When echocardiography fails: Fatal Staphylococcus aureus endocarditis of a right ventricle-pulmonary artery conduit in an adult with DiGeorge syndrome (Lessons from a delayed PET/CT diagnosis)

Background: 22q11.2 Deletion Syndrome (DiGeorge Syndrome) confers a high risk for infective endocarditis (IE) due to coexisting conotruncal heart defects, prosthetic material, and immune deficiency. Diagnosing IE on a right ventricle-to-pulmonary artery (RV-PA) conduit can be challenging. Case summary: A 31-year-old female with 22q11.2 deletion syndrome and repaired pulmonary atresia with a ventricular septal defect (RV-PA conduit) presented with febrile syndrome two months after pacemaker implantation. Initial transesophageal echocardiography (TEE) was negative. She was treated for a pacemaker lead infection with lead extraction and antibiotics, with initial improvement. She relapsed shortly after completion of therapy.The second TEE was not diagnostic. A definitive diagnosis was only achieved by 18F-FDG PET/CT, which demonstrated intense uptake at the conduit and a septic embolism in the fourth dorsal vertebra. Despite emergency surgery, the conduit was found to be destroyed by a fistulizing pseudoaneurysm, and the patient died due to uncontrollable hemorrhage. Conclusion: This fatal case highlights the critical limitations of echocardiography in diagnosing prosthetic conduit endocarditis. 18F-FDG PET/CT was the pivotal diagnostic modality, confirming the infection after all other methods failed. This underscores the necessity of integrating advanced molecular imaging early in the diagnostic algorithm for such high-risk patients to enable timely intervention and prevent catastrophic outcomes.