Myocardial Substrate Characterization by CMR T1 Mapping in Patients With NICM and No LGE Undergoing Catheter Ablation of VT

OBJECTIVES The goal of this study was to characterize the relationship between DF, the electroanatomic mapping (EAM) substrate, and outcomes of catheter ablation of VT in NICM.BACKGROUND A substantial proportion of patients with nonischemic dilated cardiomyopathy (NICM) and ventricular tachycardia (VT) do not have scar detectable by cardiac magnetic resonance late gadolinium enhancement (LGE) imaging. In these patients, the significance of diffuse fibrosis (OF) detected with T-1 mapping has not been previously investigated.METHODS This study included 51 patients with NICM and VT undergoing catheter ablation (median age 55 years; 77% mate subjects) who had no evidence of LGE on pre-procedural cardiac magnetic resonance. Post-contrast T-1 relaxation time determined on the septum was assessed as a surrogate of OF burden. The extent of endocardial tow-voltage areas (LVAs) at EAM was correlated with T-1 mapping data.RESULTS Bipolar LVAs were present in 22 (43%) patients (median extent 15 cm(2) [8 to 29 cm(2)]) and unipotar LVA in all patients (median extent 48 cm 2 [26 to 120 cm(2)]). A significant inverse correlation was found between T-1 values and both unipolar-LVA (R-2 = 0.64; beta = -0.85; p < 0.01) and bipolar-LVA (R-2 = 0.16; beta = -1.63; p < 0.01). After a median follow-up of 45 months (22 to 57 months), 2 (4%) patients died, 3 (6%) underwent heart transplantation, and 8 (16%) experienced VT recurrence. Shorter post-contrast T-1 time was associated with an increased risk of VT recurrence (hazard ratio: 1.16; 95% confidence interval: 1.03 to 1.33 per 10 ms decrease; p = 0.02).CONCLUSIONS In patients with NICM and no evidence of LGE undergoing catheter ablation of VT, DF estimated by using post-contrast T-1 mapping correlates with the voltage abnormality at EAM and seems to affect post-ablation outcomes. (C) 2021 by the American College of Cardiology Foundation.