A 54-year-old man has crescendo chest pain occurring at rest. Troponin T measured twice, 6 hours apart, is within normal limits. Coronary angiography shows a 90 percent stenosis of the proximal LAD without complete occlusion. Which pathological process best explains his presentation?

• A Stable fibrofatty plaque with luminal narrowing exceeding 75 percent
• B Transient coronary spasm of an angiographically normal segment
• C Occlusive thrombus superimposed on a disrupted plaque causing transmural necrosis
• D Plaque erosion or fissuring with a partially occlusive platelet-rich thrombus ✓

Explanation

Unstable angina is caused by abrupt plaque change, either erosion or fissure, that triggers a largely platelet-rich mural thrombus which does not fully occlude the vessel. Because perfusion is maintained, no myocardial necrosis occurs and troponin remains normal, exactly as here. A stable plaque with fixed critical stenosis produces exertional angina relieved by rest, not rest pain. Complete occlusive thrombus defines STEMI or NSTEMI depending on collaterals. Pure vasospasm is variant (Prinzmetal) angina, which responds to vasodilators and is not tied to a 90 percent fixed stenosis.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.