I'm so sorry.. If you don't mind me asking - when was he diagnosed with the murmur and MVD? And what grade was he?
I'm so sorry about this news.
My other dog, who passed at 17, had a heart murmur and mitro valve disease, but very minor his whole life. It did not become an issue until he was around 15 and a 1/2-16. After an ultrasound, it was discovered that he heart had enlarged. It was watched and grew a bit more and then he was put on meds. He was considered to be in CHF, but I don't know the stage. However, the medicine stabilized the growth. So, in my situation the medicine helped.