Related Experiment Videos
Agreement and disagreement between "metabolic viability" and "contractile reserve" in akinetic myocardium
J H Cornel1, J J Bax, A Elhendy
1Department of Cardiology, Medical Center Alkmaar, The Netherlands.
Insights
Assessing myocardial viability in chronic coronary artery disease is crucial. Dobutamine echocardiography shows good agreement with SPECT imaging but may underestimate viability compared to F18-fluorodeoxyglucose imaging.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Assessing myocardial viability in akinetic segments of patients with chronic coronary artery disease and reduced left ventricular function is critical for treatment decisions.
- Viability is characterized by intact perfusion, preserved metabolism, and contractile reserve, though these may not all be present simultaneously.
- Contractile reserve is often less preserved than metabolic activity or perfusion in viable myocardium.
Purpose of the Study:
- To directly compare perfusion imaging (thallium-201 SPECT), metabolic imaging (F18-fluorodeoxyglucose SPECT), and contractile reserve assessment (low-dose dobutamine echocardiography) in akinetic myocardium.
- To evaluate the agreement between these imaging modalities in identifying viable myocardial segments.
Main Methods:
- Studied 40 patients with chronic coronary artery disease and depressed left ventricular function (mean ejection fraction 31%).
- Utilized thallium-201 SPECT for perfusion, F18-fluorodeoxyglucose SPECT for metabolism, and low-dose dobutamine echocardiography for contractile reserve assessment.
- Analyzed akinetic myocardial segments identified by resting echocardiography.
Main Results:
- Of 165 akinetic segments, 154 showed hypoperfusion. F18-fluorodeoxyglucose imaging revealed perfusion-metabolism mismatches in 41 segments.
- Contractile reserve was present in 80% of segments with a perfusion-metabolism mismatch versus 6% with a match (P < .0005).
- Agreement between SPECT and dobutamine echocardiography was 87%; however, dobutamine echocardiography underestimated viability in 27% of segments identified as viable by SPECT.
Conclusions:
- SPECT and dobutamine echocardiography demonstrate good agreement for assessing myocardial viability.
- A significant number of viable segments on SPECT do not exhibit contractile reserve, suggesting dobutamine echocardiography may underestimate viability compared to F18-fluorodeoxyglucose imaging.
Background:
In patients with chronic coronary artery disease and depressed left ventricular function, assessment of residual viability in akinetic myocardium is important for therapeutic management. Intact perfusion, preserved metabolism, and presence of contractile reserve are different aspects of cellular viability. However, not all viable cells exhibit all characteristics; it is thought that contractile reserve is less often preserved compared with metabolic activity or intact perfusion. In this study we performed a direct comparison between perfusion imaging with thallium-201 single photon emission computed tomography (SPECT), metabolic imaging with F18-fluorodeoxyglucose SPECT, and assessment of contractile reserve with low-dose dobutamine echocardiography in akinetic myocardium.
Methods And Results:
Forty patients with depressed left ventricular function (mean left ventricular ejection fraction 31% +/- 16%) were studied. Resting echocardiography showed akinesis in 165 (32%) segments. Most (n = 154, 93%) of these segments demonstrated resting hypoperfusion. F18-fluorodeoxyglucose imaging revealed a perfusion-metabolism mismatch in 41 segments and a match in 113 segments. Contractile reserve was present in 33 (80%) of the segments with a perfusion-metabolism mismatch and in 7 (6%) segments with a match (P < .0005). Of the 11 segments with normal perfusion, only 5 (45%) showed contractile reserve. The agreement between SPECT and dobutamine echocardiography was 87%. Although 94% of the segments that were nonviable on scintigraphy did not show contractile reserve, the disagreement between SPECT and dobutamine echocardiography was caused mainly by the absence of contractile reserve in 27% of the segments that were viable on scintigraphy.
Conclusion:
This study shows a good agreement between SPECT and dobutamine echocardiography, although a substantial number of segments with preserved viability on SPECT do not exhibit contractile reserve, indicating underestimation of viability by dobutamine echocardiography compared with F18-fluorodeoxyglucose imaging.