<unk><unk>  is commonly thought of as a sign of Left Main Coronary Artery (LMCA) occlusion.  However, STE 0.5mm or greater in lead<unk>  to be present in 78% of patients with and 14% of patients without LMCA stenosis.
Use > 1mm and the clinical status of a patient if activating the cath lab based on<unk>  and concern for a STEMI
AVR ST elevation
Cardiac
T wave changes
ST-segment elevation myocardial infarction 
ST segment depression
Post-MI 
De Winter's T waves
Previous MI with recurrent ischemia in same area