CLINICAL IMPLICATIONS OF FDG-PET IN SUSPECTED CARDIAC SARCOIDOSIS

Abstract

An optimal strategy for diagnosing cardiac sarcoidosis (CS) and monitoring treatment response is lacking. FDG-PET is a highly sensitive and specific test for CS that assesses disease activity, but its additive value to other modalities in the clinical setting remains unclear. To determine the impact of FDG-PET in relation to biopsy, cardiac MRI, and the Japanese Ministry of Health and Welfare (JMHW) criteria on the course of patients with suspected CS. Retrospective cohort study of suspected CS patients who were offered FDG-PET through a limited access feasibility study in the Province of British Columbia. Baseline characteristics, sequence of diagnostic testing, and treatment decisions were examined for patients who underwent FDG-PET between January 2013 and March 2014. Clinical data and FDG-PET results for 20 patients who underwent the scans were available for analysis. Median age was 58 years, and men comprised 60% of the cohort. Nine (45%) patients presented with low EF, 4 (20%) with VT, 4 (20%) with advanced heart block, 2 (10%) with SVT, and 1 (5%) with acute myocarditis. Median EF on echo was 45%, and 12 (60%) patients required ICD, mostly for secondary prevention (9 patients). Of the 13 (65%) patients who underwent cardiac biopsy, 5 (38%) were consistent with sarcoidosis. All biopsy positive patients had normal FDG uptake, however 4 of these patients were already treated prior to their scan. Six (30%) patients had abnormal cardiac FDG uptake, including 2 that had received prior steroid therapy. Five out of 8 patients with negative cardiac biopsy had abnormal cardiac FDG uptake. While 13 (65%) patients had confirmed or high suspicion of CS after multimodality testing and biopsy, only 2 (10%) met the JMHW diagnostic criteria. FDG-PET influenced management in 14 (70%) patients: by helping initiate, continue, or change steroid dosage in 3 (15%) patients, and by allowing discontinuation or lack of initiation of treatment in 11 (55%) patients on the basis of negative FDG-PET. Of the remaining 6 (30%) patients, either no treatment was given despite an abnormal FDG uptake in 2 patients due to clinically silent disease, or treatment decisions were not yet finalized. In our series, FDG-PET aided in treatment decisions in patients suspected of CS. Due to its ability to assess disease activity and monitor response to therapy, FDG-PET adds value beyond conventional testing, and its use is advocated in cases with high suspicion of CS.