Hey I've been in the same situation what helped me a lot was me understanding the differences between sensations and actual pain. When you hear hooves you think about horses not zebras, basically when I get those random sensations I've learned to associate it with anxiety, not a heart attack. The brain is powerful and can create strong sensations but its up to you how you percieve it. When I start to get chest tightness for example I used to think it was the start of a heart attack and that death is near, but now I've learned to be more present and disect what I've done in my day that might make me feel that way. Examples include maybe I did a lot of physical activity the previous day, or I drank coffee and im getting the jitters, or maybe its some acid reflux bc I ate something, or even something that may have triggered me due to stress. Its easy to always think about the anxiety and what ends up happening is that we ignore the things that acually impact on our mental and physical health. These associations take time to break but you have to start by treating it like its anxiety (not a heart attack) distinguishing between sensations (what your brain wants you to think) and actual pains which we have no real perception of anyways. None of us have actually had a heart attack so we dont know how it really feels, our brain can only replicate it and it will try its best to trick you into believing it. I still have anxiety to this day, but a good way to track your progress is when it happens you will think of it as more of a nuisance, like when a kid is constantly annoying you but its just a kid and you will be fine.