B35-35 Breaking Resistance: Imaging-guided Remission With Rituximab in Cardiac Sarcoidosis

Introduction Cardiac sarcoidosis (CS) is an inflammatory cardiomyopathy that can progress to arrhythmias, heart failure, or sudden death. Some patients develop multidrug-resistant CS (MDR-CS), risking fibrosis despite standard therapy. We report two biopsy- or imaging-confirmed MDR-CS cases that showed clinical and imaging improvement with rituximab, supporting its potential role in B-cell-mediated disease. Description Patient A was a middle-aged woman with biopsy-proven cardiac sarcoidosis and recurrent myocardial inflammation despite corticosteroids, leflunomide, and infliximab. Serial ^18FFDG PET scans revealed worsening myocardial uptake (20% to 36% segmental involvement) and the emergence of scarring (0% to 18%), paralleled by a decline in LVEF (47% to 40%). Rituximab was initiated (1000 mg at baseline, 2 weeks, and 6 months). Follow-up PET scans at 16 and 22 months post-rituximab showed complete resolution of inflammation and scarring. LVEF improved to 45%, and symptoms stabilized. Patient B had multisystem sarcoidosis with overlapping autoimmune neurologic disease and chronic cardiac involvement. Following an infectious episode, she developed reduced LVEF (∼45%). Rituximab infusions every six months, combined with biweekly IVIg, led to restoration of LVEF (∼60%), resolution of neurologic symptoms, and normalization of PET myocardial activity. Both patients tolerated rituximab without serious adverse effects; one received prophylactic antibiotics. Discussion These cases highlight rituximab’s potential as a steroid-sparing, disease-modifying therapy in multidrug-resistant cardiac sarcoidosis (MDR-CS), achieving PET-confirmed inflammation remission and LVEF stabilization or improvement. Both patients had failed prior immunosuppression, suggesting a key role for B-cell-driven inflammation in select phenotypes. Rituximab was well tolerated without infusion reactions or severe infections. Symptom-driven imaging and adherence review were essential for timely escalation. One patient also received IVIg, reflecting the need to tailor treatment in those with immune dysregulation. These findings reinforce interest in B-cell-targeted therapy for MDR-CS and support the need for prospective trials.