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Correlation between extent of myocardial dysfunction and markers of irreversible damage in failing hearts
R De Maria1, L Ruffini, R Testa
1C.N.R. Clinical Physiology Institute, Section of Milan, Niguarda Hospital, Italy.
Insights
Thallium-201 (201Tl) rest-redistribution imaging shows good sensitivity for detecting viable heart muscle but limited specificity. However, identifying over nine viable segments accurately predicts minimal left ventricular fibrosis in individual patients.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- The relationship between 201Tl uptake and structural changes in advanced postischemic pump dysfunction is not well understood.
- Existing experimental models do not fully represent the complex mix of normal, viable, and necrotic heart tissue seen in chronic ischemic heart disease.
Purpose of the Study:
- To correlate 201Tl uptake patterns with histologic findings in patients undergoing heart transplantation.
- To evaluate the diagnostic accuracy of 201Tl rest-redistribution imaging in assessing myocardial viability.
Main Methods:
- Four-hour redistribution 201Tl SPECT was performed on heart transplant candidates.
- Delayed 201Tl uptake was categorized and compared with echocardiographic wall motion and excised heart histology.
Main Results:
- In ischemic heart disease, 201Tl uptake was inversely correlated with myocardial fibrosis (r = -0.50).
- Severe 201Tl defects (<50%) predicted extensive fibrosis (>30%) with 83% sensitivity and 63% specificity.
- Identifying more than nine viable segments predicted <15% left ventricular fibrosis with 86% accuracy.
Conclusions:
- 201Tl rest-redistribution imaging demonstrates high sensitivity but limited specificity for viable myocardium assessment.
- In individual patients, the number of viable segments identified by imaging reliably predicts the extent of myocardial fibrosis.
Background:
The structural correlates of 201Tl uptake in patients with advanced postischemic pump dysfunction are unclear. There are no good experimental models adequately reflecting the mixture of normal, dysfunctional but viable, and necrotic regions characteristic of chronic ischemic heart disease in human beings.
Methods And Results:
Four heart transplant candidates with idiopathic dilated cardiomyopathy and seven with ischemic heart disease underwent rest-injection 4-hour redistribution 201Tl single-photon emission computed tomography before surgery. Delayed tracer uptake was categorized into severely reduced (<50%), mildly or moderately reduced (50% to 74%), and normal (> or =75%) and related to echocardiographic wall motion and histologic findings in the hearts excised at transplantation. In idiopathic dilated cardiomyopathy, despite severe wall motion impairment, minimal or mild myocardial damage and homogeneously high 201Tl uptake were found. In ischemic heart disease, wall motion did not discriminate extensive from mild structural damage. 201Tl activity was inversely related to myocardial fibrosis (r = -0.50, p = 0.0001). Severe defects in 201Tl uptake (<50%) predicted extensive (>30%) fibrosis with 83% sensitivity and 63% specificity. Segmental akinesis and apical location resulted in loss of sensitivity (74% and 58%, respectively). No histologic or wall motion abnormality accounted for poor specificity. In the individual patient, more than nine segments determined viable by imaging criteria predicted left ventricular fibrosis of less than 15% with 86% accuracy.
Conclusions:
This histopathologic-clinical correlative study supports current evidence of good sensitivity but limited specificity of 201Tl rest-redistribution tomographic imaging in the evaluation of viable myocardium. In the individual patient, more than nine viable segments reliably predicted a limited extension of fibrosis.