My Cavalier had an episode of CHF in April and I am trying to avoid any unecessary chemicals
Shouldn't you be asking your vet? I realize that most vets only get a basic course in nutrition, but they can certainly research it for you. Also, if you want a more holistic approach, then I suggest you find a holistic vet who would certainly be able to give you the advice you seek on healthier food options without chemicals, etc.
I have no idea what Platinum Performance is or how it is to be used, but boiled chicken and veg aren't enough. It isn't balanced at all. Dogs need all sorts of minerals, vitamins, bone meal, etc. I know, because I made my own dog food for about a year and it had a protein, brown rice, lots of veg, plus supplements.