Cardiac Sarcoidosis Presenting as Complete Atrioventricular Block: Findings on PET/MRI.

A 72-year-old male was transferred from a health promotion center with complete atrioventricular block (CAVB, Figure 1A). He complained of dyspnea, and had a 1-year history of hypertension and 50 pack-year history of smoking. A whole body fluorodeoxyglucose (FDG) positron emission tomography/magnetic resonance imaging (PET/MRI), taken during a medical check-up, revealed multiple supraclavicular and mediastinal lymphadenopathies, and a hot FDG uptake in the septal area of the heart (Figure 1B, arrow). An FDG cardiac PET/MRI was performed for a further evaluation 3 weeks later. The PET/MRI revealed a late gadolinium enhancement (LGE) in the mid-wall of the basal septum (Figure 1C and 1D, arrowheads) with a corresponding FDG uptake (Figure 1E and 1F, arrowheads). Bronchoscopy was performed for an endobronchial ultrasound guided lymph node (LN) biopsy, and an endobronchial mass was incidentally found in the right upper apical segment. The endobronchial mass was confirmed as a squamous cell carcinoma. A permanent pacemaker implantation was performed with steroid therapy under planning for an operation. A right upper lobectomy was performed with a mediastinal LN dissection (2R, 4R, 10R, 3A, 7, 8, and 9) by video-assisted thoracoscopic surgery. The LN biopsy revealed chronic granulomatous inflammation without a tumor metastasis. He had a final diagnosis of sarcoidosis involving the heart and mediastinal LN, concurrent with lung cancer.

Figure 1

(A) Electrocardiogram; PET/MRI. (B) A whole-body image of the FDG uptake. T1-weighted image; (C) short-axis and (D) long-axis, and cardiac PET/MRI image; (E) short-axis and (F) long-axis.

FDG = fluorodeoxyglucose; MRI = magnetic resonance imaging; PET = positron emission tomography.

In this case, the cardiac PET/MRI well-visualized the myocardial inflammation and fibrosis related to the CAVB. Comprehensive imaging with cardiac PET/MRI could be the gold standard for a clinical diagnosis1)2) in cardiac sarcoidosis.