Those tests are a snapshot of today and not a prediction of the future.
I am pretty much on the verge of tears typing now just thinking about the last one I lost to DCM.
I had the same tests run on her and even had her results sent off and looked at by doggie heart specialists in Florida. She passed all the tests just fine. I forget how many months later it was before she suddenly starting behaving 'off' and I noticed something was not right with her. 7 or 8 months later before the first noticeable symptoms in our case? A few months later at most before things got really bad and she started refusing food.
DCM can sometimes be like a bullet that comes out of nowhere.
I plan to snuggle up a little closer tonight with the girls I have here now and be glad for every day they are around.