This sounds very strange to me. It is not good. I can understand your concern and I hope you can find out what the reasons could possibly be. I have been a patient at "Mother Mayo" since about 1990 and this would be very unusual unless a patient made a miraculous recovery and no longer needed specialty care. I can see referring you to another cardiologist but not primary care - not with a valve and an aneurysm,
Have you been seen in Cardiology at Mother Mayo or at one of the Mayo Health System satellites? It is possible that policies and procedures at a satellite may be different than at Mother Mayo.
I ask this because you mentioned primary care, which has not been available to most patients at Mother Mayo since about 2015. The exceptions may be former Mayo staff members and maybe other patients for whom they feel primary care/internal medicine is medically necessary and appropriate.
Please keep us posted. I second the suggestion to see the patient advocate for the satellite where you get care or at Mother Mayo.