A 54-year-old man has crescendo chest pain at rest lasting 20 minutes. Troponin T is within normal limits and ECG shows transient ST depression. Coronary angiography shows a 90% stenosis of the proximal LAD. Which pathological event best explains his presentation?
- A Complete occlusive thrombus over a ruptured plaque causing transmural necrosis
- B Plaque disruption with partially occlusive thrombus and embolic microinfarcts ✓
- C Coronary vasospasm of an angiographically normal segment
- D Stable fibrotic plaque with gradual luminal narrowing by smooth muscle proliferation
Correct answer: B. Plaque disruption with partially occlusive thrombus and embolic microinfarcts
Explanation
Unstable angina results from disruption of an unstable plaque with superimposed partial thrombosis and distal embolization of small platelet aggregates, producing episodic ischemia without myocyte necrosis, hence normal troponins. Complete occlusive thrombus causes actual infarction with troponin release, killing option A. Vasospasm of a normal segment defines variant or Prinzmetal angina, not rest pain with a fixed critical stenosis.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
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