Atrial Fibrillation

Causes

The chance of developing atrial fibrillation increases as a person ages. Fewer than one in 100 people in their 50s has atrial fibrillation, but about 10 in 100 people in their 80s
have it.

Most people with atrial fibrillation have heart disease. Some people have atherosclerosis (hardening of the arteries). Others have different heart problems, such as:

• Long-term high blood pressure (hypertension)
• Abnormalities of the heart valves (thin tissues that keep blood flowing in one direction through the heart)
• Pericarditis (inflammation of the saclike covering of the heart, the pericardium)
• Abnormalities of the heart's pumping function
• Dysfunction of the heart's natural pacemaker, the sinus node

One-third of those who have atrial fibrillation have no underlying heart disease. Though the cause of atrial fibrillation is often unknown, possible causes include:

• An overactive thyroid or other metabolic imbalance
• Damage or microscopic abnormalities in the muscles of the atria (upper heart chambers)
• Abnormalities within heart cells
• Abnormal electrical properties of groups of heart cells
• Emphysema or other lung diseases
• Sleep apnea and other sleep disturbances
• Exposure to heart stimulants, such as caffeine, tobacco or alcohol
• Rapidly firing triggers (hot spots) — often located in the veins that return blood from the lungs to the heart (pulmonary veins) — that cause the atria to fibrillate