Interstitial Fibrosis, Functional Status, and Outcomes in Heart Failure With Preserved Ejection Fraction: Insights From a Prospective Cardiac Magnetic Resonance Imaging Study

Myocardial extracellular volume (ECV) accumulation is one of the key pathophysiologic features of heart failure with preserved ejection fraction (HFpEF). Our aims were to (1) measure ECV by cardiac magnetic resonance T1 mapping using the modified Look-Locker inversion recovery (MOLLI) sequence, (2) validate MOLLI-ECV against histology, and (3) investigate the relationship between MOLLI-ECV and prognosis in HFpEF. One-hundred seventeen consecutive HFpEF patients underwent cardiac magnetic resonance imaging, coronary angiography, and invasive hemodynamic assessments at baseline. Eighteen patients also underwent left ventricular biopsy for histological analysis (Histo-ECV). To assess the prognostic impact of MOLLI-ECV, its association with hospitalization for heart failure/cardiac death was tested by multivariable Cox regression analysis. Histo-ECV was 30.1±4.6% and was significantly correlated with MOLLI-ECV (R=0.494, P=0.037). Patients were followed for 24.0 months (6.0-32.0 months), during which 34 had a cardiac event. By Kaplan-Meier analysis, patients with MOLLI-ECV ≥ the median (28.9%) had shorter event-free survival (log-rank, P=0.028). MOLLI-ECV significantly correlated with N-terminal prohormone of brain natriuretic peptide (P