Hello and welcome to Healthcare Magic. Thanks for your query.
Non-specific T wave
changes do not indicate a cardiac abnormality and you need not worry about this. You have mentioned that you have had multiple ECG, cardiac enzymes and evaluations by multiple doctors - who have all told you that you don't have a heart problem. Having treatment for hyperthyroidsm doesn't mean that you would become hypo-thyroid and so, this is unlikely to be affecting your results.
I think that these excessive worries and fear of dying are due to your anxiety
problem. Since your symptoms seem to be quite prominent and causing you this much of distress, I would advise you to seek professional help. Please see a psychiatrist
for a detailed assessment and further treatment.
Wish you all the best.
Dr. Jonas Sundarakumar