From what has been presented here, there is no way to make any determination what so ever. 41 is extremely young to die of an MI irregardless of what happened at one hospital or the other unless there were other contributing factors in the history which we do not have. Congenital defects? Weight? Comorbidities? Drug use? Smoking?
Also, there is no information here about what he presented to the first ER for, what he was worked up for, why he left, etc. It could range from presenting for chest pain and not being worked up for it properly, leaving AMA, presenting for other conditions and having those worked up properly and never mentioning chest pain.
Finally, there is no indication here that he was having chest pain (or not having it), just an assumption that he presented to the first ER with chest pain as his CC. So, without knowing anything more about the first visit it is very difficult to discuss what "went wrong" at the first visit as we don't know enough about that first visit to know what did or didn't happen.
Having said all that, if someone presents with chest pain, discomfort, etc. in my ER, they get worked up for cardiac period. There is no judgement call in it. Full monitor, IV, EKG, chest xray, full labs, etc. Unless they are allergic they get ASA. Nitro unless ED med or R MI, etc. The only way this protocol is not implemented or is aborted is if the doc convinces the RN that it's not cardiac and we are not easily convinced.
One of my chronic pain pts came in and saw the full waiting room, decided she had chest pain as they got in faster than her usual headache. She got whisked away to a cardiac room, two IVs, EKG, full monitor, the whole works until she begged us to stop. We told her the only way it was going to stop was if she signed out AMA, which she finally did, then went back to triage 10 minutes later to complain of a headache! lol
My point is that we (and every ER I know of) take chest pain very, very seriously. As others have mentioned, if his presentation was one where the pain had just started, then the enzymes would not have been elevated. If it was a NSTEMI, then the EKG could have reported normal. Neg for cardiomegaly, than the chest xray would have appeared normal. If there were no other SxS of cardiac and the pt described the pain in such a way to be consistent with epigastric, or muscle pain and tx of those conditions relieved the pain, then it is possible that the pt could have been misdiagnosed. Likely? not really very high, in fact very, very minimal, but theoretically possible.
If you do know more, it would be an interesting case study for us all to see if there was anything that could have been done differently that would have changed the outcome. Please let us know if you find out autopsy results or the details of the first hospital visit. I seriously doubt that there was negligence at the root cause of this situation.