Could the damage done to heart in a heart attack be reversed and normality restored to a human heart?

Not all: During heart attack, there is death of tissues or heart muscles. They don't regenerate. There would be areas which are still alive and when oxygenation to those areas are improved by improved blood flow, they can recover to be normal again. When there is no death of muscles yet, it is only angina or angina equivalent (if no pain) and that can recover with reperfusion.