Myocardial fibrosis

Author: Mikael Häggström

Presentations

Fibrosis, in this case an old myocardial infarction of the posterior wall of the left ventricle (seen as pale areas).

Fibrosis consistent with old myocardial infarction, after formalin fixation.

• Heart, autopsy thereof and/or autopsy of myocardial infarction.

Microscopic evaluation

In case of myocardial fibrosis, attempt to distinguish between the following:

• Interstitial fibrosis, which is unspecific, (and may simply reported as such).
• Subepicardial fibrosis, also unspecific (and may simply be reported as such).
• Replacement fibrosis, which indicates an older infarction.

• 
  Healthy myocardium versus interstitial fibrosis in dilated cardiomyopathy. Alcian blue stain. The fibrosis is either evenly distributed between myocytes or follows anatomic structures such as blood vessels.
• 
  Interstitial fibrosis of chronic ischemic heart disease, H&E stain, with associated relatively well organized myocardial bundles, with rather rounded interfaces between myocyte bundles and fibrosis.
• 
  Subepicardial fibrosis (epicardium at top).
• 
  Replacement fibrosis in myocardial infarction, typically displaying sharp interfaces between myocytes and fibrosis, and being more boundless and dense.

Reporting

Example (if uncertain whether there is replacement fibrosis or merely subepicardial fibrosis):

Fibrosis of mainly replacement-type which may indicate an older infarction.

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