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Myocardial perfusion and ventricular function measurements during total coronary artery occlusion in humans. A
S Borges-Neto1, J Puma, R H Jones
1Department of Radiology (Nuclear Medicine), Duke University Medical Center, Durham, NC.
Insights
Coronary artery occlusion causes greater myocardial perfusion and function abnormalities than exercise stress tests. This suggests stress tests may underestimate the full impact of coronary stenosis on heart muscle.
Area of Science:
- Cardiology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Radionuclide studies assess coronary artery disease (CAD) by comparing exercise-induced deficits with coronary blood flow.
- Exercise mimics increased myocardial demand, while occlusion represents decreased supply, both relevant to CAD.
- Previous studies have not quantified exercise vs. total occlusion effects on myocardial perfusion and function.
Purpose of the Study:
- To compare the magnitude of changes in myocardial perfusion and function during exercise versus total coronary artery occlusion.
- To evaluate the relationship between exercise-induced ischemia and the potential myocardium at risk from coronary stenosis.
Main Methods:
- Prospective study of 20 patients with significant coronary artery stenosis (>50% diameter).
- Same-day rest/exercise technetium-99m sestamibi myocardial perfusion and function studies.
- Comparison of perfusion and function before and during 1-minute balloon occlusion prior to percutaneous transluminal coronary angioplasty.
Main Results:
- Perfusion defect size was significantly larger during occlusion (28%) compared to exercise (13%) (P < .01).
- Ejection fraction was significantly lower during occlusion (41%) compared to exercise (53%) (P < .01).
Conclusions:
- Total coronary artery occlusion induces more severe physiological abnormalities than exercise stress.
- Stress-induced ischemia may not fully represent the myocardium at risk from coronary stenosis if sudden occlusion occurs.
Background:
The purpose of this investigation was to compare the magnitude of change in myocardial perfusion and function during exercise with that obtained during total coronary artery occlusion. Radionuclide studies are widely used for the diagnosis and determination of prognosis in patients with suspected or known coronary artery disease. These studies are based on the premise that the relative deficit of coronary blood flow, which is induced by exercise and recognized as increased demand, relates to the jeopardy experienced by the decrease or sudden absolute interruption of coronary blood flow that is recognized as decreased supply and is associated with coronary stenosis or total coronary artery occlusion. The magnitude of exercise-induced perfusion and function abnormalities compared with those induced by total coronary artery occlusion in humans has not been previously reported.
Methods And Results:
We prospectively studied 20 patients with > or = 50% diameter stenosis documented by quantitative coronary angiography in at least one vessel. A same-day rest/exercise sestamibi myocardial function and perfusion study was performed within 24 hours before percutaneous transluminal coronary angioplasty. At 1 minute after balloon inflation, while the vessel was occluded, sestamibi was injected, and a myocardial perfusion and function study was performed. Perfusion defect size was greater during occlusion (28 +/- 3%) than during exercise (13 +/- 2%) (P < .01). Ejection fraction was greater during exercise (53 +/- 3%) compared with values measured during occlusion (41 +/- 2%) (P < .01).
Conclusions:
Physiological abnormalities induced by coronary occlusion are greater than those that occur during exercise, thereby indicating that stress-induced ischemia may not reflect the total potential myocardium in jeopardy from a stenotic lesion, if sudden occlusion occurs.