Long time follow-up of patients with cardiac sarcoidosis by F-18 FDG PET/CT

Objectives Cardiac sudden death is the leading cause of mortality in patients (pts) with sarcoidosis. Starting corticosteroid treatment before the occurrence of severe systolic dysfunction results in excellent clinical outcome, but there have been no appropriate biomarker for determining the time of initiation and discontinuing the treatment. The aim is to assess the value of FDG PET/CT for follow-up of cardiac sarcoidosis during and after steroid therapy.

Methods Twenty pts who met the Japanese Ministry of Health and Welfare criteria for diagnosing cardiac sarcoidosis (7 men and 13 women; age 57±13 y) prospectively underwent FDG PET/CT and were followed-up for 23±9.2 months. In order to reduce physiological uptake of FDG in the myocardium, its injections were performed after 18.6±0.9 h of overnight fasting. Also we administered unfractionated heparin (50 IU/kg) 15 min before injections to further reduce myocardial uptake of FDG. A maximum standard uptake value (SUVmax) in the heart and a SUVmean in the ascending aorta were obtained on the fusion images and a heart-to-blood (H/B) SUV ratio was calculated.

Results Serum levels of insulin were suppressed, while those of free fatty acid were significantly elevated compared to baseline (p<0.001). Nine pts exhibited focal, 9 exhibited focal on diffuse, and 2 exhibited diffuse myocardial uptake of FDG on the first PET/CT imaging. In 17 pts who underwent PET/CT at baseline and 2 months after corticosteroid therapy (30mg/day), myocardial uptake of FDG significantly decreased from 8.2±3.0 to 5.4±3.4 (p =0.0012). Fifteen pts exhibited ‘none’ pattern (i.e. H/B ratio<2.0) at least once during the follow-up period. However, 10 pts relapsed with significant cardiac accumulation of FDG and received a pacemaker and/or implantable cardioverter-defibrillator.

Conclusions Thus, follow-up FDG PET/CT may effectively guide further treatment and estimate prognosis of cardiac sarcoidosis