Relation of Left Ventricular Diastolic Function to Global Fibrosis Burden

Left ventricular (LV) diastolic function is primarily assessed by means of echocardiography, which has limited utility in detecting fibrosis. Cardiac magnetic resonance (CMR) readily detects and quantifies fibrosis. In this study, the authors sought to determine the association of LV diastolic function by echocardiography with CMR-determined global fibrosis burden and the incremental value of fibrosis with diastolic function grade in prediction of total mortality and heart failure hospitalizations. A total of 549 patients underwent comprehensive echocardiography and CMR within 30 days. Echocardiography was used to assess LV diastolic function, and CMR was used to determine LV volumes, mass, ejection fraction, replacement fibrosis, and percentage extracellular volume fraction (ECV). Normal diastolic function was present in 142 patients; the rest had diastolic dysfunction grades I to III, except for 18 (3.3%) with indeterminate results. The event rate was higher in patients with diastolic dysfunction compared with patients with normal diastolic function (33.4% vs 15.5; P < 0.001). The model including LV diastolic function grades II and III predicted composite outcome (C-statistic: 0.71; 95% CI: 0.67-0.76), which increased by adding global fibrosis burden (C-statistic: 0.74, 95% CI: 0.70-0.78; P = 0.02). For heart failure hospitalizations, the competing risk model with LV diastolic function grades II and III was good (C-statistic: 0.78; 95% CI: 0.74-0.83) and increased significantly with the addition of global fibrosis burden (C-statistic: 0.80; 95% CI: 0.76-0.85; P = 0.03). Higher grades of diastolic dysfunction are seen in patients with replacement fibrosis and increased ECV. Fibrosis burden as determined with the use of CMR provides incremental prognostic information to echocardiographic evaluation of LV diastolic function.