A growing number of clinical trials are evaluating the effects of stem cell therapy in patients with chronic ischemic heart dysfunction. As most of the clinical trials included a limited and different number of patients, various stem cell sources and several delivery approaches, results vary substantially between these studies. We analyse whether the assessment of myocardial viability may be important when evaluating effects of stem cell transplantation on parameters of left ventricular remodeling. Viability assessment could help to find the best type of stem cell and the best method of cell delivery to be used in chronic ischemic heart dysfunction.