I would ask your doctor for a definitive answer but from what I understand if the rate is not causing you any distressing symptoms like shortness of breath or chest pain your low rate is likely not an issue and is probably due to all the good cardio you have given it over the years.
Sorry I cannot help but I feel the same as you. Before my stupid pvcs started, I was running several miles after work. Now I do not even like to walk fast.
I hate how thses have taken control of my life.