Did ER visit miss true issue?

I recently went to a local ER on June 4th with severe chest pain-described as intense burning.This pain had been coming and going for about 3 days. The ER doc did bloodwork, urine, an ECG and diagnosed the pain as epigastric. I was prescribed Nexium and sent home with recommendations of a stress test at a later date to rule out any other issues. Four days later I went to my local doctor with the same issues after the pain persisted. After an ECG and bloodwork, I was immediately rushed to a local Cardiac Care Unit-after a check, a 98% blockage was located in my right carotid artery. A stent was placed, and I was told I also have a 55% blockage in my left artery. This is being treated with meds.My cardio doc told me I was lucky to be alive. I know ER doctors are under a huge amount of pressure and have to think quickly, but do any of these results show a "flaw" in the ER diagnosis?

ECG-right atrial enlargement, T wave abnormality, consider anterior ischemia, abnormal ecg
Blood-troponin .02, cratine kinase 236, amylase 57, lipase 24
These are initial results from ER visit. Not trying to place blame, just looking for knowledge in case of future issues. Thanks for your consideration.