Mike626, and the AHA, are absolutely correct that coughing is NOT a valid medical procedure. However, I have seen it save two people's lives (paramedics actually).

First, let's discuss what a heart attack is. A Myocardial Infarction (MI) occurs when a clot somewhere cuts off blood supply to the heart. Because the heart is a muscle, it depends on the blood supply to keep it alive. There are also other forms, as mentioned above, such as arrythemia, tachycardia, etc, where either your heart is beating too fast, too slow, not consistantly, or is firing incorrectly. These differences all show up in a normal EKG:

A (very badly ASCII drawn) normal EKG:

         /  \
    -\  /    \
---/  -/      \  --------------

If it looks anything other than that, there is something wrong with your heart. Remember that the heart beating is nothing but a set of electrical impulses, so if something blocks those it a) won't work as efficiently and b) will show up in an EKG.

So what can you do if you are alone? To start, at the VERY FIRST SIGN of chest pains, or chest pressure, call 911. That is what we are here for! I would rather come out to your house at 3am, slap on an EKG, and show you that you are just having heartburn, then come at 7am when your wife (or husband) can't wake you up because your heart stopped about 5:30am.

Second, take aspirin. This only works if you have not been taking ibuprofen. Ibuprofen actually reduces the effect of aspirin, blocking between 90 - 98% of its effectiveness. Aspirin is a blood thinner, so if you do have a clot, it may actually reduce the clot. If you have been prescribed Nitroglycerin, nows the time to take it as well. If the pain doesn't go away after three sprays, and you haven't called 911, do that now.

Third, find someone. Call a neighbor. Go outside. Do something that gets you near someone, in case you do collapse. Hopefully this person knows CPR, so that you might be able to be helped. But from the moment your heart stops, We have probably about 10 minutes (if CPR is in progress) to get there and administer medicine. No boys and girls, CPR does not bring people back. All it does is keep some blood circulating (at about 10-15% of the normal circulation) until we can get there and shock them, or administer drugs, or both.

Finally, relax as much as possible. Don't get upset, try to breathe normally, and stay calm. If your wife/husband/family member is not calm, tell them to get out. That is the last thing you need.

And about the coughing thing? The reason that works (though is not recommended) is because it can actually convert an abnormal rhythm to a normal sinus rhythm. It is similar to the fist in the chest that you sometimes see nurses do in older movies. But it only works if you catch it early, are having the type of attack where your rhythm is abnormal, and is a rhythm that, when converted, goes to a normal rhythm, and doesn't just stop all together.

So: 1) Call 911, 2) Take Aspirin, 3)Get someone and 4) Relax. It might just save your life.

khym chanur gives a good link to the origins of a "not-so-helpful" email about this very topic: http://www.snopes2.com/toxins/coughcpr.htm