Myocardial fibrosis leads to impaired diastolic and systolic function and is associated with increased major adverse cardiovascular events. It is a structural correlate that can be found in the different stages of heart failure. The two main types of myocardial fibrosis are interstitial fibrosis and replacement fibrosis. Interstitial fibrosis is a reversible process that occurs early in the disease process as increased collagen synthesis in diffuse microscopic distribution within the myocardium and sometimes by localized perivascular distribution. Replacement fibrosis typically occurs in the later stages of the disease after irreversible myocyte injury or death, in which cell apoptosis triggers fibroblasts and promotes macroscopic deposition of collagen fibrous tissue in the myocardium.

Cardiac magnetic resonance (CMR) has the capability to accurately quantify ventricular volumes and ejection fraction, as well as the non-invasive characterization of the myocardium. These unique features have led to the increased use of CMR in the assessment of patients with heart failure (HF). CMR can detect the presence and extent of replacement fibrosis through late gadolinium enhancement imaging and diffuse interstitial fibrosis through native T1 mapping. Interstitial fibrosis identified by native T1 mapping has been used as a marker of disease activity,^– risk stratification and monitoring of the therapeutic management in heart failure patients.

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