Like it or not, AFib is trending. It’s already being called an “epidemic,” and a top reason Americans are admitted to hospitals for heart care. In the next few years, the number of new diagnoses is expected to soar.

Prefer to sit this trend out? Us too. To find out if and how that’s possible, we asked an expert about common causes of AFib.

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Sometimes, atrial fibrillation (AFib) just happens.

Experts call it “primary AFib”: Without any good reason, your heart’s electrical system misfires, triggering an abnormal heartbeat.

“We usually see primary AFib in younger, healthier people who just have a tendency toward AFib. There’s nothing else going on,” Jude Clancy, MD, a Hartford HealthCare cardiac electrophysiologist who practices in Middlesex and Old Lyme.

> Related: Can Wearable Tech Like Smartwatches Actually Detect AFib?

But most of the time, AFib is caused by something else.

This is called — you guessed it — “secondary AFib,” and it’s driven by some underlying health condition or lifestyle factor.

Technically, the cause could be just about anything that adds to wear and tear on your heart, from viral infections to heart surgery.

“The list of possible causes is pretty extensive,” says Dr. Clancy.

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Here are 5 of the most common causes of AFib in the U.S.

Of the long list of possible AFib causes, these are at the top for Americans:

  • Uncontrolled high blood pressure
  • Sleep apnea
  • Lung diseases like COPD
  • Thyroid disease
  • Structural heart disease, like from an undetected birth condition or age-related issues

Because AFib is a serious medical condition that can lead to stroke, it’s crucial to address what’s behind it.

“If something is potentially driving AFib, we try to modify those factors, the same way someone might treat cholesterol for heart disease,” says Dr. Clancy.

Can caffeine, alcohol, nicotine and stress cause AFib?

Keep in mind: There’s AFib as a condition (your heart’s overall tendency to beat irregularly) and then there’s AFib as an episode (the times when that actually happens).

If you already have the condition, things like caffeine, alcohol, nicotine and stress can certainly trigger an episode.

“If I’m a person with AFib and I drink two Red Bulls loaded with caffeine, there’s a decent chance I’m going to go into AFib,” says Dr. Clancy.

But if you don’t already have AFib, odds are, no casual amount of caffeine, alcohol, nicotine or stress will change that. Something else usually needs to be going on — like the five common causes above.

To avoid the most common causes of AFib, practice healthy habits.

This will sound familiar: Keep an eye on your weight, blood pressure, salt intake, sleep and exercise.

“AFib’s like a lot of other things, where you’re trying to live a healthy life in general and stay on top of your important modifiable health factors,” says Dr. Clancy.

Talk to your doctor for support. If you’re one of the millions of Americans already living with AFib, your healthcare team can help you manage your condition. Better yet, they may help you avoid it altogether.