The Brits showed this ad from the patient's perspective:
Although one would hope the symptoms wouldn't get to this extreme, the ad makes the point that heart attacks aren't really just about chest pain: but also chest or arm tightness or a discomfort, dizziness, shortness of breath, nausea, vomiting, sweating, and the like.
But back pain, especially between the scapula, was not mentioned, nor was incessant burping typical with some inferior myocardial infarctions (lower wall heart attacks).
Not only are people unfamiliar with the more common symptoms of heart attacks, but there's a tremendous amount of denial when they happen to one of us. Worse yet, many people I have seen were ashamed to call the ambulance because they didn't like the idea of flashing lights and sirens in front of their residence.
And one more thing to consider: if a friend wants to call an ambulance for you, let them. Remember they are objective observers, and might just save your life even despite yourself.