Any type a virus can go to a heart just like it can go to the brain. When a virus attacks the heart, usually pericarditis occurs. The heart sack can become hard and harm the heart by not letting it beat as it should. Do you have any pericarditis? Did you have radiation with your breast cancer? Radiation affects the heart, lungs, and bones for years to come. My mother had breast cancer at the age of 42. She had heart failure at the age of 58 due to what was thought the radiation or sarcadosis that she had when she was 30. When she had her final heart surgery last August, the surgeon told us that the radiation really took a toll on her (that her heart was extremely hard and bones were crumblying). She did not survive and passed away at the age of 70. She had an enlarged heart at the age of 58 when she was diagnosed. Fortunately, there is a lot of progress coming in the near future for the heart. Procedures can be done to avoid open heart surgery. If it comes to the point where the doctors are talking surgery make sure to find out if you have valve disease, cardiomyopathy (heart muscle disease), or artery disease. Sometimes people have all three, which means higher risk. Do your research to make sure that the surgery cannot be done by a procedure instead of open heart. It is really scary, but there is so much that doctor and surgeons can do now. Take care and take care of your heart by eating healthy (lots of fresh vegetables and fruits is best).
Here's a website about the damage that chemotherapy can do to a heart.