Transient Ischemic Dilation (TID) on Gated SPECT
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Question
A reversible (stress-induced) lateral wall perfusion defect is identified on gated SPECT. The LVEF is 55% at rest and drops to 42% during pharmacologic stress. This stress-induced reduction in LVEF (>5% drop) is called:
- ANormal stress response
- BHypertensive response to pharmacologic stress
- CTechnical artifact from gating error
- DTransient ischemic dilation (TID) or stress-induced LVEF drop — marker of severe CAD
Show the answer and explanation
D. Transient ischemic dilation (TID) or stress-induced LVEF drop — marker of severe CAD
A drop in LVEF of ≥5% from rest to stress on gated SPECT (or transient ischemic dilation of the LV cavity at stress) is a marker of hemodynamically significant, often multivessel or left main coronary artery disease. It indicates that the ischemic burden is large enough to impair global LV function during stress. This finding upgrades risk even when the perfusion defect appears limited to one territory. Combined with a reversible lateral wall defect, it suggests significant LCX territory ischemia with impact on global function.
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