Multimodal approach for isolated cardiac sarcoidosis.

We would like to thank Dr Kupari for his interests and incisive comments on our case report of isolated cardiac sarcoidosis associated with coronary vasomotion abnormalities.[1] We diagnosed our patient with isolated cardiac sarcoidosis according to the clinical diagnosis group proposed by the Japanese Circulation Society (JCS) guidelines.[2] We concur with Dr Kupari that isolated cardiac sarcoidosis is a diagnostic challenge[3] and that cardiac magnetic resonance (CMR) and 18F-fluorodeoxygenase positron emission tomography (18F-FDG-PET) do not necessarily have high specificity.[4] A limitation of the aforementioned study by Divakaran et al.[4] is that only 7 (3.4%) patients underwent both pre-transplant CMR and 18F-FDG-PET. Among them, only one patient was classified as ‘highly probable’ for cardiac sarcoidosis consistently by both modalities, and indeed, this single patient was confirmed to be cardiac sarcoidosis by post-transplant histological diagnosis.[4] In addition, the cohort of patients was biased towards those with advanced heart failure undergoing cardiac transplant, in whom the diagnostic accuracy of 18F-FDG-PET in detecting myocardial inflammation may be limited because of altered myocardial glucose metabolism in severe heart failure.[4] As summarized in the Slide Set,[1] clinical presentation, several biomarkers, and an integrated multimodal imaging approach provide additional details and information on the underlying pathophysiology of inflammatory myocardial diseases.[2] In place of just a binary interpretation of findings derived from each imaging modality, the extent, location, pattern, and concordance of late gadolinium enhancement (LGE) and FDG uptake should be evaluated to identify active, inflammatory cardiac sarcoidosis that warrants immunosuppressive therapy without delay.[2,5] Our patient showed a non-ischaemic, ‘highly probable’[4] pattern of LGE on CMR aligning exactly with inflammation by 18F-FDG-PET performed with optimal imaging conditions.[2] Additional clinical findings compatible with isolated cardiac sarcoidosis included (i) typical cardiac manifestations, (ii) no involvement other than the heart, and (iii) regression of FDG uptake on serial 18F-FDG-PET following corticosteroid therapy. Taken together, these results may help distinguish cardiac sarcoidosis from myocarditis in our patient. Further research is needed to validate the diagnostic value of isolated cardiac sarcoidosis in accordance with the JCS guidelines.[2]