Histology Course A IV 11 Department of Pathology, University of Zurich Histokurs

A IV 11 subacute myocardial infarction HE further information (German) on HiPaKu 
  ICD-10: I21.3
56-year-old male had a heart attack with cardiogenic shock 15 days prior to death. Death was caused by external rupture of the infarct with consecutive cardiac tamponade. (Specimen from autopsy).
- Subendocardial scar outlined by an irregular, serrated border. Inside this area, the cardiac muscle tissue is partly replaced by a loose granulation tissue consisting of capillaries, fibroblasts, macrophages and necrotic muscle fibres. A more dense collagenous fibrous tissue is observed in some locations (scar formation).
- Heart muscle fibres exhibiting contraction bands are detected adjacent to the granulation tissue.
- A band of myocytes remained viable immediately beneath the endocardium. The subendocardial myocardium is nourished by diffusion from luminal blood.

See also Slide A II 16, A III 14