Methods of Assessment and Clinical Relevance of Myocardial Hibernation and Stunning

During the past decade there has been intense clinical interest in the differentiation between scar tissue and postischemic viable myocardium and its relevance to patient treatment and outcome. Frequently used paradigms of myocardial viability are hibernation and stunning which both refer to reversible left-ventricular contraction impairment. Hibernation describes the concomitant reduction of myocardial perfusion and contractility, whereas stunning characterizes contractile impairment persisting for some time after perfusion has been restored. In the clinical setting ischemia, stunning, hibernation, and necrosis may coexist. A variety of imaging techniques encompassing a wide range of physiologic entities such as contractile function, perfusion, membrane integrity and cell metabolism are currently in use to differentiate between these conditions, and they allow an accurate decision making with respect to revascularization procedures or conservative management. This article reviews current concepts and diagnostic methods to assess viable myocardium, and it attempts to address the clinical relevance of revascularization procedures in patients with coronary artery disease harboring dysfunctional but viable myocardium.