Hi there Treybabe. First, I'm glad to hear that your niece's cats had long lives without treatment. I like positive stories like that.
I was so scared when my heart kitty Marius was diagnosed with a murmur. He has a fairly high-grade murmur, so the vet has me watching him and will be doing a recheck every 6 months to see if anything has changed.

You can see the thread about his murmur here:
http://petoftheday.com/talk/showthre...d+heart+murmur

**hugs**