Cardiac Sarcoidosis Underlies Idiopathic Dilated Cardiomyopathy Importance of Mediastinal Lymphadenopathy in Differential Diagnosis

BACKGROUND: Cardiac sarcoidosis is frequently overlooked or misdiagnosed as idiopathic dilated cardiomyopathy (DCM), primarily because of difficulties in its diagnosis. This is a crucial issue because appropriate therapy with immunosuppressive agents can be initiated if early diagnosis is achieved. METHODS AND RESULTS: Thoracic computed tomography (CT) was retrospectively analyzed in detail with special reference to lymph node swelling (LNS) in the mediastinum of 8 patients diagnosed with idiopathic DCM who underwent left ventriculoplasty (LVP), and were later proven to have active cardiac sarcoidosis by histological evaluation of the resected myocardium. Twenty age-matched patients with idiopathic DCM who also underwent LVP served as controls. On conventional chest radiographs, none of the cardiac sarcoidosis patients exhibited lymph node involvement, including bilateral hilar lymphadenopathy. However, CT demonstrated significant mediastinal LNS in 7 (88%) of them and in only 1 (5%) of the 20 controls. There was a significant difference in the incidence of LNS in the 2 groups (p=0.00005). CONCLUSION: Evaluation of mediastinal lymphadenopathy by CT is an easy and valuable initial screening method for distinguishing cardiac sarcoidosis from idiopathic DCM.