Article Role of Metabolic Imaging in Detecting Cardiac Involvement in Sarcoidosis.

Yoshinaga, Keiichiro

79 ( 12 )  , pp.2551 - 2552 , 2015-12
ISSN:1346-9843
Description
Cardiac sarcoidosis is considered to be a significant cause of advanced atrioventricular (AV) block or ventricular tachyarrhythmia (VT) in the young to middle-aged population.1 The Heart and Rhythm Society (HRS) therefore recently raised the clinical importance of detecting cardiac involvement of sarcoidosis (CS).2 Although the total number of sarcoidosis cases in the Japanese population is limited,3 the frequency of cardiac involvement is significantly higher in the Japanese population than in other populations.4 Therefore, Japanese investigators have worked intensively to develop relevant diagnostic approaches, especially those involving 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET).5–7 Article p 2669 18F-FDG PET is a highly sensitive approach for detecting CS but with a relatively low specificity7 because of the propensity for physiological myocardial 18F-FDG uptake.8 This being the case, JSNC recommendations based on recent studies have suggested preparation involving long fasting and diet modification prior to 18F-FDG PET studies.5,9 Given the challenges associated with 18F-FDG preparation, alternative diagnostic approaches for CS are being sought.In this issue of the Journal, Momose et al assess the diagnostic value of 123I-β-methyl-p-[123I]-iodophenyl-pentadecanoic acid (123I-BMIPP) single-photon emission computed tomography (SPECT) imaging in patients with suspected CS.10 A 123I-BMIPP abnormality reflects the myocardial metabolic shift often seen after the resolution of severe myocardial ischemia, so-called “ischemic memory imaging”, and is considered to be a sign of past myocardial injury.11 The usefulness of 123I-BMIPP for detecting CS has previously been suggested,12 but he strength of the current study by Momose et al lies in the fact that they compared 123I-BMIPP findings to those determined using current state-of-the-art diagnostic testing. Comparing 123I-BMIPP findings with the findings of active inflammation as determined through 18F-FDG PET and those of tissue fibrosis as determined using201 thallium myocardial perfusion imaging13 or cardiac magnetic resonance imaging (CMR), it is apparent that 123I-BMIPP findings may reflect the early phase of myocardial injury following the active inflammation phase (Figure). 123I-BMIPP defects associated with early myocardial injury may appear earlier than the development of scar tissue. The current findings may have 2 important clinical applications. First, 123I-BMIPP may have a complementary diagnostic role for patients with suspected CS who have difficulties with 18F-FDG PET preparation or for patients who have non-diagnostic 18F-FDG PET results because of physiological myocardial 18F-FDG uptake. Second, a 123I-BMIPP defect may contribute to a treatment strategy because a key treatment goal is to prevent scar formation in myocardial tissue. Evaluation of these 2 important clinical issues should therefore be the next step.

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