Relation of Myocardial Contrast-Enhanced T Mapping by Cardiac Magnetic Resonance to Left Ventricular Reverse Remodeling After Cardiac Resynchronization Therapy in Patients With Nonischemic Cardiomyopathy.

Myocardial scar is known to be associated with limited left ventricular (LV) reverse remodeling after cardiac resynchronization therapy (CRT). However, the impact of diffuse myocardial interstitial fibrosis, as assessed with myocardial T mapping cardiac magnetic resonance (CMR), has not been studied in patients with CRT. Therefore, we aimed at evaluating the association between diffuse myocardial interstitial fibrosis, in nonischemic cardiomyopathy patients, and LV reverse remodeling after CRT. A total of 40 patients (61 ± 11 years) with nonischemic cardiomyopathy who underwent CMR before CRT implantation were included. Myocardial T mapping was performed using an inversion-recovery Look-Locker sequence after gadolinium injection. Myocardial contrast-enhanced T time values were assessed from segments without delayed contrast enhancement and normalized for heart rate. At 6-month follow-up, LV reverse remodeling was assessed by the reduction in LV end-systolic volume. Before CRT implantation, mean myocardial contrast-enhanced T time was 351 ± 46 ms. At 6-month follow-up, LV end-systolic volume decreased by 24 ± 21%. Myocardial contrast-enhanced T time showed a significant correlation with LV reverse remodeling (r = 0.5, p = 0.001) together with hemoglobin level, renal function, LV dyssynchrony, and presence of delayed contrast enhancement. Multivariate regression analysis identified myocardial contrast-enhanced T time (β -0.160, p = 0.022), LV dyssynchrony (β -0.267, p = 0.002), and renal function (β -0.334, p = 0.021) as independent associates of LV reverse remodeling. In conclusion, in nonischemic cardiomyopathy, diffuse interstitial myocardial fibrosis quantified with T mapping CMR is independently associated with LV reverse remodeling after CRT and might, therefore, be used to optimize patient selection.