tomography coronary angiography (CTCA). Although previous reports have suggested an association between CAF and infective endocarditis, there are few reports on the coexistence of CAF and tricuspid valve infective endocarditis (TVIE). We report a rare case where a CAF was identified as the underlying CHD in TVIE using multimodal imaging. Both the CAF and TVIE were successfully treated surgically.

A Japanese woman in her 40 s who presented with a fever of 38°C that persisted for 4 days. Streptococcus oralis was isolated from two sets of blood cultures obtained on admission. Tricuspid valve vegetation was detected using transthoracic echocardiography, and a CAF, which originated from the right coronary artery (RCA) and terminated in the right atrium (RA), was detected by CTCA. Furthermore, the CAF and turbulent shunt flow directed towards the tricuspid valve were identified on transoesophageal echocardiography and subsequently confirmed as an RCA–RA fistula on coronary angiography. After antibiotic therapy, the patient underwent vegetation resection, tricuspid valve annuloplasty, and CAF excision.

Careful investigation of the underlying CHD is necessary when TVIE is found. In patients with TVIE, multimodal imaging is useful for investigating underlying CAF and the direct association between TVIE and CAF. When multimodal imaging suggests a direct association between CAF and TVIE, surgical resection of both the TVIE and CAF is essential to prevent the recurrence of TVIE.