Around 80 to 90 percent of people who experience their first heart attack do survive the heart attack and go on to live a normal and healthy life afterwards.
The younger you are when you have a heart attack the more chance you have of surviving it and the sooner you get medical attention the better chance you have at surviving the heart attack.
If you do have a heart attack and survive you need to make lifestyle changes and eat healthier, get plenty of exercise etc.
When you think you're about to have a heart attack you need to seek medical attention as in calling 911 right away so that medical services can be on their way.
It's better to have the medical services and ambulance when you don't need it then have a heart attack and actually need them.