Thanks for writing in. I am a qualified and certified cardiologist. I read your question with diligence. Heart failure
3 years after surgery needs evaluation. There are two obvious possibility, I presume it was a bio prosthetic valve and it has started showing degeneration or when the surgery was done there was ongoing muscle disease
component apart from mechanical component due to valve. After the mechanical component was taken care of, the muscle component contributing to failure progressed. She needs to be examined by a cardiologist and evaluated after thorough examination with EKG, Chest X-ray and echocardiography
. My feeling is she would do well with conservative treatment for failure. Good Luck and Best Wishes.
Dr Anil Grover