Comparing the Prognostic Utility of Late Gadolinium Enhancement Burden and Phenotype in Patients with Cardiac Sarcoidosis; a Prospective Cohort Study

Introduction Cardiac Sarcoidosis (CS) is associated with a significant risk of Ventricular Arrhythmias (VAs). Recently late gadolinium enhancement (LGE) phenotypes have been described; the ‘pathology-frequent’ phenotype has been shown to be strongly associated with future VA risk. The aim of our study was to compare the relative predictability of quantitative LGE burden and LGE phenotype. Secondary aims were to contrast the reproducibility and speed of LGE burden quantification and LGE phenotyping. Methods This is a two center sub-study of the Cardiac Sarcoidosis Multi-Center Prospective Cohort Study (CHASM-CS; NCT01477359). All patients underwent CMR at baseline. Results A total of 206 patients (112/206 (54.4%) with CS and 94/206 (45.6%) with extra-cardiac sarcoidosis) were included in the study. Pathology-frequent LGE phenotype occurred in 85/206 (41.3%) and 22/206 (10.7%) patients had sustained VA during a mean follow-up period of 5.1±2.8 years. All events occurred in patients with pathology-frequent phenotype. LGE phenotype and categorical LGE% had similar high discriminative accuracy in predicting future VA; however, only LGE phenotyping had 100% NPV. Interobserver reproducibility of LGE phenotype was very high (Cohen's kappa=0.97, p<0.001) and much better than LGE categorical quantification (Cohen's kappa =0.41, p=0.04). LGE phenotyping was on average five-fold faster (1.75 ± 0.9 minutes compared to 10 ± 2.2 minutes, p=0.012) Conclusions Our study confirms, for the first time in a fully prospective cohort, the prognostic importance of the pathology-frequent phenotype of LGE. This phenotype had 100% NPV, indicating the absence of VA events among patients without pathology frequent phenotype. LGE phenotyping showed much higher interobserver reproducibility than LGE quantification and was five-fold faster.