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[Myocardial viability. Myocardial viability post-infarct: contribution of dobutamine-echography]
Abstract:
ROUTINE EXPLORATION: Echocardiography during dopamine perfusion has been widely proven as an effective tool for determining myocardial viability. Dobutamine has marketing authorization in France for stress-echocardiography and is widely used in clinical practice outside research protocols. The exploration must however be conducted within an appropriately equipped cardiac intensive care unit. Stress-echocardiography has certain advantages over isotropic techniques, in terms of equipment costs, examination time and exposure to isotopes. POST-INFARCTION: Dobutamine-echocardiography enables detection of viable myocardium within the infarct zone, evaluates the degree of residual ischemia in the infarct zone and provides information on prognosis. It would not however be reasonable to perform stress-echocardiography as a first line exploration after infarction. International guidelines recommend a sub-maximal ECG exercise test prior to coronarography. The contribution of stress-echocardiography after infarction is its ability to give precise information on myocardial viability and residual ischemia in one or more territories to compare with coronary lesions, thus allowing indication for revascularization. CHRONIC ISCHEMIC CARDIOPATHY: Dobutamine-echocardiography can be used to detect hibernating myocardium in patients with chronic ischemic cardiopathy. In this indication, the sensitivity of stress-echocardiography is slightly lower than thallium scintigraphy, but its specificity and positive predictive values are higher. The best predictive value is obtained with bimodal dobutamine-echocardiography: improve-med thickening at low doses and a degradation at high dose is predictive of functional improvement after revascularization in 72% of the cases. In more severe cases with ejection fraction < 35%, improvement in hibernating myocardium after revascularization leads to a significant improvement in left ventricular ejection fraction.