If we find someone who may be suffering heart attack, the first thing to do is ask someone to call the emergency medical service or we must do it ourselves if he is alone. Then we must begin first aid.
If it is possible try to ensure that the affected person takes a seat and try to be as calm as possible. We must also consult him if he has any medicine that his doctor has prescribed for chest pain (such as nitroglycerin) and help him to take it. If he has very tight clothes should loosen it.