Isolated and non-isolated cardiac sarcoidosis, with differences in cardiac FDG uptake but similar prognosis

Introduction: We divided patients with cardiac sarcoidosis (CS) into isolated type (ICS) and non-isolated type (NICS), and investigated ¹⁸F-FDG (FDG) PET/CT findings of cardiac lesions and their prognosis.

Methods: 31 ICS patients (21men and 10 women) and 92 NICS patients (26 men and 66 women) were enrolled in this study. We compared pre-treatment FDG-PET/CT finding, treatment response, and the occurrence of recurrence and major adverse cardiac event (MACE) between ICS and NICS patients.

Results: Focal accumulation pattern was dominantly observed than focal on diffuse (FD) pattern in both ICS (74.1%) and NICS (64.1%) patients. Right ventricular involvement was significantly frequent in NICS patients than ICS patients (44.6% vs. 0.03%, p < 0.0001). SUVmax and cardiac metabolic activity were significantly higher in NICS patients than ICS patients (SUVmax, 8.9±4.2 vs. 4.8±2.1, p < 0.0001; cardiac metabolic activity, 54.9±69.5cm³ vs. 24.4±46.3cm³, p < 0.0001). Treatment responses were better in cardiac lesions than in extra-cardiac lesions, and the disappearance rate of FDG accumulation after treatment was significantly higher in cardiac lesions (72.2% for ICS, 77.1% for NCIS) than extra-cardiac lesions (34.0%, p < 0.001 for both). However, the recurrence rates were similar among cardiac lesions (30.8% for ICS, 40.5% for NCIS) and extra-cardiac lesions (37.5%) during follow-up period (> 2 years). MACE occurred in 33.3% of ICS patients, and 35.7% of NICS patients, and no significant difference was found between the two groups.

Conclusions: Cardiac lesion in NICS showed more intense and more extensive accumulation on FDG-PET/CT than that in ICS. However, the two groups showed similar prognosis.