I've had heart health anxiety for 11yrs now. I'm 34,5'5 180lbs and a smoker(yes I know I need to stop,easier said than done),blood pressure is good,heart rate runs alittle high but is good. Always back and forth to the ER and dr and had all sorts of tests done. Nothing ever convinced me that my heart was ok.Was on Klonopin for it for about 3yrs then decided to go off it because I had grown dependent on it. I would freak out if I didn't take it at the same times everyday. Anyway,fast forward to now..last Aug I went to the Er with chest pain and tachycardia..they did ecg ,blood work and ct scan. Everything came back fine except my ecg was unspecified(inverted twave). My dr had me wear an event moniter for a week and it came back good with normal sinus tachycardia. I ended up back in the ER in June with chest pain and they did the same tests and all came back good except for the ecg again. So the ER dr referred me to a cardiologist to have things checked over. The cardiologist did a heart scan(0% hard calcium),echo/stress test,pulmonary function test to make sure it's not my lungs..all came back good. I go for a cardiac MRI and velocity test next week and he said if it comes back good then he can absolutely and definitively rule out that my heart is the problem and that it's all anxiety causing everything that's wrong...If it does come back good,how do I convince my brain that there's nothing wrong with my heart and that I'm not gonna drop dead from a heart attack or cardiac arrest?
hey… im so sorry that anxiety is doing this to you. i know what youre going through. it takes time and effort to convince yourself that ur ok. its doable tho. firstly, you have to try to remember when you become scared that you have felt this before… its not a new feeling. you have been thru this or something quite similar already… you made it thru that time and the time before that. you came out of it just fine and as healthy as a horse. when you start realizing these things, the next time you feel it, your brain automatically associates it with just a fear and you eventually feel better. im not saying that it wont bother you, it will… but eventually it becomes manageable. after a while it becomes almost unnoticeable… you are going to be fine. like i said, it takes some time and effort, but it is doable. practice telling yourself positive things. your brain thinks in images… even if you say “im not having a heart problem”, all ur brain recognizes is images of a heart problem and it gets you scared… instead, say things like “i am healthy”. “i will always be happy”… that way your bran starts seeing positive things and you feel these positive things instead. i know itll all work out for you. i promise you, you are going to be just fine. 
you sre not alone.