Not sure where, but I'm sure you can find them with some research.
I have read a few articles in the past, out of nursing and medical journals.
In a nutshell this is it:
Currently the standard is to use Troponin-I. This is an enzyme that is also specific to the heart, just like the CPK-MB enzyme. There are actually 3 m/b four types of Troponin. However, the other types are either very dificult to measure the levels, or inaccurate. Our hospital uses myoglobins with Troponins. I'm sure you are aware that myoglobin is not specific, but a general enzyme found in the heart, and all skeletal muscle. The reason for the use of the two together are this: If a pt comes in with chest pain for an hour, they run them both. Why? Because myoglobin will rise, when the heart is damaged within 1 -2 hours. If it is up, they will wait two more hours, and run a Tropnin again, to recheck it's level. Why? Because Troponin-I levels do not rise, until 2- 4 hours after myocardial ischemia or infarction. The one thing to remember, is that any rise of the myoglobin m/b consindered insignificant if the pt: #1 Has fallen recently, #2 has renal disease or damage, #3 recent electracution or similar. These three things can all cause the myglobin to rise also. So the myoglobin is not always helpfull. One last bit of info, is that Troponin is found in the kidneys, and have been reported to cause an increased level of troponin in severely diseased, or renal traumatized patients. Although, we have not seen it in three years.
Being that Troponin rises much faster than some of the traditional cardiac markers and enzymes, that seems to be the trend in early ID of AMI's. The normal level is <.4, or <1.1, depending on which standard of measurement your lab uses.