Comparison of cardiac MRI and 18F-FDG positron emission tomography manifestations and regional response to corticosteroid therapy in newly diagnosed cardiac sarcoidosis with complete heart block

Complete heart block (CHB) caused by myocardial inflammation is a serious consequence of cardiac sarcoidosis (CS) that requires early diagnosis for effective anti-inflammatory treatment.This study aimed to clarify the cardiac magnetic resonance imaging (MRI) and (18)F-fluoro-2-deoxyglucose positron emission tomography ((18)F-FDG PET) manifestations of newly diagnosed CS with CHB and to assess whether certain imaging features could predict responders to corticosteroid therapy.Fifteen newly diagnosed CS patients with CHB and 17 without CHB were examined. We defined abnormal (18)F-FDG uptake on (18)F-FDG PET and increased T2-weighted signal on cardiac MRI as signs of myocardial inflammation and delayed enhancement (DE) on cardiac MRI as a sign of myocardial fibrosis. Ten CHB+ patients were then treated with corticosteroids.The CHB+ group showed higher (18)F-FDG uptake and increased T2-weighted signal in the interventricular septum, which involves the electrical pathway of atrioventricular conduction, than the CHB- group (P = .001 and P < .0001, respectively), whereas there was no group difference in DE (P = .232). Six corticosteroid-treated patients recovered from CHB; all had exhibited increased T2-weighted signal, (18)F-FDG uptake, and DE in the interventricular septum before therapy. In contrast, among the 4 patients without recovery, 2 showed no abnormal (18)F-FDG uptake and 3 had no increased T2-weighted signal in the interventricular septum, but all showed DE. The 2 patients without recovery with abnormal (18)F-FDG uptake showed wall thinning in the interventricular septum.Focal inflammation in the interventricular septum was associated with CHB and might predict recovery from CHB after corticosteroids if it coexists with preserved wall thickness.