My Question: I'm 77; Diagnosed With A Fib. Otherwise Symptomatic

My question: I'm 77; diagnosed with A Fib. Otherwise symptomatic free. Did have an episode of graves disease 35 years ago that lasted long enough (months) for me to lose about 20 pounds and then spontaneously ceased before any treatment. I see there is a correlation. I am at a healthy weight and exercise regularly. How at risk am I for a stroke?