stoic said:
so i'm curious what percantage of your patients who are unlikely to have cardiac etiology get the second set of enzymes drawn? this isn't something i've run into out here in the boonies; you've got to look like a cardiac player to get the second set if the first (and ekg) are negative.
and how much of that depends your ability to find evidence for a non-cardiac pathology? does it go back to those who commonly have atypical presentations of cardiac problems (older women, DM, etc)?
In the Meador/Slovis book "A Little Book of Emergency Medicine Rules", one rule is "atypical chest pain IS typical chest pain". As I said above, things not looked for are rarely found.
Another rule is you can't get too many EKGs on a cards player. Since MI (or dissection) is the worst-case scenario (PE that massive would not be so vague), you have to consider it, and, as you will learn with more clinical experience, the first set of markers is a point in space - you need at least a second (if the first is negative) set to compare, to draw a line between them.
Four groups will ALWAYS screw you - ALWAYS - the very young, the very old, the very drunk, and the very crazy. You'll do a more-thorough workup on these folks, lest ye get burned.
An acceptable miss rate for MI (or ectopic) is 0%, but man - and machine - will miss between 2% and 6% - now think about that - anywhere from one in 50 to one patient in 16. Then again, if you are judicious and sober and logical in your thinking, you could be that doc that is the "reasonable man".
A lot of it is (ugh - I hesitate to use the word - so OVERused) 'gestalt'. Some patients will, at first exam, be negative, but something about them clicks in your mind to go a little further. Your gut will help you. It's a lot easier to admit a patient than to send them home. As the old folks in EM will tell you, sending home a chest painer is doing a stress test on yourself.
Here is an abstract from the May Annals of EM showing that outpatient stress tests - up to 3 days - can be done on patients with negative markers and EKGs. What is not clear is how long after (if 3 days is optimal, or you can go longer) you have to do the provocative testing.