I had those chest pressure/close to heart attack feelings too and very frequently until I went for a Vega test, were it was found that I had various food intollerances, primarily wheat/gluten (the intollerances were likely a consequnce of mercury poisoning).
Once I stopped eating anything with gluten, those chest pressure feeling vanished within days.
This was all even before I had my amalgans removed, so I would encourage anyone with those chest pressure feeling to get a food intollerance test (regardless if you still have amalgams or not), personally I think the Vega test is very reliable and much quicker and easier than traditional prick/patch tests, if done by an experienced Vega tester.