139 of imaging in detecting granulomatous inflammation but acknowledge the limitations in identifying SCAD.7 If diagnostic evaluation using CMR and PET fails to detect cardiac sarcoidosis despite persistent symptoms, SCAD should be considered. SCAD involves dysregulation of heart function by the autonomic nervous system.9 It may result in symptoms such as palpitations, syncope, dizziness, or exercise intolerance, and can lead to severe complications, including arrhythmias and sudden cardiac death.10 However, the condition’s insidious nature may leave patients asymptomatic for extended periods.11 Cardiac autonomic dysfunction is a serious but often overlooked complication of sarcoidosis and is frequently associated with SFN.12,13 Diagnostic tools include cardiovagal testing, such as the Ewing battery,14 stress-based assessments like the cold pressor test,15 and imaging modalities like [123I]-meta-iodinebenzylguanidine ([123I]-MIBG) scintigraphy.12,16,17 [123I]MIBG scintigraphy might be of additional value for patients with specific symptom patterns and unremarkable cardiac FDG PET/CT or MRI findings or for cases where symptoms persist despite immunosuppressive therapy. Carvedilol, a β-blocker with additional antioxidant and anti-inflammatory properties, is occasionally used to enhance parasympathetic activity, restore autonomic balance and reduce symptoms.12,18,19 While CMR and FDG PET/CT are both invaluable in the assessment of cardiac sarcoidosis,8 the integration of [123I]MIBG scintigraphy offers a complementary role that warrants attention. MIBG scintigraphy provides unique insights into myocardial sympathetic innervation, which can be altered in cardiac sarcoidosis due to the involvement of the autonomic nervous system.16 It can help by identifying areas of impaired myocardial sympathetic function, even in the absence of structural changes detectable by CMR or FDG PET/CT. Recognizing the added value of MIBG in conjunction with CMR and FDG PET/CT may lead to more comprehensive and personalized management of patients with suspected cardiac sarcoidosis. Therefore, the aim of this retrospective study is to evaluate the value of [123I]MIBG scintigraphy in diagnosing SCAD in patients with unexplained cardiac symptoms. Specifically, we aim to determine whether [123I]MIBG scintigraphy offers additional diagnostic insights in cases where traditional imaging modalities, such as FDG PET/CT and CMR, fail to detect evidence of cardiac sarcoidosis. Methods Study design and subjects This retrospective study included patients with sarcoidosis who were referred to the outpatient clinic of St. Antonius hospital, a tertiary referral center for sarcoidosis and interstitial lung diseases (ILD) in the Netherlands, and underwent [123I]MIBG scintigraphy between October 2017 and February 2024. The diagnosis sarcoidosis was confirmed following international guidelines.1 Patient characteristics in combination with results from FDG PET/CT, CMR as well as [123I]MIBG scintigraphy were discussed in a multidisciplinary team (MDT) consisting of pulmonologist, cardiologists and nuclear medicine specialists. Measurements Diagnosis of cardiac sarcoidosis Diagnosis of cardiac sarcoidosis was made according the Heart Rhythm Society (HRS) expert consensus criteria.8 Both definite and probable cardiac sarcoidosis were classified as cardiac sarcoidosis, mainly as both outcomes are comparable.20 Diagnosis of cardiac sarcoidosis 9 145 9
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