The heartbeat is controlled by an electrical conduction system that sends impulses to the heart muscle causing it to rhythmically expand and contract. Sometimes the heart's electrical conduction system loses its regular pattern, which can cause many different heart rhythm problems. One of these is atrial fibrillation (AF or Afib).
In AF, the electrical impulses are no longer coming from the heart's natural pacemaker (the sinus node), but from the heart's top chambers (atria). Compared to the typical impulses, which occur 60 to 70 times per minute, in AF the charges are very rapid, more than 300 times per minute. The rapid, uncoordinated muscle contractions that result prevent the heart from pumping effectively. The abnormal impulses in the atria also spill over to the heart's main pumping chambers (the ventricles), causing them to beat rapidly and irregularly as well.
AF can be continuous (persistent AF), or episodes may alternate with periods of normal heart rhythm, a condition known as paroxysmal AF. When the rhythm disturbance has lasted for more than a week, it is considered persistent AF.
What are the symptoms of atrial fibrillation?
Symptoms of AF typically include a racing, irregular, or uncomfortable heartbeat, or a sensation of a “flopping” in the chest. Some people also experience dizziness, chest pain, and sweating. Not all people with AF experience symptoms.
How common is atrial fibrillation?
AF is the most common heart rhythm disorder, affecting an estimated 2.2 million Americans, or about 1 in 100 people.1, 2 According to the US Census Bureau, the number of people affected by AF is projected to be more than 12 million by the year 2050.
Although men are 1.5 times more likely than women to develop AF,3, 4 the actual numbers of women and men with AF are roughly the same because AF is more common in older people and women tend to live longer than men.5 As with many heart problems, women who develop AF tend to do so later in life than men, at an average age of 75 (compared to 67 in men).6
AF itself is not usually deadly, but it can lead to other problems such as chronic fatigue, heart failure and, most importantly, stroke. There is no difference in the mortality rate between men and women with AF.7