Some people who have a heart attack
are dead by the time they hit the floor, not all attacks are fatal and some people have many during their lifetime.
If you suspect you are having one and you have company, get them to call an ambulance and lie down on the floor and relax as much as is possible, if possible give the person with you details of what to do should you lose consciousness, loosening tight clothing, making sure your airway is clear, artificial respiration
and cardiac massage
If you are alone try to get to the telephone and do then do the same, don't forget to leave your address, tracing a call can waste valuable time.