Abstract Body (Do not enter title and authors here): Background: ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) is valuable for the diagnosis of cardiac sarcoidosis (CS). Although current guidelines recommend maintaining the initial maximum dose of prednisolone (PSL) for one month after its initiation, the prognostic significance of FDG-PET performed at one month following the initiation of PSL remains unclear. We sought to investigate whether FDG-PET performed at one month after the initiation of PSL was associated with adverse events in patients with CS.
Methods: We examined 110 consecutive CS patients performed FDG-PET at diagnosis and one month following the initiation of PSL between January 2010 and January 2025 in a university hospital. All patients were initiated on an initial dose of PSL at 30 mg/day or 1 mg/kg/day, or an equivalent dose. We calculated the change in the maximum standardized uptake value (SUVmax) on FDG-PET from diagnosis to one month after the initiation of PSL. A responder to the maximum dose of prednisolone was defined as a decrease in SUVmax of at least 25%, while a non-responder was defined as a decrease of less than 25% or any increase, in line with previous reports. Patients were classified as either responders (n = 84) or non-responders (n = 26). The primary outcome was a composite of sustained ventricular tachycardia/fibrillation (VT/VF), worsening heart failure (HF), and all-cause death.
Results: The median age was 63 ± 11 years, and 87 patients (79.1%) were female. The median left ventricular ejection fraction (LVEF) was 45 (IQR 37–60) %. Patients with non-responder had higher cardiac troponin T levels and lower estimated glomerular filtration rate compared to those with responder. There were no significant differences in age, past history, LVEF, brain natriuretic peptide levels between the groups. During a median follow-up period of 3.3 (IQR 1.1–6.2) years, the primary outcome occurred in 34 patients (30.9%). Patients with non-responder showed significantly higher incidence of primary outcome (P = 0.006) (Figure). In multivariable Cox analyses, non-responder status was significantly associated with the primary outcome, sequentially adjusted for history of VT/VF (HR 2.32, P = 0.022) and then for LVEF (HR 2.15, P = 0.036).
Conclusions: FDG-PET performed one month after initiating PSL was associated with adverse events in patients with CS, suggesting its utility in risk stratification and therapeutic decision-making prior to starting PSL tapering.