My setup sounds similar to DocB's.
At my shop, all EKGs are handed to a doc for a sign-off within minutes. We no-likey, they come back ASAP if they've been in triage; if they came in via EMS, they are seen right away.
We get "Code STEMIs" from EMS. We actually use "ACS" as our in-house nickname. As in, if I decide I don't like what I'm seeing, I page the "ACS cardiologist on call" as well as the cath team. Cards generally calls back quickly, we give the story. If it's iffy we'll fax the EKG to cards, but often they'll just ask if we think it's the read deal. If so, it's usually heparin and away they go. (Our cards guys like to reserve plavix as they are doing some studies at the moment, so ntg, asa, heparin, 2 lines if possible, CXR and pacer pads are what we do.)
I caught a dissection masquerating as a posterior MI a couple of months ago, and got him on the scanner table before the (rather-pissed-that-said-pt-wasn't-on-the-cath-table-already) cardiologist showed up. There were a tense couple of minutes there...