[Porsche-O-Phile]

Exactly - be careful. Cardiomyopathy is what killed my cat, Charlie a couple of years ago. It was very evident in the autopsy photos that the heart walls were much thicker than they should have been which reduced chamber volume, etc. The vet was 99% sure that's what did him in. No warning either. You should go to a cardiac specialist if you haven't already to fully understand what you're up against here and what if anything can be done. It doesn't sound like it's anything to blow off.