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PET scan predicts recovery of left ventricular function after coronary artery bypass operation
W J Flameng1, B Shivalkar, B Spiessens
1Department of Cardiac Surgery, Katholieke Universiteit Leuven, Belgium.
Insights
Predicting cardiac function recovery after revascularization is key. Identifying myocardial viability using mismatch regions on PET scans significantly predicts improved ejection fraction post-surgery in three-vessel disease patients.
Area of Science:
- Cardiology
- Nuclear Medicine
- Cardiac Imaging
Background:
- Myocardial hibernation, viable but hypocontractile heart muscle, can improve post-revascularization.
- Predicting functional recovery in severe left ventricular dysfunction is challenging.
- Identifying predictors of cardiac function recovery after revascularization in three-vessel disease is crucial.
Purpose of the Study:
- To identify predictive factors for cardiac function recovery after revascularization in patients with three-vessel disease.
Main Methods:
- Positron emission tomography (PET) for metabolism (fluoro-18-deoxyglucose) and flow (nitrogen 13-labeled ammonia) was used.
- Equilibrium-gated nuclear angiography assessed global ejection fraction.
- PET data categorized regions as match normal, mismatch, match viable, or match necrosis.
Main Results:
- Mismatch regions (low flow, high metabolism) were significant predictors of postoperative functional improvement (p = 0.019).
- Patients with improvement had more mismatch regions (1.7 +/- 1.5) than those without (0.8 +/- 1.0).
- A higher number of mismatch regions correlated with greater functional improvement; at least one mismatch region predicted recovery (p < 0.001).
Conclusions:
- The presence of at least one myocardial mismatch region is necessary for functional benefit after revascularization.
- Significant early recovery was observed in patients with low ejection fraction and two or more mismatch regions.
Background:
Viable but hypocontractile myocardium can show functional improvement after revascularization (hibernation). It is sometimes difficult, however, to predict viability and recovery in patients with severe left ventricular function. This study sought to identify possible predictive factors of recovery of cardiac function after revascularization in patients with three-vessel disease.
Methods:
Positron emission tomography (fluoro-18-deoxyglucose uptake for metabolism; nitrogen 13-labeled ammonia for flow) and equilibrium-gated nuclear angiography (for the global ejection fraction) were performed in 59 patients with three-vessel disease before and after undergoing coronary artery bypass grafting. The positron emission tomographic data were expressed as match normal (flow and metabolism normal), mismatch (low flow, high metabolism), match viable (moderate decrease in flow and metabolism), and match necrosis (low flow and metabolism).
Results:
Stepwise logistic regression analysis showed that only mismatch regions played a significant role in predicting postoperative improvement in function (p = 0.019). There were 1.7 +/- 1.5 mismatch regions in 31 patients who showed an improvement in their ejection fraction (0.47 +/- 0.14 versus 0.58 +/- 0.11; mean +/- standard deviation) versus 0.8 +/- 1.0 mismatch regions (p = 0.017) in patients who did not show recovery. There was more pronounced functional improvement with increasing numbers of mismatch regions, and patients with at least one mismatch region had a high likelihood of recovery (p < 0.001). In patients with a very low preoperative ejection fraction and two or more mismatch regions, there was early significant recovery (0.27 +/- 0.08 versus 0.46 +/- 0.06; p = 0.009).
Conclusions:
At least one mismatch region must be present for there to be a postoperative functional benefit. When a low left ventricular ejection fraction is associated with mismatch, early recovery is substantial.