Myocardial Viability Imaging

The concept of hibernating myocardium originated from observations in the 1970s that the myocardial dysfunction seen in patients with chronic coronary artery disease (CAD) was not always permanent (1). The fact that revascularization with coronary artery bypass grafting (CABG) could result in the recovery of contractile function in previously akinetic segments led to the development of numerous imaging techniques to differentiate viable from nonviable myocardium. Although enhanced regional and global left ventricular (LV) function can be demonstrated and often translates into symptomatic benefit in patients with severe ischemic LV dysfunction, the impact on survival of identifying and then revascularizing viable but dysfunctional myocardium remains unclear. Previous outcome studies using various imaging modalities to assess viability were small and retrospective in nature, and predated the era of modern medical therapy (2,3). Only recently have 2 prospective, randomized trials comparing medical therapy to surgical or percutaneous revascularization based on preintervention viability testing been completed and reported,