Cardiac sarcoidosis (CS) is a rare but potentially severe granulomatous inflammatory disease of unknown etiology, capable of causing arrhythmias, heart failure, or sudden cardiac death. Despite diagnostic progress, major uncertainties remain regarding disease evolution, relapse frequency, therapeutic response, and the comparative value of emerging metabolic imaging tracers. This thesis presents an in-depth retrospective analysis of patients followed at Geneva University Hospitals between January 2016 and December 2024. It addresses five objectives: (1) to determine the incidence of cardiac relapses and their predictive factors; (2) to evaluate the rate of major adverse cardiovascular events (MACE) and their determinants; (3) to assess the efficacy and tolerability of anti-TNF agents; (4) to compare the performance of ¹⁸F-FDG and ⁶⁸Ga-DOTATATE PET for detecting active myocardial inflammation; and (5) to evaluate activation of the mTOR pathway in endomyocardial biopsies.