There are many risk factors for AFib, including age, hypertension, and the presence of structural heart disease.  All of these may contribute to development of AFib, but probably the major factor driving the big increase in the absolute number of patients with AFib in the United States is the fact that the overall population is aging.  With greater age comes greater risk for development of AFib, and as seen in Figure 3,[3] the projected increase in patients with AFib in the United States and worldwide over the next few decades is staggering.