Atrial Fibrillation

Causes

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

Most people with atrial fibrillation have heart disease. Some people have coronary heart disease (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 (pericardium)
• Abnormalities of the heart's pumping function
• Dysfunction of the heart's natural pacemaker, the sinus node

One-third of the people who have atrial fibrillation don't have underlying heart disease. Though the cause 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
• 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