On histology of a myocardial infarct, which finding is FIRST to appear and at what time after coronary occlusion?
- A Wavy myofiber change and early coagulative necrosis — 0 to 4 hours (earliest change) ✓
- B Coagulative necrosis with loss of nuclei — 6 to 12 hours
- C Granulation tissue with new capillaries — 1 to 2 weeks
- D Dense neutrophil infiltration — 4 to 6 hours
Correct answer: A. Wavy myofiber change and early coagulative necrosis — 0 to 4 hours (earliest change)
Explanation
The earliest histological changes (0–4 hours) in MI are waviness of myofibers at the infarct border and early coagulative necrosis (pale cytoplasm with preserved outlines). Neutrophil infiltration peaks at 24–72 hours. Macrophages arrive at 4–7 days. Granulation tissue forms at 1–2 weeks. Dense fibrosis replaces the infarct by 6–8 weeks.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.