Hi Neeters and welcome.
I have a heart murmur caused by mitral valve prolapse. I was told as a child that I had probably had a strep infection that caused it but after testing as an adult I was told I was born with it. It has NEVER caused me any problems and I am now 63. I bike ride, hike, work out with weights, yoga and Pilate's on days that fibro is not a big problem. Never ever a problem with my heart. I read that other people with fibro have this also. Your doctor will watch this I'm sure. I never had any restrictions because of the murmur. I do take antibiotics before dental work This is recommended to avoid an infection which could spread to your heart.
This is a great forum with lots of nice, caring people. Glad you joined us.