Assessment of subendocardial function with myocardial contrast echocardiography.

The classical ischemic cascade anticipates perfusion disturbances to precede the development of wall motion abnormalities, but does not account for regional heterogeneity of both perfusion and function. In this issue of JACC: Cardiovascular Imaging, Xie et al. (1) examine the impact of subendocardial ischemia (identified using real-time myocardial contrast echocardiography [MCE]) on myocardial thickening during dobutamine stress echocardiography (DSE). The subendocardium is the crucible of myocardial dysfunction in many diseases. This part of the myocardium is furthest from the epicardial coronary vessels, compressed by the intracavitary pressure as well as the remainder of the myocardium, and characterized by different myocardial fiber orientation (and therefore contraction