I think the other risk is if the arrhythmia continues
for years, then it could weaken his heart. But, since he is going in
for an echo in a week and they will probably convert him, then I do not think there is a big danger of that happening.
The older a person gets, the more likely he or she is to develop atrial fibrillation. Lots of older people have it, and again, it is not dangerous in and of itself and many times (like in my case), it occurs without any underlying heart disease.