Characterization of the Electroanatomic Substrate in Cardiac Sarcoidosis: Correlation With Imaging Findings of Scar and Inflammation

OBJECTIVES: This study sought to characterize the electroanatomic (EAM) substrate in patients with cardiac sarcoidosis (CS) and ventricular tachycardia and its relationship to imaging findings of inflammation and fibrosis.; BACKGROUND: CS is characterized by coexistence of active inflammation and replacement fibrosis.; METHODS: A total of 42 patients with CS based on established criteria and ventricular tachycardia underwent high-density EAM mapping. Abnormal electrograms (EGM) were collected and independently classified as multicomponentfractionated, isolated, late, and split according to standard criteria and regardless of the peak-to-peak bipolar/unipolar voltage. A total of 29 patients (69%) underwent pre-procedural cardiac magnetic resonance (CMR) and positron emission tomography (PET)/computed tomography (CT). The distribution of EAMsubstrate was correlated with regions of late gadolinium enhancement (LGE) on CMR and increased 18F-fluorodeoxyglucose uptake on PET/CT.; RESULTS: Of 21,451 bipolar and unipolar EGM, 4,073 (19%) were classified as abnormal with a predominant distribution in the basal perivalvular segments and interventricular septum. Using the standard bipolar (<1.5 mV) and unipolar (<8.3mV for left ventricle<5.5 mV for the right) voltage cutoff values, 40% and 22% of the abnormal EGM were located outside the EAM low-voltage areas, respectively. LGE was present in 26 of 29 patients (90%), whereas abnormal 18F-fluorodeoxyglucose uptake in 14 of 29 patients (48%) with imaging. Segments with abnormal EGM had more LGE-evident scar transmurality [median: 24% (interquartile range [IQR]: 4% to 40%) vs. median: 5%(IQR: 0% to 15%); p< 0.001] and lower metabolic activity (median: 20 g glucose [IQR: 14 g to 30 g] vs. median: 29 g glucose [IQR: 18 g to 39 g]; p< 0.001). Overall, the agreement between the presence of abnormal EGM was higher with the presence of LGE (kappa= 0.51; p< 0.001) than with the presence of active inflammation (kappa=-0.12; p= 0.003).; CONCLUSIONS: In patients with CS and ventricular tachycardia, pre-procedural imaging with CMR and PET/CT can be useful in detecting EAM abnormalities that are potential targets for substrate ablation. Abnormal EGM were more likelylocated in segments with more scar transmurality (LGE) at CMR and a lower degree of inflammation on PET. Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.