I Am 69 Years Old Very Active. I Had A

I am 69 years old very active. I had a mitral valve replaced do to mitral valve stenosis with a tissue valve about 7 years ago. last year I got dehydrated and went into AFIB I was put on eliquis I don't know if it was caused by the valve or not, doing OK now. should I be concerned? all I read is eliquis is not to be used for AFIB caused by a valve or valve replacement. why is eliquis not used? is this a big problem?
Robert W. Hayman