A method of treating heart failure and improving cardiac function by administering stem cell products to a heart in need of treatment, whereby the stem cell products improve cardiac muscle function thereby treating heart failure and improving cardiac function. A method of enriching or regenerating damaged myocardium by administering stem cell products to damaged myocardium. Stem cell products for use in treating heart failure are also provided. A composition for enriching and regenerating damaged myocardium, the composition having stem cell products in a pharmaceutically acceptable carrier.