The clinical utility of echocardiography in the assessment of myocardial viability.

Abstract

The detection of reversible myocardial dysfunction may be important in patients with acute and chronic myocardial dysfunction due to coronary artery disease. Assessment for reversible dysfunction may identify high-risk patients who may benefit most from aggressive revascularization therapy. Echocardiography has been used to identify reversible myocardial dysfunction in both subsets of patients. The resting echocardiogram is useful because wall thickening is very predictive of viable myocardium. Chamber size, global ventricular function and wall thickening can be quantified. Inotropic stimulation by catecholamines or the Gregg phenomenon accurately differentiates reversible from fixed dysfunction in animal models of myocardial infarction. Clinically, improved wall thickening during low-dose dobutamine infusion (dobutamine responsive wall motion) may accurately detect reversible dysfunction in both acute and chronic ischemic myocardial dysfunction. The accuracy of dobutamine echocardiography has been compared to resting planar and SPECT 201Tl scintigraphy and PET. Two studies demonstrated that dobutamine responsive wall motion may be as sensitive as resting 201Tl SPECT scintigraphy and PET, respectively, for reversible dysfunction after acute myocardial infarction. Two other small studies (14 patients each) demonstrated that dobutamine- responsive wall motion was as sensitive as resting quantitative 201Tl planar scintigraphy in patients with chronic dysfunction undergoing revascularization.