Cardiac Inflammatory Pseudotumor Following Atrial Septal Defect Repair: A Rare Complication Managed with Sirolimus and Bevacizumab

Introduction: Inflammatory pseudotumors (IPTs) of the heart are rare, non-neoplastic lesions that can mimic heart neoplasms and are exceptionally uncommon following congenital heart surgery. We report a unique case of a cardiac IPT presenting decades after atrial septal defect (ASD) repair, managed with surgical debulking and targeted therapy. Case Presentation: A 35-year-old woman with a history of ASD repair at age 6 presented in March 2023 with progressive exertional dyspnea over 5 months. Imaging revealed a 4.2 × 3.8 cm mass involving the interatrial septum (IAS), right atrium (RA), and superior vena cava (SVC). Debulking surgery in August 2023 confirmed an IPT histopathologically. Due to residual disease, she received sirolimus and bevacizumab, resulting in a reduction of the residual mass (2.1 × 1.8 cm) and complete resolution of symptoms by August 2024. Conclusions: This case demonstrates the first successful use of sirolimus-bevacizumab combination therapy for a cardiac IPT following ASD repair. This strategy offers a viable alternative for unresectable lesions and underscores the need for long-term surveillance in patients with prior cardiac surgery to detect rare inflammatory complications.