George Bush is not the only one to experience an abnormal heartbeat due to atrial fibrillation. The ailment is fairly common, doctors say, striking 1.5 million to 2 million Americans a year.
And while the president's doctors describe his arrhythmia as "benign," atrial fibrillation sometimes has serious consequences. Characterized in medical literature as "rapid, random contractions of the upper chambers of the heart, resulting in a totally irregular, often rapid heart rate," atrial fibrillation can be caused by infection, heart disease, or even ordinary stress. It is far less likely to cause permanent damage than a problem in the lower chambers, but it can cause strokes in some cases.
That's because the more troublesome cases damage heart valves and cause blood clots, which can travel to the brain. Doctors treat patients suffering abnormal heart rhythms with drugs, or where that fails, by installing pacemakers. An estimated 75,000 people suffer strokes caused by atrial fibrillation in the United States each year, according to the New England Journal of Medicine. Those strokes, about 15 percent of the 500,000 strokes a year, are often more damaging than the fibrillation.