A 45-year-old man has recurrent chest pain occurring exclusively at rest, often between midnight and early morning. ECG during pain shows transient ST elevation in II, III, and aVF. Which mechanism is responsible?
- A Plaque rupture with superimposed thrombus
- B Coronary artery vasospasm ✓
- C Increased myocardial oxygen demand
- D Microvascular endothelial dysfunction
Correct answer: B. Coronary artery vasospasm
Explanation
Variant (Prinzmetal) angina is caused by focal coronary artery vasospasm, producing transient ST elevation during episodes. It occurs at rest and follows a circadian pattern. Plaque rupture causes ACS with ST elevation or depression. Demand ischemia causes stable angina. Microvascular dysfunction causes INOCA with non-obstructive coronaries.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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