Atrial Fibrillation: Causes, Risk Factors, and Triggers

Medically Reviewed by James Beckerman, MD, FACC on June 27, 2022
5 min read

Atrial fibrillation (AFib) is the most common problem with your heartbeat's rate or rhythm.

The basic cause of AFib is disorganized signals that make your heart's two upper chambers (the atria) squeeze very fast and out of sync. They contract so quickly that the heart walls quiver, or fibrillate.

Damage to your heart's electrical system can cause AFib. This damage often results from other conditions that affect the heart. But in at least 1 of every 10 AFib cases, other things may be at play. Sometimes, doctors can't figure out what's causing atrial fibrillation.

Even after you've been diagnosed with the condition, you may be able to control your AFib and avoid having an episode if you know what triggers them for you.

Things that most often lead to atrial fibrillation Include:


Age: Your odds go up as you get older, especially after you're 60. In part, that’s because you’re more likely to get heart disease and other conditions that can cause AFib.

Genes: AFib is a hereditary condition. That means a part of the cause is in the genes you get from your parents at birth. If someone in your close family had or has it, there's a greater risk for you, too.

Heart disease: AFib is a problem with your heart. So, other heart issues raise your chances of having it, like:

Heart conditions like these raise your chances for AFib because they create physical stress and stretch the tissues in the upper left chamber of the heart, says Ayman Hussein, MD, co-director of the Atrial Fibrillation Center at Cleveland Clinic. The stress and stretching lead to changes in the electrical properties of cells, as well as changes in the structure of the heart, like the upper chamber getting larger and more scarred. The combination of these things can make you more likely to have AFib.

If you have AFib and another heart condition, get treatment as soon as possible.

Sick sinus syndrome: This isn’t the same as the sinuses in your head. The sinus node is a group of cells that control your heartbeat. Think of it as your heart’s own natural pacemaker. Problems with it that can lead to AFib include:

  • Your heart's electrical signals misfire.
  • Your heart rate alternates between fast and slow.

Heart attack: When the artery that supplies blood to the atria is blocked, it can damage atrial tissue and lead to AFib.

But AFib doesn’t generally cause heart attacks, unless the heart rate is fast and puts the heart under stress.

Heart surgery: AFib is the most common complication. It will happen to 2 or 3 out of every 10 people recovering from a heart operation.

High blood pressure: It’s the most common condition linked to AFib. It can make the atria, or upper chambers of your heart, get bigger, which makes it work harder.

Lung disease: This includes chronic obstructive pulmonary disease (COPD), emphysema, or a blood clot in your lung (pulmonary embolism). COPD in particular often comes along with high blood pressure, heart disease, ventricle problems, and other problems that play a role in AFib, such as:

  • Low blood oxygen and high carbon dioxide levels
  • Cigarette smoking
  • Cardiac autonomic dysfunction -- your autonomic nervous system controls your heartbeat. In lung disease, it can get out of whack.
  • Inhaled medications that boost your heart rate

An overactive thyroid gland (hyperthyroidism): It speeds up everything in your body, including your heart.

Obesity, diabetes, and metabolic syndrome: Not only are these conditions often linked with hypertension, they may also make it harder for your heart to empty. And they cause other physical changes that raise your risk of atrial fibrillation.

Sleep apnea: Each time you’re jarred awake by lack of oxygen, it puts a mechanical stress on and causes chemical changes inside your heart. Plus, over time, sleep apnea can lead to conditions like high blood pressure and obesity, which make AFib more likely.

Infections caused by a virus: The resulting inflammation could cause changes to your heart.

Medication: Research suggests that people who take high doses of steroids -- perhaps for asthma or other conditions -- may be more likely to get AFib. If your chances are higher anyway, this treatment can trigger an episode. So can over-the-counter cold medications with caffeine or other ingredients that rev up your heart rate.

No clear cause: Sometimes doctors can’t find an obvious reason why someone gets AFib. There’s an upside when this happens in people under 65 years old who don’t have health conditions linked to AFib. Their chances of getting blood clots and strokes are a lot lower, compared to people who are older or who have clear causes for their AFib.

You may notice that certain things cause your AFib symptoms to flare up. Some common triggers are:

  • Stimulants: Caffeine, cigarettes, and other things that rev up your system can set off AFib. Caffeine will probably affect you more if you don't usually drink it.
  • Alcohol: For some people, binge drinking is a trigger. But for others, even a modest amount can trigger AFib.
  • Stress and worry: When you're under a lot of pressure or feeling worn out, it could trigger an episode or make your symptoms worse.
  • Exercise that raises your heart rate above a certain point (but it’s still important to get exercise)
  • Poor sleep


Some AFib risk factors, like age and genetics, are out of your control. But a healthy lifestyle can help guard against AFib and other types of heart disease. Some steps you can take: