Assessment of no-reflow regions using cardiac MRI

Ischemic myocardial injury can be broadly characterized as either reversible or irreversible. Within irreversibly injured (infarcted) regions microvascular perfusion can vary from nearly normal to nearly zero, even in the presence of an open infarct-related artery ('no-reflow'). Historically, non-invasive assessment of heterogeneous microvascular perfusion within myocardial infarcts has been problematic. More recently, however, contrast-enhanced MRI has emerged as a promising approach to the examination of these regions in patients with myocardial infarction. In this review we highlight a number of important animal and human studies of no-reflow regions examined using contrastenhanced MRI. These studies provide evidence that contrast- enhanced MRI can accurately characterize the presence and spatial extent of no-reflow regions, discriminate between areas of necrosis with and without no-reflow, and provide clinically meaningful predictive information regarding left ventricular remodeling and patient outcome.