Atrial Fibrillation (AFib): Symptoms, Causes and Treatment

Atrial fibrillation (AFib) is the most common heart rhythm problem. The heart’s two upper chambers (the atria) quiver instead of squeezing in a steady beat, so the heartbeat becomes irregular and often fast. AFib usually isn’t deadly by itself, but it raises the risk of stroke about fivefold. Treatment aims to prevent clots and keep the heartbeat under control.

Key points

Common symptoms are a fluttering or pounding heartbeat, tiredness, shortness of breath and dizziness. Some people feel nothing.
Many people with AFib need a blood thinner to lower their stroke risk. Your age and other health conditions decide this.
Medicines can slow the heart or restore a normal rhythm. A procedure called catheter ablation is another option.
Losing extra weight, cutting back on alcohol and treating sleep apnea and high blood pressure reduce episodes.
Call 911 for chest pain, fainting or signs of a stroke.

How the heartbeat works

The heart has four chambers. A natural pacemaker in the right atrium (the sinus node) sends an electrical signal with each beat. Both atria contract together, pushing blood into the two lower chambers (ventricles). The signal then passes through a relay point called the AV node, and the ventricles squeeze a split second later to pump blood to the body.

In atrial fibrillation, chaotic signals fire from many spots in the atria, often near the veins that bring blood back from the lungs. The atria twitch hundreds of times a minute instead of contracting. The AV node lets only some of these signals through, so the pulse feels irregular and is often fast. Blood can pool in a small pouch of the left atrium and form a clot. If the clot travels to the brain, it causes a stroke.

How AFib differs from other rhythm problems

Premature atrial contractions are extra beats that come early from the atria. They feel like a skipped beat or a flip-flop and are usually harmless.
Atrial flutter is a fast but organized rhythm in the atria. It’s treated much like AFib.
Heart block is a slow rhythm, where signals from the atria are delayed or stopped before they reach the ventricles. It may need a pacemaker.

Types of atrial fibrillation

Paroxysmal: episodes come and go and stop on their own, often within a day or two and always within a week.
Persistent: episodes last more than a week or need treatment to stop.
Long-standing persistent: AFib that has lasted more than a year.
Permanent: you and your doctor decide to stop trying to restore a normal rhythm and focus on controlling the heart rate.

Without treatment, AFib often happens more often and lasts longer over time.

What causes atrial fibrillation

AFib becomes more common with age, especially after 65. Risk factors include:

High blood pressure
Coronary artery disease, heart failure and heart valve problems
Obesity, diabetes and obstructive sleep apnea
Heavy drinking, including binge drinking
An overactive thyroid
Lung disease
Recent heart or chest surgery
A family history of AFib
Years of intense endurance exercise

Sometimes no cause is found.

RELATED REPORTS

Frailty in older adults with atrial fibrillation is multifactorial and associated with metabolic and cognitive factors

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Symptoms

A racing, pounding, fluttering or irregular heartbeat
Tiredness and less energy for exercise
Shortness of breath
Dizziness or lightheadedness
Chest discomfort
Fainting, which is less common

Many people have no symptoms, and AFib is found during a checkup or by a smartwatch.

How it’s diagnosed

Electrocardiogram (ECG). Stickers on the chest record the heart’s electrical activity and confirm AFib.
Wearable monitors. If AFib comes and goes, you may wear a monitor for a day to several weeks. Options include a Holter monitor, a patch, an event monitor, or mobile cardiac outpatient telemetry (MCOT), which sends readings to a monitoring center as you go about your day. A tiny recorder placed under the skin can track the rhythm for years.
Echocardiogram. An ultrasound shows the heart’s size, pumping strength and valves.
Blood tests check thyroid and kidney function and blood salts.
A sleep study, if sleep apnea is possible.

How atrial fibrillation is treated

Preventing stroke

Your doctor uses a simple scoring system based on your age, sex and conditions such as high blood pressure, diabetes, heart failure and past stroke. If your risk is high enough, you’ll be offered a blood thinner (anticoagulant), such as apixaban (Eliquis), rivaroxaban (Xarelto), dabigatran or edoxaban. Warfarin is still used for people with a mechanical heart valve or certain valve disease. Aspirin isn’t recommended to prevent stroke in AFib. Blood thinners raise the risk of bleeding, so your doctor will weigh that too. For people who can’t take a blood thinner long term, a small device can seal off the pouch where clots form (left atrial appendage closure).

Slowing the heart rate

Beta-blockers such as metoprolol, calcium channel blockers such as diltiazem, and sometimes digoxin keep the heart from beating too fast.

Restoring a normal rhythm

Cardioversion: a quick, timed shock to the chest under brief sedation, or medicine, to reset the rhythm. You usually take a blood thinner before and after.
Antiarrhythmic drugs help keep a normal rhythm. They include flecainide, propafenone, sotalol, dofetilide, dronedarone and amiodarone. Some need close monitoring for side effects.
Catheter ablation: thin tubes are passed through a vein in the groin to the heart. The doctor uses heat, cold or short electrical pulses (pulsed field ablation) to make tiny scars that block the faulty signals. It often works better than medicine, and some people need a second procedure.

Treating the triggers

Losing about 10% of your body weight, cutting back on alcohol, using CPAP for sleep apnea, controlling blood pressure and blood sugar, quitting smoking and regular moderate exercise all lower how often AFib happens.

When to see a doctor

See your doctor if you notice an irregular or racing heartbeat, or your smartwatch flags possible AFib. If you take a blood thinner, call for black or bloody stools, blood in urine, or bleeding that won’t stop.

Call 911 for chest pain, fainting, severe shortness of breath, or stroke signs: face drooping, arm or leg weakness, or trouble speaking. Also call after a hard fall or head injury while on a blood thinner.

Common questions about atrial fibrillation

Can atrial fibrillation go away?

Sometimes. Episodes of paroxysmal AFib stop on their own, and AFib caused by a short-term trigger, such as surgery, an infection or heavy drinking, may not return once the trigger passes. For most people, though, AFib comes back over time. Ablation, medicines and healthier habits can keep it away for long periods.

Is atrial fibrillation dangerous?

AFib itself rarely causes sudden death, but it can lead to serious problems. The biggest risk is stroke from a blood clot. A fast heart rate that goes on for weeks can also weaken the heart and cause heart failure. Treatment greatly lowers both risks.

Can I drink coffee or alcohol with AFib?

Most people with AFib can drink coffee in normal amounts, since studies haven’t shown that it triggers episodes for most people. Alcohol is different. Even moderate drinking raises the chance of episodes, and in one trial, regular drinkers who stopped had fewer episodes. Energy drinks and decongestants can also trigger it.

Can a smartwatch detect AFib?

Many smartwatches and phone-linked devices can spot an irregular rhythm that may be AFib and record a single-lead ECG. They miss some episodes and can give false alarms, so a doctor needs to confirm the result with a standard ECG or monitor. They’re also useful for tracking episodes after diagnosis.