About two weeks after a myocardial infarction, which process is most characteristic?

About two weeks after a myocardial infarction, which process is most characteristic?

• A. Coagulative necrosis with neutrophils
• B. Scar from granulation tissue (aneurysm and Dressler's)
• C. Wavy fibers
• D. Fatty infiltration

Answer: (B)

Healing after a myocardial infarction progresses to scar formation around two weeks. At this stage the dead tissue has been cleared and the area is being replaced by fibrous scar tissue that originates from granulation tissue, with fibroblasts laying down collagen and new blood vessels forming. This scar can eventually lead to thinning of the infarcted wall and, in some cases, a left ventricular aneurysm. Dressler’s syndrome, an autoimmune pericarditis that occurs weeks after a MI, may also be seen in this time frame. The other features reflect earlier stages: coagulative necrosis with neutrophils happens in the first few days, wavy fibers are an early histologic sign at the infarct margins, and fatty infiltration is not characteristic of this healing phase.

Healing after a myocardial infarction progresses to scar formation around two weeks. At this stage the dead tissue has been cleared and the area is being replaced by fibrous scar tissue that originates from granulation tissue, with fibroblasts laying down collagen and new blood vessels forming. This scar can eventually lead to thinning of the infarcted wall and, in some cases, a left ventricular aneurysm. Dressler’s syndrome, an autoimmune pericarditis that occurs weeks after a MI, may also be seen in this time frame.

The other features reflect earlier stages: coagulative necrosis with neutrophils happens in the first few days, wavy fibers are an early histologic sign at the infarct margins, and fatty infiltration is not characteristic of this healing phase.