Are you sure it is 15? That sounds awfully low. A normal ejection fraction is around 55-70%. Below 30% is severely abnormal, so 15 sounds extreme and your cardiologist should be giving you advice and major treatment. As for exercise improving the fraction, I would think that would depend on the condition of your heart after the heart attack. My husband had a heart attack in his 40's in a major artery but fortunately (if there is such a thing) it was low in the heart area near the apex and while he has permanent damage, he had an ejection fraction of about 38-40% after his angioplasty. As a nurse, I was very concerned about him being limited in his activities for the future as a relatively young man. One cardiologist told him to go home and "take it easy." To me this was not a very helpful response; his medical cardiologist told him to improve his condition by taking it slowly but methodically. "Start exercising by walking out one or two minutes from the house, and then back. The next day do three minutes and back. Continue adding time as you tolerate it. Guess what, he is now 80 years old, rides a bike, has hiked to the bottom of the Grand Canyon with me twice and does all his own lawn work and car maintenance. I don't know what to tell you except to keep moving--everyone can move something as Richard Simmons used to say. I wish you the best of care and well-being.