My father presented with a-fib (it seems to run in our family) for what he thought was the first time while excecising (treadmill) at the local gym back in Feb/March. He stepped off the treadmill for a few minutes and converted to sinus rythm on his own. He visited the cardiologist who ordered a 24 hour holter monitor which turned up that he is in afib approximately 7% of every day (and he does not feel it). He has no other known heart problems (is on cholosterol lowering medication). He is 64. Anyway, to finally get to the point, he is to be on coumadin for the rest of his life.
That is a great question!! Have you asked your cardiologist about giving it a try without the coumadin? It is possible that you will be required to continue taking it, but if the episode was definitely related to the thyroid med, it's worse asking.
What a great job!! Beautiful up there in the sky : )