hello and welcome to neurotalk ... i don't have any answers about b12 deficiency and heart problems ... however i can relate to deficiencies and how different ones can and do cause symptoms which doctors have a hard time acknowledging .... personally i think its because they are looking for something bigger .... can't see the tree for the forest type of mentality ... anyway ... enough said ... here at NT you will find alot of friendly and supportive people ... here is a link to our fantastic forum on vitamins .... maybe there you will be able to find some answers ... http://neurotalk.psychcentral.com/forum49.html and again ...