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Quantitative relation between myocardial viability and improvement in heart failure symptoms after revascularization
M F Di Carli1, F Asgarzadie, H R Schelbert
1Department of Medical and Molecular Pharmacology, University of California at Los Angeles, School of Medicine, USA.
Insights
Preoperative positron emission tomography (PET) imaging can identify patients with ischemic cardiomyopathy who will benefit most from coronary artery bypass surgery (CABG). A larger myocardial viability extent, indicated by a perfusion-metabolism mismatch, predicts greater improvement in heart failure symptoms post-CABG.
Area of Science:
- Cardiology
- Nuclear Medicine
- Cardiac Surgery
Background:
- Preoperative assessment of myocardial viability is crucial for identifying patients with coronary artery disease and left ventricular dysfunction who may benefit from revascularization.
- While the clinical utility of myocardial viability quantification is known, the direct relationship between preoperative viability extent and changes in heart failure symptoms post-coronary artery bypass surgery (CABG) requires further documentation.
Purpose of the Study:
- To investigate the correlation between the extent of myocardial viability, assessed via preoperative positron emission tomography (PET), and the degree of improvement in heart failure symptoms following CABG.
Main Methods:
- 36 patients with ischemic cardiomyopathy underwent CABG and preoperative PET imaging using 13N ammonia and fluorine-18-deoxyglucose to quantify myocardial viability and perfusion defects.
- Functional status was evaluated using a Specific Activity Scale before and after CABG.
- Quantitative analysis of PET images assessed the extent and severity of perfusion abnormalities and myocardial viability (flow-metabolism mismatch).
Main Results:
- A significant linear correlation (r = .87, P < .0001) was observed between the total extent of PET mismatch and the percentage improvement in functional status post-CABG.
- A perfusion-metabolism mismatch of 18% or greater demonstrated 76% sensitivity and 78% specificity in predicting functional status improvement.
- Patients with large mismatches (≥18%) experienced a 107% improvement in functional status, compared to a 34% improvement in those with minimal or no mismatch (<5%).
Conclusions:
- The magnitude of heart failure symptom improvement after CABG in patients with ischemic cardiomyopathy is directly related to the preoperative extent of myocardial viability.
- Positron emission tomography (PET) imaging is effective in assessing myocardial viability and predicting clinical benefit from CABG.
- Patients exhibiting significant perfusion-metabolism mismatches on PET imaging are most likely to achieve substantial clinical improvement after revascularization surgery.
Background:
Studies of patients with coronary artery disease and left ventricular dysfunction have shown that preoperative quantification of myocardial viability may be clinically useful to identify those patients who will benefit most from revascularization both functionally and prognostically. However, the relation between preoperative extent of viability and change in heart failure symptoms has not been documented carefully. We assessed the relation between the magnitude of improvement in heart failure symptoms after coronary artery bypass surgery (CABG) and the extent of myocardial viability as assessed by use of quantitative analysis of preoperative positron emission tomography (PET) images.
Methods And Results:
We studied 36 patients with ischemic cardiomyopathy (mean left ventricular ejection fraction, 28 +/- 6%) undergoing CABG. Preoperative extent and severity of perfusion abnormalities and myocardial viability (flow-metabolism mismatch) were assessed by use of quantitative analysis of PET images with 13N ammonia and fluorine-18-deoxyglucose. Each patient's functional status was determined before and after CABG by use of a Specific Activity Scale. Mean perfusion defect size and severity were 63 +/- 13% and 33 +/- 12%, respectively. Total extent of a PET mismatch correlated linearly and significantly with percent improvement in functional status after CABG (r = .87, P < .0001). A blood flow-metabolism mismatch > or = 18% was associated with a sensitivity of 76% and a specificity of 78% for predicting a change in functional status after revascularization. Patients with large mismatches (> or = 18%) achieved a significantly higher functional status compared with those with minimal or no PET mismatch (< 5%) (5.7 +/- 0.8 versus 4.9 +/- 0.7 metabolic equivalents, P = .009). This resulted in an improvement of 107% in patients with large mismatches compared with only 34% in patients with minimal or no PET mismatch.
Conclusions:
In patients with ischemic cardiomyopathy, the magnitude of improvement in heart failure symptoms after CABG is related to the preoperative extent and magnitude of myocardial viability as assessed by use of PET imaging. Patients with large perfusion-metabolism mismatches exhibit the greatest clinical benefit after CABG.