A 58-year-old man undergoes pharmacologic stress testing with adenosine for evaluation of stable angina. During infusion, he develops severe chest pain and ECG shows ST depression in leads V3-V5. Coronary angiography reveals a critical stenosis in the mid-LAD and a 70% stenosis in the proximal LCx. Which phenomenon explains the ischemia pattern?
- A Coronary steal syndrome ✓
- B Coronary vasospasm
- C Microvascular angina
- D Myocardial bridging
Correct answer: A. Coronary steal syndrome
Explanation
Coronary steal occurs during pharmacologic stress testing when vasodilators (adenosine, dipyridamole) dilate normal coronary arteries, diverting blood flow away from stenotic vessels that are already maximally dilated, causing ischemia in the territory supplied by the stenotic artery. This is the basis of pharmacologic stress testing. Coronary vasospasm is not related to pharmacologic vasodilators. Microvascular angina involves dysfunction of small resistance vessels. Myocardial bridging causes systolic compression.
Reference: Braunwald's Heart Disease, 12th ed.
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