Gall bladder surgery for heart patient

My dear friend, almost 90, is having her gall bladder removed.  She's experiencing atrial fibrillation (for months), had a cardio-conversion 12/22, which only lasted 2 weeks.  She's scheduled for another one but now the gall bladder issue is more pressing.

What increased risks might she have during the surgery, with her heart condition?  She's terribly weak (from weeks of not being able to eat) and nauseous.  

She's supposed to be released after one hour of recovery; is this normal, particularly for her age and in her state of health?

[Cleveland Clinic]

I am not sure what the recovery for such a surgery is, but if you have questions regarding this you may want to ask another surgeon for a second opinion. The important thing you realize is that she is 90 years old we do not have good information on perisurgical risk modification in patients of such advanced age. The best we can do is to extrapolate from younger patients, and hope these principles apply. First is the issue of anticoagulation: if she is on coumadin then this would have to be stopped for the surgery, so she will have a perioperative risk of stroke. Second is the need for rate control during surgery, as this imparts an additional risk for myocardial infarction as well as stroke perioperatively.