A 74-year-old woman presents with acute chest pain and shortness of breath. Cardiac catheterization demonstrates occlusion of the left anterior descending coronary artery. Laboratory studies and ECG are consistent with acute myocardial infarction. Which of the following is the most likely pathologic finding in the affected heart muscle 4 weeks later?
Capillary-rich granulation tissue
Collagen-rich scar tissue
Neutrophils and necrotic debris
Answer:B Collagen-rich scar tissue
Pathologic findings in congestive heart failure include microscopic signs of coagulative necrosis approximately 24 hours after the onset of vascular occlusion.
Polymorphonuclear leukocytes and macrophages predominate during the next 2 to 5 days .
Towards the end of the first week, the infarct is invaded by capillary rich granulation tissue.
Ultimately, the necrotic myocardium is replaced by collagen-rich scar tissue (weeks to months).
Granulomatous inflammation does not occur after an ischemic myocardial infarct. Vascular congestion & edema are features of acute inflammation.