Is atrial fibrillation a serious condition? my friend is 45 and has it.

Not usually: Atrial fibrillation may be a consequence of structural abnormalities of the heart, which can indeed be serious. However, if the rhythm disturbance is the only abnormality then it can usually be controlled sufficiently that the patient can be free of symptoms. In older patients with af there is significant risk of stroke, but this too can be mitigated by treatment to reduce blood clots.

Yes.: Atrial fibrillation increase the risk of stroke, which can be disabling or fatal. Strokes from af tend to be worse than non-af strokes. Additionally, if the af causes a fast pulse for a prolonged period of time, this may lead to weakening of the heart and cause heart failure. A very fast pulse, even for a short period, can precipitate a heart attack in someone with underlying blocked arteries.