MI=Mycardial Infarction = Heart Attack
AWMI=Anterior Wall MI
IWMI=Inferior Wall MI
The Wall refers to the area on the Left Ventricle which has been infarcted. You can tell by looking at a 12 Lead EKG where the infarct is located. Sometimes you can tell by symptoms, but not always reliable. Ex. AWMI is usually the classic "elephant sitting on my chest" crushing pain. IWMI may present with the indigestion nausea vommiting epigastric pain, if any pain.
It is also important to know this b/c the area infarcted is fed by a specific coronary artery, so for IWMI, it is fed by the RCA or Right Coronary artery, and you can expect more arrhythmias that involve the SA and AV nodes, since this part of the conduction system is also fed by that artery. So if you saw a second degree heart block in an IWMI, you may realize it can be more serious than a second degree heart block in a Lateral wall MI, for example. Naturally all arrhythmias must be monitored closely, but knowing where the infarct is may be an indication that a pacemaker is needed sooner rather than later, or a means of anticipating certaim complications.
You probably know most of this already, but not what the abbreviation was, I just give it in case anyone who doesn't know is reading also.