Diffuse Myocardial Fibrosis Evaluated by Post-Contrast T1 Mapping Correlates With Left Ventricular Stiffness

Objectives The purpose of this study was to use cardiac magnetic resonance (CMR) imaging and invasive left ventricular (LV) pressure-volume (PV) measurements to explore the relationship between diffuse myocardial fibrosis and indexes of diastolic performance in a cohort of cardiac transplant recipients. Background The precise mechanism of LV diastolic dysfunction in the presence of myocardial fibrosis has not previously been established. Methods We performed CMR with T-1 mapping and obtained invasive LV PV measurements via a conductance catheter in 20 cardiac transplant recipients at the time of clinically-indicated coronary angiography. Results Both post-contrast myocardial T-1 time and extracellular volume fraction correlated with beta, the load-independent passive LV stiffness constant (r = -0.71, p = 0.001, and r = 0.58, p = 0.04, respectively). After multivariate analysis, post-contrast myocardial T-1 time remained the only independent predictor of b. No significant associations were observed between myocardial T-1 time and tau, the active LV relaxation constant, or other load-dependent parameters of diastolic function. Conclusions Diffuse myocardial fibrosis, assessed by post-contrast myocardial T-1 time, correlates with invasively-demonstrated LV stiffness in cardiac transplant recipients. In patients with increased diffuse myocardial fibrosis, abnormal passive ventricular stiffness is therefore likely to be a major contributor to diastolic dysfunction. (C) 2014 by the American College of Cardiology Foundation