Fattycat's heart murmur, talk me down!

[Toddlerteaplease]

Took Fatty and Snorg in for a dental this morning and saw on the vets notes that Fattycat’s heart murmur was graded as a 4/5. When I’ve asked about the grade before the Vets were very vague about it and therefore I decided that as she was asymptomatic, not to have it investigated further. (Surgeon who did her jaw said there was no need). So I’m freaking out about it a bit. They are going to do an X ray and see if her heart is enlarged or any fluid in her lungs.
She gets absolutely terrified when at the vets. Would that make it seem worse than it is?
Photo for her fans.

My lovely boy lived to 18 with a heart murmur, and he was healthy right up to the last few days. I still remember how scared I was when the vet found it, but honestly it never affected him at all. Try not to panic.

Her heart is really bad and she’s got cardiomyopathy. Almost certainly hereditary but also caused by the way she was kept in her first five years of life. Not in heart failure yet but not far off it. She’s been started on medication, hopefully it will help her.