I am not exactly sure about if heart problems related to B12 deficiencies are reversible, but I can say that you can have some symptoms of B12 deficiencies and not be anemic. It is rare to be deficient unless you are vegetarian or you lack an enzyme in your intestine needed to absorb B12. B12 is found in foods such as fish, shellfish, meat, and dairy products. Taking a multivitamin is always a good idea, and maybe increasing some of this foods (if your not a vegetarian) could help. Also, if your levels do come back low, then you may need to look at getting IM injections of B12. I hope that your problems are due to B12 deficiency because there is an easy fix for that. Good luck, and hopefully you can get some answers!