Go buy a box and take with food before bedtime later on. depending on your body you might by day three feel less acid or heart burn which many people have no fault on their thinking it's a MI etc. If it is truly a ferocious heart attack, down you go like a tree. Just do the County Coroner a favor. Tuck both of your arms to your chest. It makes it much easier to load you into a body bag in a few hours time after the rigor Mortis has started.