G'day Dave
I had a murmur as a kid which was pretty benign, but for related reasons I ended up getting a new aorta in 2004.
I was grounded for 12 weeks post-op, saw the Docs, got the reports and went back to work
I retain a Class 1 medical and a ATPL and I will do so until (aged about 50 I hope) eventually my valve folds up and gets replaced.
Once that happens, I will probably have a limitation on my Class 1:
"May only fly as or with a co-pilot".
Murmurs can be caused by a number of things - it is important that you know what causes yours so you can manage it (if required)
Good luck