Introduction: Immunosuppression (IS) is standard of care for treatment of cardiac sarcoidosis (CS) and is associated with reduction in cardiac morbidity. However, the optimal duration of therapy has not been defined, and there are only limited data describing outcomes and imaging findings after discontinuation of immunotherapy.
Methods: Patients with CS referred to a university medical center between 2009 and 2016 were retrospectively identified, and disease activity was monitored by serial 18-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET). Demographics, IS regimens, rates of disease recurrence, and cardiac events were compared in CS patients who discontinued IS versus those who continued IS. Differences in cardiac events stratified by CS recurrence were analyzed. Myocardial FDG uptake normalized to liver uptake was quantified and compared in CS patients before IS, during IS, and after IS discontinuation if applicable.
Results: Of 29 CS patients, 14 with serial PET scans were included in this study. Patients were predominantly white (79%) with few medical comorbidities at the time of CS diagnosis. During a mean 32.3 month follow-up, 6/8 (75%) CS patients who discontinued IS experienced radiologic CS recurrence compared to 2/6 (33%) patients who did not achieve CS suppression despite continuing IS (p<0.01). Among patients who experienced CS recurrence, 4/8 experienced ventricular arrhythmia within 4 months after discontinuation of therapy versus 1/6 who did not exhibit active disease by PET. Maximum normalized myocardial FDG uptake decreased by 56% while on IS, and subsequently increased by 36% after discontinuation of IS (Figure).
Conclusion: These results suggest increased risks of radiologic disease recurrence and VT associated with IS discontinuation in CS. FDG uptake quantification may provide a clinically useful method for monitoring CS treatment effectiveness and recurrence.