A 45-year-old man undergoes myocardial perfusion scintigraphy with Tc-99m sestamibi during pharmacological stress and again at rest. The stress images show a large perfusion defect in the anterior wall that completely normalizes on the resting images. This finding represents:
- A Transmural scar from old myocardial infarction
- B Hibernating myocardium requiring revascularization
- C Inducible myocardial ischaemia in the territory of the left anterior descending artery ✓
- D Normal physiological response to vasodilator stress
Correct answer: C. Inducible myocardial ischaemia in the territory of the left anterior descending artery
Explanation
Sestamibi distributes proportionally to coronary blood flow. A defect present during stress but absent at rest indicates flow limitation only at peak demand, which is inducible ischaemia in the supplied vascular territory, here the LAD given the anterior wall location. A fixed defect seen identically on both studies denotes infarcted scar. Hibernating myocardium refers to dysfunctional but viable myocardium, assessed better with metabolic imaging or rest-redistribution protocols.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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