I agree I think the breeder is concerned for Ivy's welfare and that is a good thing, it is a toughie alright, but i think i would keep him myself, honestly judging by the many people here including myself who have kitties with heart murmurs they rarely have many problems, but of course Ivy might be the exception, you really do have to weigh up the pros and cons,and do what is best for you and Ivy in the long run.