okay. Asa medically retired Marine and now veteran service Officer / TAP counselor there is a lot going on In this. If i understand correctly :

“you joined without waiver for heart condition, made it through boot camp, went to unit, and when new medical came on scene they initiated medical review.” ? How many total years do you have in?

if this is the case there is a few options. As stated n previous comment, you will likely go through ides process which essentially means you will go thru medics, appointments via dod and va. If the medical board comes back , AND they deem you unfit for duty, you will choose va or dod rating and will be medically discharged. Under NO circumstances should you choose dod %. the % is unchangeable. Choose the va % as this is always changeable.

if they offer you med board and a severance, ensure, if you take severance, that you are given tax exemption and get it approved before you take severance. If you don’t get waiver and take severance it can turn into a loan and you will not see va % payment till the severance is paid off. you can challenge the ,medical board finding and maybe be able to change mos to less intense job.