From source:
http://www.nlm.nih.gov/medlineplus/ency ... 000063.htmFirst Aid
If you think someone is having a heart attack:
Have the person sit down, rest, and try to keep calm.
Loosen any tight clothing.
Ask if the person takes any chest pain medication, such as nitroglycerin, for a known heart condition, and help them take it.
If the pain does not go away promptly with rest or within 3 minutes of taking nitroglycerin, call for emergency medical help.
If the person is unconscious and unresponsive, call 911 (or your local emergency number), then begin CPR.
If an infant or child is unconscious and unresponsive, perform 1 minute of CPR, then call 911.
DO NOT
Do NOT leave the person alone except to call for help, if necessary.
Do NOT allow the person to deny the symptoms and convince you not to call for emergency help.
Do NOT wait to see if the symptoms go away.
Do NOT give the person anything by mouth unless a heart medication (such as nitroglycerin) has been prescribed.