What happens, if things go well, is this:
The EMTs transmit a picture of the electrocardiogram to us[1]. We confirm that it's a STEMI (the kind of heart attack where speed matters the most, as opposed to an NSTEMI, which isn't quite as urgent), and alert the catheter lab and the attending cardiologist. Half the ER personnel drops everything else to prepare for the patient's arrival.
The patient arrives. We transfer them to our gurney. One nurse gets the patient's clothes off (with scissors if necessary) while another nurse attaches electrocardiogram electrodes and a third shaves the puncture site for the catheter.
The ER physician puts in an iv line and draws blood while informing the patient of the treatment plan. The cardiologist takes a very quick history of the patient and confirms the STEMI with the second electrocardiogramm. We wheel the patient up to the catheter lab and get started.
Altogether, if everything goes well, it's something like five to twelve minutes from the moment the patient comes through our doors to the moment we've got the patient on the operating table.
[1]By taking a picture of it on their phone and transmitting it via Whatsapp, which is just about the ugliest, hackiest and probably borderline-legal way of transmitting patient data imaginable, but it gets the job done.