In general, it's best to call 911 if you have any reason to suspect that someone is having a heart attack. Waiting even an hour or two may limit treatment options and reduce the chance of a full recovery. It's common for someone having a heart attack to downplay the situation because he or she is embarrassed and doesn't want to cause a scene. Take charge and call for help even if the person tries to talk you out of it. Don't wait to see if heart attack symptoms go away -- and call even if the symptoms do disappear or come and go. If it turns out to be something less serious than a heart attack, at least you'll have some peace of mind.

Bear in mind that not all of the following warning signs occur in every heart attack.