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Functional significance of recruitable collaterals during temporary coronary occlusion evaluated by 99mTc-sestamibi
N P Sand1, M Rehling, J P Bagger
1Department of Nuclear Medicine, Aarhus University Hospital, Skejby Sygehus, Denmark.
Insights
Recruitable collaterals significantly improve myocardial perfusion during temporary coronary artery occlusion, as shown by 99mTc-sestamibi SPECT imaging. This protective effect reduces hypoperfusion in patients with coronary artery stenosis.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Recruitable collaterals play a protective role in myocardial perfusion during percutaneous transluminal coronary angioplasty (PTCA).
- Clinical and hemodynamic data suggest collateral function influences outcomes in coronary artery disease.
Purpose of the Study:
- To evaluate the impact of recruitable collaterals on regional myocardial perfusion during temporary coronary occlusion.
- To correlate perfusion estimates with coronary wedge pressure and ST-segment changes.
Main Methods:
- 30 patients with stable angina and LAD stenosis underwent 99mTc-sestamibi SPECT during 90-s LAD occlusions.
- Coronary wedge pressure and ST-segment changes were recorded.
- An occlusion/rest count ratio estimated regional hypoperfusion.
Main Results:
- Patients with recruitable collaterals showed a higher occlusion/rest count ratio (67%) compared to those without (60%).
- The ratio correlated with coronary wedge pressure (R2=0.34).
- A lower ratio was observed in patients with ST-segment elevation (61%) versus those without (74%).
Conclusions:
- 99mTc-sestamibi SPECT during brief coronary occlusion effectively assesses myocardial hypoperfusion.
- Recruitable collaterals significantly reduce the severity of regional myocardial hypoperfusion in patients with proximal LAD stenosis.
- These findings confirm the protective role of collaterals during temporary coronary occlusion.
Objectives:
The present study evaluated the impact of recruitable collaterals on regional myocardial perfusion measured by 99mtechnetium (Tc)-sestamibi single-photon emission computerized tomography (SPECT) during temporary coronary occlusion and related these estimates to the coronary wedge pressure and electrocardiographic (ECG) ST-segment changes.
Background:
Clinical variables (angina and ECG changes) and intracoronary flow and pressure recordings have indicated a protective role of recruitable collaterals on myocardial perfusion during percutaneous transluminal coronary angioplasty (PTCA).
Methods:
Thirty patients (mean age 55 years, SD 9; 20 men) with stable angina pectoris and proximal nonocluding single-vessel left anterior descending coronary artery (LAD)-stenosis scheduled for PTCA were included. Visualization of recruitable collaterals by ipsilateral and contralateral contrast injection, registration of coronary wedge pressure and injection of 99mTc-sestamibi during 90-s LAD occlusions were undertaken. A rest perfusion study was performed within four days before PTCA. As an estimate of the severity of regional hypoperfusion during occlusion, an occlusion/rest count ratio was calculated (mean defect pixel count during occlusion divided by mean pixel count in identical regions at rest).
Results:
The scintigraphic occlusion/rest count ratio was higher in patients with recruitable collaterals (n = 16), 67 +/- 11%, compared to patients without collaterals (n = 14), 60 +/- 6% (p < 0.05). The occlusion/rest count ratio correlated with the coronary wedge pressure (R2 = 0.34; p < 0.001). The occlusion/rest count ratio was lower, 61 +/- 6%, in patients with ST-segment elevation (n = 23) versus 74 +/- 9% in patients without ST-segment elevation (n = 7) (p < 0.0001).
Conclusions:
Using 99mTc-sestamibi SPECT imaging during brief episodes of coronary occlusion, the severity of regional myocardial hypoperfusion was reduced by the presence of recruitable collaterals in a selected patient population with proximal LAD stenoses. Our results demonstrate a protective effect of recruitable collaterals on myocardial perfusion during temporary coronary occlusion.