Atrial fibrillation, also known as AFib or AF, often causes the heart to beat faster with an abnormal rhythm. It is the most common chronic, irregular heart rhythm in the U. S. It strikes more than two and half million people in America and the incidence of AFib rises with age. It’s most prevalent in people over the age of 65 affecting about nine per cent of this population; and there isn’t a predictable pattern to the irregular heart rhythm (arrhythmia).