For a better assessment of ischemic heart diseases, myocardial viability should be quantified. Current studies underline the importance and the evolution of several techniques and methods used in the evaluation of myocardial viability. Taking into account these considerations, the aim of this manuscript was to present the recent points of view regarding myocardial viability and its clinical significance in patients with ischemic cardiomyopathies and left ventricular dysfunction. On the other hand, the manuscript points out the role of magnetic resonance imaging (MRI), one of the most useful noninvasive imaging techniques, in the assessment of myocardial viability. By comparing the advantages and disadvantages of cardiac MRI, its usefulness can be better appreciated by the clinician. In the following years, it is considered that MRI will be an indispensable imaging tool in the assessment of ischemic heart disease, guiding interventions for revascularization and long-term risk stratification in patients with stable angina or myocardial infarction.