Atrial fibrillation, or “A Fib”, is the most common heart rhythm disorder, affecting roughly 2.2 million Americans. Each year, more than 150,000 new cases are diagnosed.

A Fib affects the heart’s two small upper chambers, or atria. During A Fib, the electrical impulses which cause contractions in the upper chambers of the heart malfunction. This causes the atria to beat very rapidly or in an uncontrolled pattern, and they are not as effective in pumping blood. Patients with A Fib often complain of a rapid heart beat, trouble catching their breath and a feeling of lightheadedness.

A Fib can occur suddenly and end spontaneously, or it may be persistent and continue indefinitely. Although it can occur at any age, it is most common in individuals over age 65. Three to five percent of individuals over age 65 have the condition, and approximately 8 percent of those over age 80 are affected.

What Causes A Fib?

The heartbeat is regulated by electrical impulses that coordinate the contraction of the heart’s four chambers (the two atria on top and two ventricles on the bottom), pumping blood efficiently throughout the body. During A Fib, electrical signals to the atria cause them to beat out of their normal rhythm, reducing their pumping efficiency.

A Fib may arise without a known cause (idiopathic A Fib), but several conditions are associated with development of this condition. These include heart and vascular disease, thyroid disease and lung disease. A family history of A Fib is also a risk factor, as are alcohol and tobacco use. It is more common in men than in women, and also more common in the elderly.

A Fib can occur suddenly and end spontaneously (paroxysmal A Fib), or it may be persistent and continue indefinitely. A Fib is often asymptomatic, but symptoms can include palpitations (awareness of the heart beating abnormally), chronic fatigue, exercise intolerance, malaise and shortness of breath.

Types of A Fib

There are different types of atrial fibrillation, characterized by their duration and response to treatment.

• Paroxysmal A Fib - If A Fib occurs periodically and ends spontaneously, it is known as paroxysmal A Fib. Symptoms of paroxysmal A Fib can range from mild to severe, with episodes occurring a few times a year or daily. Their duration is usually unpredictable, sometimes lasting just seconds or continuing for hours or longer.
• Persistent or Chronic A Fib - With persistent A Fib, the irregular heart rhythm will not return to normal on it’s own but will respond to treatment.
• Permanent A Fib - This condition occurs when the irregular heart rhythm can’t be corrected with treatment and continues indefinitely.

Health Risks

Atrial fibrillation is in itself not generally life threatening. Left untreated, however, it can lead to more serious health problems such as heart failure or heart muscle disease.

People with A Fib are also at a three to five times greater risk of stroke. This is because A Fib reduces the efficiency of blood flow through the heart’s upper chambers, creating the potential for blood to pool and clot within the heart. If a blood clot is then released into the blood stream, it can obstruct circulation to the brain and cause a stroke. The American Heart Association estimates that approximately 105,000 strokes occur each year in individuals with A Fib, making it responsible for approximately 15 percent of total cases and a leading cause of stroke.