Another possible factor could be the fact that doctors tend to make more mistakes during operations on Fridays compared to start of week.
STEMI centers (this is picked up by EMS and these ambulances are redirected to appropriate centers) have 24/7 cath lab coverage and any major one will have an ER bypass even during afterhours to expedite care.
In fact more and more hospitals (and all the major ones) announce a “Code STEMI” overhead either when the ambulance is dispatched or as soon as the ECG showing ST elevations is discovered in triage/ER to activate the team and reduce door-to-balloon time.
Honestly, when I have an ICU nurse providing procedural sedation for me I essentially just defer to their expertise on the rhythms and if they're worried I activate the mobile response team.
That matches with my impression about a lot of things in her job. I'm always a little surprised when she talks about calling the doctor saying I need X, Y and Z and the doctor just being like cool I'll put in the order. Obviously, not all doctors are like that but it seems like the vast majority defer to the nurses in a lot of situations. This is completely different than the conception I had of healthcare before I met her.