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Positron Emission Tomography for Assessment of Myocardial Perfusion and Viability
1Wayne State University School of Medicine, Detroit, Michigan.
Insights
Positron emission tomography (PET) can identify viable heart muscle in patients with ischemic cardiomyopathy. Identifying viable myocardium with PET helps predict which patients will benefit from revascularization, improving heart function and survival.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Left ventricular (LV) dysfunction in ischemic cardiomyopathy stems from either scar tissue or viable myocardium.
- Revascularization can significantly improve LV function in patients with viable myocardium.
Purpose of the Study:
- To evaluate the role of Positron Emission Tomography (PET) in differentiating myocardial scar from viable myocardium.
- To assess the predictive value of PET findings for functional recovery after revascularization in patients with ischemic cardiomyopathy.
Main Methods:
- Utilized Positron Emission Tomography (PET) to assess myocardial viability.
- Defined "PET mismatch" (reduced blood flow with increased glucose uptake) as viable myocardium.
- Defined "PET match" (reduced blood flow with reduced glucose uptake) as myocardial scar.
Main Results:
- PET mismatch showed a 79% positive predictive value for improved function post-revascularization.
- PET match demonstrated an 84% negative predictive value for lack of functional recovery.
- A higher number of viable segments on PET correlated with greater functional improvement and survival benefits.
Conclusions:
- Noninvasive assessment of myocardial viability using PET is crucial for managing heart failure due to coronary artery disease.
- PET imaging aids in selecting patients likely to benefit from revascularization, improving quality and quantity of life.
Abstract:
The distinction between left ventricular (LV) dysfunction caused by fibrosis and that arising from viable (hibernating and/or stunned) myocardium has important implications for the management of patients with ischemic cardiomyopathy. In many of these patients, LV function can improve significantly, and even normalize, after revascularization. Positron emission tomography (PET) is the most accurate noninvasive imaging technique for detection of viable myocardium. Increased glucose uptake in dysfunctional segments with reduced blood flow at rest (PET mismatch) indicates the presence of viable myocardium, whereas a concordant reduction in blood flow and glucose uptake (PET match) indicates a myocardial scar. A PET mismatch pattern has a 79% average positive predictive value for predicting improved function after revascularization, whereas a PET match pattern has an 84% average negative predictive value for lack of such functional recovery. The greater the number of viable myocardial segments shown by PET, the greater the probability that revascularization will improve regional and global LV function and, consequently, improve heart failure symptoms and survival. In patients with PET mismatch, long-term survival is consistently poor with medical therapy but significantly improved by early referral to revascularization. This survival benefit is apparent in patients with and without angina. Conversely, long-term survival in patients without such PET mismatch is similar with medical therapy or revascularization, especially if minimal or no anginal symptoms are present. These observations suggest that noninvasive investigation of the amount of viable myocardium should be an important component of the diagnostic evaluation of patients with heart failure because of coronary artery disease. This approach will likely enhance the often difficult process of selecting patients with poor cardiac function in whom revascularization will likely improve both the quality and quantity of life.