Abstract Body (Do not enter title and authors here): Background:
Cardiac sarcoidosis (CS) was characterized by formation of granulomas in the heart. Enhancement in myocardial inflammatory activity and oxidative stress is a crucial cause of major cardiovascular adverse events (MACE). Although immunosuppressive therapy is recommended for active CS, there is no established markers for treatment and prognosis.

Hypothesis:
We hypothesized that the inflammation and oxidative stress in heart were associated with MACE after steroid therapy.

Aims:
We identified prognostic markers for MACE in patients with CS after steroid therapy.

Methods:
This study was a prospective observational cohort study. Patients with CS diagnosed according to Japanese criteria were enrolled in this study. Patients with abnormal accumulation of ¹⁸F-FDG in heart were treated with steroids with standard guideline-recommended protocol. ¹⁸F-FDG PET were performed after more than 6 months of induction. Urinary 8-hydroxy-2'-deoxyguanosine (U-8-OHdG), a marker of oxidative DNA damage, and indices of cardiac and renal function were measured. The major outcome was a composite of the first sustained ventricular tachycardia (sVT) /sudden cardiac death (SCD), hospitalization for heart failure, and radiological relapse with exacerbation of clinical manifestation.

Results:
Fifty consecutive patients with CS underwent steroid therapy and followed up (median follow-up period of 58 months). 39 of 50 patients underwent 18F-FDG PET/CT more than 6 months after steroid therapy. During the follow-up period, 17 of 39 patients showed MACE, consisting of sVT/SCD (N= 11), hospitalization (N= 2) and radiological relapse (N= 4). A Cox proportional-hazard model showed that the U-8-OHdG and SUV max value of FDG-PET were independent predictors of MACE. ROC analysis revealed that the cut-off values of U-8-OHdG and SUV max for predicting the MACE were 11.6 ng/mg Cr (AUC 0.913, sensitivity 86.7%, specificity 90.0%) and 4.64 (AUC 0.878, sensitivity 76.5%, specificity 91.0%), respectively (Fig.1). Patients with a U-8-OHdG ≧11.6 ng/mg Cr or SUV max ≧4.64 had a significantly higher MACE risk (P values for U-8-OHdG and SUV max were both 0.001 by Log Rank analysis) (Fig.2). It is noted that U-8-OHdG <11.6 ng/mg Cr and SUV max <4.64 after steroid therapy indicate the good responses to the immunosuppressive therapy and better prognosis (Fig.3).

Conclusion:
U-8-OHdG and SUV max may be useful markers in determining the therapeutic efficacy and clinical outcome in patients with CS.