I am glad to hear they are ok.

I don't think the cardio myopathy is completely without dangers. My co-worker Gudrun had two cats, sisters who had it. She found out when one day Lisa suddenly died- within 15 minutes at the age of about 7. She then had Mona checked and of course she had it too. She is getting beta blockers now for like 2 years every morning and evening! But she's doing fine. She even had teeth extracted under anesthesia- but of course for a kitty like this anesthesia is a risk.

But there are different types of cardiomyopathy (which mainly means a weak heart muscle) I hope you can find more about it.