Failure of steroid withdrawal guided by 18F-FDG PET in a patient with cardiac sarcoidosis.

A 71-year-old man diagnosed with cardiac sarcoidosis (CS) 11 years previously underwent implantation of an implantable cardioverter defibrillator due to sustained ventricular tachycardia. Over past decade, his condition of CS did not progress on the maintenance steroid dose of 7.5 mg per day. We attempted to taper and discontinue steroids according to the results of fluorine-18-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET). On the basis of the results, we reduced the oral steroid dose slowly. In spite of no abnormal ¹⁸F-FDG uptake in the myocardium, advanced atrioventricular conduction block and deterioration of the ventricular pacing threshold occurred during the course of steroid withdrawal. Plasma brain natriuretic peptide (BNP) increased from 94 to 842 pg/ml. It was necessary to add new ventricular and atrial leads to synchronize atrial and ventricular contractions, and the pacing mode for bradycardia was changed to dual-chamber DDD-60 ppm. Fatigue disappeared, and BNP levels decreased to 147 pg/ml. ¹⁸F-FDG PET might have a limit to detect small scattered inflammatory foci. This case highlights the need for caution when reducing steroid doses in CS patients, guided by ¹⁸F-FDG PET only. <Learning objective:¹⁸F-FDG PET plays an important role in the evaluation of the activity of inflammation and to guide immunosuppression in patients with cardiac sarcoidosis (CS). However, it is unknown whether we can taper and stop corticosteroids when abnormal ¹⁸F-FDG uptake in the myocardium is not seen at every examination. We present a case of CS that failed to taper corticosteroids guided by ¹⁸F-FDG PET. Usefulness and limitation of ¹⁸F-FDG PET in CS are also discussed.>.