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An approach to myocardial viability based on perfusion, function and metabolic substrates
1Department of Medicine, University of Massachusetts Medical Center, Worcester 01655-0243, USA.
Insights
Assessing myocardial viability is crucial for patients with coronary artery disease. Nuclear cardiology imaging, particularly positron emission tomography (PET), helps identify viable heart tissue, guiding revascularization decisions and improving patient outcomes.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Myocardial viability assessment is key in managing coronary artery disease (CAD) and left ventricular dysfunction.
- Down-regulation of contractile function in viable myocardium can be reversed with revascularization.
- Altered cellular metabolism in non-contractile myocardium necessitates evaluation of overall oxidative metabolism.
Purpose of the Study:
- To highlight the importance of assessing myocardial viability in patients with CAD and ventricular dysfunction.
- To discuss the role of nuclear cardiology imaging techniques in evaluating myocardial viability.
- To emphasize the clinical value of tests combining blood flow and ventricular wall motion assessment.
Main Methods:
- Review of nuclear cardiology imaging techniques, including thallium imaging and positron emission tomography (PET).
- Discussion of how these techniques monitor oxidative phosphorylation and predict cardiac tissue viability.
- Emphasis on the diagnostic potential of tests integrating coronary blood flow and left ventricular wall motion.
Main Results:
- Nuclear imaging can monitor oxidative phosphorylation, predicting overall cardiac tissue viability.
- Positron emission tomography (PET) is considered a gold standard for myocardial viability assessment.
- PET data demonstrate clinical impact on patient management, treatment, and prediction of long-term outcomes.
Conclusions:
- Functional evaluation of myocardial viability is essential for patients with CAD and significant left ventricular dysfunction.
- Diagnostic tests combining blood flow and wall motion assessment are valuable for identifying candidates for revascularization.
- Patients should undergo viability testing to explore potential reversibility before being considered for end-stage heart disease.
Abstract:
In the clinical assessment of myocardial viability, the concept of down-regulation of contractile function is important in understanding the interaction between coronary flow and ventricular function. In this state, the myocardium remains viable, although lacking overt contractile function, and may be totally reversible with complete revascularization. This abnormality is also associated with altered cellular metabolism, and individual substrate determinations are not necessarily as predictive of myocardial viability as are evaluations of overall oxidative metabolism. Nuclear cardiology imaging techniques can monitor oxidative phosphorylation and predict the overall viability of cardiac tissue. In addressing the clinical challenge of identifying those patients who would receive the most benefit from coronary revascularization, it is clear that a diagnostic test which combines blood flow and an evaluation of left ventricular wall motion would be of great potential value. One can make a strong case for the use of thallium imaging as an acceptable and readily available method, but the use of positron emission tomography (PET) tracers has been a strong gold standard. Recent work suggests that PET data do have a clinical impact in patient management, treatment, and the prediction of long-term morbidity and mortality. Patients with known coronary artery disease and significant left ventricular dysfunction need a functional evaluation of myocardial viability. Given this type of evaluation, patients should not be condemned to end-stage heart disease without performing at least one test for potential reversibility.