Isolated cardiac sarcoidosis with rapid progressive ‘malignant’ arrhythmia

A 44-year-old man with dyspnoea was diagnosed with first-degree atrioventricular block (AVB) at the local clinic 20 days ago. After admission to our hospital, second-degree AVB and incomplete right bundle branch block (RBBB) were detected (Panel A). Echocardiography showed normal left ventricular ejection fraction but right ventricular (RV) enlargement and thickened septum. C-reactive protein and Troponin I were elevated but erythrocyte sedimentation rate was normal. Coronary computed tomography angiography and chest computed tomography were negative. Cardiac magnetic resonance (CMR) revealed multiple nodular thickening with high signal intensity on T2-weighted images and apparent late gadolinium enhancement (LGE), predominantly at RV insertion points and RV free wall (Panels C and D), suggesting active inflammatory infiltration. Six days after CMR, Holter turned to persistent third-degree AVB, complete RBBB, and frequent premature ventricular contractions (PVCs; Panel B; Supplementary material online). Based on rapid progressive arrhythmia and CMR findings, cardiac sarcoidosis (CS) was suspected and endomyocardial biopsy further confirmed it by the presence of non-caseating epithelioid granulomas (Panel E). 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) positron emission tomography (PET) demonstrated no abnormal FDG accumulation except for the heart (Panel H). Then, the diagnosis of isolated CS was confirmed. The patient was given hormone pulse and immunosuppressive therapy and soon relieved (see Supplementary material online). Four months after discharge, repeat CMR demonstrated a complete resolving of myocardial oedema as well as a significant reduction of nodular LGE (Panels F and G). Holter showed intermittent AVB and PVC. Cardiac magnetic resonance characteristics, representing active inflammatory infiltration, may provide an insightful perspective for the mechanisms of rapid progressive AVB and a follow-up value of efficacy evaluation. Supplementary material is available at European Heart Journal – Case Reports. Consent: The authors confirm that written consent for submission and publication of this case report including images and associated text has been obtained from the patient in line with COPE guidance.