Comparison of Cardiac MRI and 18F-FDG Positron Emission Tomography Manifestations and Regional Response to Corticosteroid Therapy in Newly Diagnosed Cardiac Sarcoidosis with Complet Heart Block

Background: 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.

Objective: 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.

Methods: 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.

Results: 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.

Conclusion: 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.