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[Identification of viable myocardium in patients with chronic ischemic disease and left ventricular dysfunction:
P Perrone Filardi1, S L Bacharach, R O Bonow
1Divisione di Cardiologia, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD.
Insights
Viable myocardium in severely dysfunctional hearts can be identified using advanced imaging. Positron emission tomography (PET) and single photon emission computed tomography (SPECT) reveal tissue viability in akinetic or dyskinetic regions.
Area of Science:
- Cardiovascular Imaging
- Nuclear Cardiology
- Myocardial Viability Assessment
Background:
- Severe left ventricular dysfunction in chronic coronary artery disease often presents with akinetic or dyskinetic myocardial regions.
- Determining the presence of viable myocardium in these dysfunctional areas is crucial for guiding therapeutic strategies.
Purpose of the Study:
- To assess the presence of viable myocardium in regions with severe systolic dysfunction using combined imaging techniques.
- To correlate regional wall motion abnormalities with myocardial blood flow and glucose metabolism.
Main Methods:
- 22 patients with coronary artery disease and left ventricular dysfunction underwent thallium-201 SPECT, H2(15)O and 18-fluorodeoxyglucose (FDG) PET, and MRI.
- Myocardial regions were categorized as akinetic-dyskinetic, hypokinetic, or normal based on MRI-derived wall thickening.
- Regional myocardial blood flow and FDG uptake were assessed using PET, and thallium uptake by SPECT.
Main Results:
- Out of 60 akinetic or dyskinetic regions, 47 (78%) demonstrated evidence of viable myocardium.
- SPECT showed reversible thallium defects in 37 regions, with 34 also exhibiting FDG uptake.
- Even in regions with irreversible thallium defects, 7 out of 20 showed metabolic activity via FDG uptake.
Conclusions:
- A significant proportion of akinetic or dyskinetic myocardial regions in patients with severe left ventricular dysfunction exhibit viable tissue.
- Combined SPECT and PET imaging can effectively identify myocardial viability, aiding in treatment decisions for coronary artery disease.
Abstract:
To identify the presence of viable myocardium in areas of severe systolic dysfunction, we studied 22 patients (age 45 to 78 years) with chronic coronary artery disease and left ventricular dysfunction (mean ejection fraction 29 +/- 9%). All subjects underwent thallium-201 single photon emission computed tomography (SPECT), using the reinjection technique, positron emission tomography (PET) with H2(15)O and 18-fluorodeoxyglucose (FDG) to measure regional blood flow and exogenous glucose uptake, respectively, and nuclear magnetic resonance imaging (MRI). From matched transaxial PET, SPECT and MRI tomograms, a total of 290 left ventricular myocardial regions were analyzed. According to the regional wall thickening, measured from MRI, 3 groups of myocardial regions were identified: akinetic-dyskinetic (n = 60), showing either absence of systolic thickening or systolic thinning; hypokinetic (n = 97), showing an absolute wall thickening less than or equal to 2 mm; normal (n = 133), showing an absolute wall thickening greater than 2 mm. Of the 60 akinetic or dyskinetic regions, 3 were normal by SPECT and 37 corresponded to either a total or partially reversible thallium defect: 34 of these 40 regions also showed presence of FDG uptake by PET. The remaining 20 akinetic or dyskinetic regions showed a thallium defect that remained irreversible after reinjection: in 7 of these 20 regions, however, there was evidence of metabolic activity, as expressed by FDG uptake. Thus, 47 (78%) of the myocardial akinetic or dyskinetic regions showed presence of viable tissue.(ABSTRACT TRUNCATED AT 250 WORDS)