Hello,
It looks like you had extensive tests to rule out a heart disease and all the tests came out normal and did not show any heart disease. This is important because probably no other medical conditon which gives similar symptoms can be as life threatening as heart disease . I suggest to you to see another cardiologist as a second opinion so nothing is missed relating to the heart. If again nothing is found probably you do not have any heart problem . It is something else, as i mentioned in my previous post such as esophageal spasm. A pinched nerve in your upper back or neck may also needs to be ruled out.
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