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

ObjectivesThe 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.BackgroundThe precise mechanism of LV diastolic dysfunction in the presence of myocardial fibrosis has not previously been established.MethodsWe performed CMR with T1 mapping and obtained invasive LV PV measurements via a conductance catheter in 20 cardiac transplant recipients at the time of clinically-indicated coronary angiography.ResultsBoth post-contrast myocardial T1 time and extracellular volume fraction correlated with β, 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 T1 time remained the only independent predictor of β. No significant associations were observed between myocardial T1 time and τ, the active LV relaxation constant, or other load-dependent parameters of diastolic function.ConclusionsDiffuse myocardial fibrosis, assessed by post-contrast myocardial T1 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.