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The clinical relevance of myocardial viability in patient management
J Lemlek1, J Heo, A S Iskandrian
1Philadelphia Heart Institute, Presbyterian Medical Center, PA 19104.
Insights
Myocardial viability is crucial in coronary artery disease (CAD). Thallium imaging alone suggests viability in 21% of patients, but this figure drops to 12% when considering ventriculography data.
Area of Science:
- Cardiology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Assessing myocardial viability is critical for guiding treatment decisions in patients with coronary artery disease (CAD).
- Exercise single-photon emission computed tomography (SPECT) thallium imaging is a standard technique for evaluating myocardial perfusion and viability.
- Differentiating between ischemic and infarcted (scar) tissue is essential for patient management.
Purpose of the Study:
- To determine the clinical significance of myocardial viability in patients with angiographically proven CAD.
- To compare the assessment of myocardial viability using thallium imaging alone versus combined with ventriculographic data.
- To inform the necessity of advanced imaging techniques for viability assessment.
Main Methods:
- Exercise SPECT thallium imaging was performed on 532 patients with CAD.
- Conventional 4-hour delayed images were analyzed to distinguish scar from ischemia (20 segments per patient).
- Contrast ventriculography was used to assess wall motion and ejection fraction in a subset of patients.
Main Results:
- 168 patients (31%) had scar tissue, with 114 (21%) having scar alone or more scar than ischemia.
- Thallium imaging alone indicated significant viability in 114 patients (21%).
- When ventriculographic data were included, the significance of viability decreased to 64 patients (12%) (p < 0.001).
Conclusions:
- Myocardial viability is a significant consideration in approximately 21% of CAD patients based on thallium imaging alone.
- Incorporating ventriculographic data reduces the estimated prevalence of significant myocardial viability to 12%.
- These findings highlight the importance of integrating multiple imaging modalities for accurate viability assessment and may influence the use of metabolic imaging and novel scintigraphic techniques.
Abstract:
This study examined the importance of viability as a clinical issue in 532 patients with angiographically proven CAD who underwent exercise SPECT thallium imaging. Conventional 4-hour delayed images were used to differentiate scar tissue from ischemia (20 segments per patient). There were 90 patients (17%) with normal images, 274 patients (52%) with reversible defects only, and 168 patients (31%) with scar tissue either with or without associated ischemia. The patients with scar tissue were subdivided according to the number of segments with fixed defects and the number of additional reversible defects. There were 114 patients with scar tissue alone or more scar tissue than ischemia. Contrast ventriculography in these 114 patients revealed normal wall motion or ejection fraction in 50 patients. On the basis of results of thallium imaging alone, the issue of viability was probably significant in 114 patients (21%); however, when the ventriculographic data were also included, the issue was significant in only 64 patients (12%) (p < 0.001). Thus myocardial viability is an important issue in 21% of patients with CAD when conventional thallium imaging is used, but this percentage decreases to 12% when wall motion and ejection fraction data are also included. These data may be important in considerations for the need of metabolic imaging and emerging scintigraphic techniques.