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Correlation of functional recovery with myocardial blood flow, glucose uptake, and morphologic features in patients
C Depré1, J L Vanoverschelde, B Gerber
1Division of Cardiology, University of Louvain Medical School, Brussels, Belgium.
Insights
Preoperative myocardial blood flow and glucose uptake predict recovery of heart function after bypass surgery. Less fibrosis and more viable heart cells in dysfunctional areas indicate better outcomes for coronary artery disease patients.
Area of Science:
- Cardiology
- Nuclear Medicine
- Cardiovascular Surgery
Background:
- Coronary artery disease (CAD) often leads to left ventricular dysfunction.
- Assessing myocardial viability is crucial for predicting functional recovery after revascularization.
Purpose of the Study:
- To investigate how preoperative myocardial ultrastructure and metabolism influence contractile function recovery after coronary artery bypass grafting (CABG).
- To determine if noninvasive imaging can predict functional outcomes in patients with CAD and left ventricular dysfunction.
Main Methods:
- Dynamic positron emission tomography (PET) with 13N-ammonia and 18F-deoxyglucose assessed myocardial perfusion and glucose uptake in 53 patients.
- Transmural biopsy specimens analyzed fibrosis and cardiomyocyte alterations.
- Left ventricular function recovery assessed via ventriculography or echocardiography 6 months post-CABG.
Main Results:
- 34 patients showed improved left ventricular function post-CABG; 19 had persistent dysfunction.
- Improved function correlated with higher preoperative myocardial blood flow and glucose uptake.
- Less fibrosis and more altered cardiomyocytes were observed in the dysfunctional myocardium of patients with improved function.
Conclusions:
- Preoperative myocardial blood flow, glucose uptake, fibrosis, and cardiomyocyte status predict functional recovery after CABG in CAD patients.
- Noninvasive metabolic imaging is valuable for identifying viable myocardium and predicting post-revascularization outcomes.
Objective:
Our objective was to investigate the influence of preoperative myocardial ultrastructure and metabolism on recovery of contractile function after coronary artery bypass grafting in patients with coronary artery disease and left ventricular dysfunction.
Methods:
Dynamic positron emission tomography with 13N-ammonia and 18F-deoxyglucose was used to assess myocardial perfusion and glucose uptake in 53 patients scheduled for coronary revascularization because of coronary artery disease and left ventricular dysfunction. The degree of tissue fibrosis and the presence of potentially reversible alterations of cardiomyocytes (loss of myofilaments and accumulation of glycogen) were quantified from transmural biopsy specimens. These were harvested from the center of the dysfunctional area during the operation and analyzed with a light microscope. The recovery of contractile performance was assessed from the changes in left ventricular function at contrast ventriculography or echocardiography before and 6 months after the operation.
Results:
According to postoperative changes in regional wall motion, left ventricular function was considered to have improved in 34 patients, whereas dysfunction persisted in 19 patients. In patients with improved wall motion, ejection fraction rose by 12% and end-systolic volume decreased by 28%. By contrast, in patients with persistent dysfunction, ejection fraction decreased by 6% and end-systolic volume increased by 25%. Before revascularization, myocardium with reversible dysfunction displayed higher levels of absolute myocardial blood flow, higher myocardial glucose uptake, less tissue fibrosis, and more altered cardiomyocytes than myocardium with persistent dysfunction. Significant correlations were found between regional blood flow and the surface of the biopsy specimen covered by fibrosis, as well as between glucose uptake and the density of altered cardiomyocytes.
Conclusion:
In patients with left ventricular ischemic dysfunction, the recovery of regional and global left ventricular function after surgical revascularization is associated with higher preoperative blood flow and glucose uptake, with less tissue fibrosis and a higher amount of viable cardiomyocytes in the dysfunctional area. The current study thus confirms the value of noninvasive preoperative metabolic imaging for identification of residual viable myocardium and for prediction of the functional outcome after revascularization.