Myocardial fibrosis

Radiopaedia • CC-by-nc-sa 3.0 • de

Myocardial fibrosis refers to an increase in collagen volume within the extracellular interstitium .

Clinical presentation

Myocardial fibrosis leads to diastolic and or systolic dysfunction and patients can present with symptoms associated with cardiac insufficiency arrhythmias such as dyspnea, orthopnea, edema, etc.

Pathology

Fibrosis can be diffuse or focal and can be as a result of different mechanisms :

  • reactive interstitial fibrosis
  • infiltrative interstitial fibrosis
  • replacement fibrosis and myocardial scarring

Progressive increase of the extracellular matrix leads to diastolic and systolic dysfunction and to an increase of adverse cardiovascular events . In end-stage heart failure, myocardial fibrosis is always present  .

Etiology

Myocardial fibrosis can occur as a result of various cardiac diseases (classified by subtypes):

Reactive interstitial fibrosis

due to accelerated collagen synthesis as a result of different stimuli

Infiltrative interstitial fibrosis

progressive deposit of protein or glycosphingolipids

Replacement fibrosis

Due to cell damage or necrosis, an intense inflammatory response is induced, which leads to degradation of the normal interstitial matrix and generation of new matrix fragments thus an alteration of tissue composition .

Radiographic features

MRI

Fibrosis leads to an increase in extracellular volume (ECV), thus to an increased volume of distribution for contrast agents and to an increased shortening in postcontrast T1 .

Signal characteristics
  • T2/STIR: normal
  • IRGRE/PSIR: It can be seen as a late gadolinium enhancement (LGE) in focal disease. Due to the “nulling” of the myocardium in inversion-recovery sequences, it will be difficult to detect diffuse fibrosis .
  • T2 mapping: normal T2 [ms]
  • T1 mapping: increased T1 [ms]
  • ECV: increased

See also