Atrial fibrillation is a common complication following bypass surgery. It’s often temporary and goes away without causing issues, but it may pose other risks.

A coronary artery bypass surgery, also known as bypass surgery, is a procedure that involves taking a blood vessel from another part of your body and using it to divert blood around a blocked artery in your heart.

Atrial fibrillation (AFib) is an irregular heartbeat characterized by atypical beating in your heart’s upper two chambers. It often causes a rapid heart rate.

AFib is a common side effect of bypass surgery. It’s often temporary, but research suggests that it might be associated with higher short- and long-term risks of cardiovascular complications, including stroke.

Here, we examine why AFib develops after bypass surgery and how it’s managed.

Learn more about atrial fibrillation.

AFib is the most common complication of heart surgery. The reason why AFib often develops after bypass surgery is complex and involves many different factors, including:

  • physical stress and inflammation in your heart caused by the procedure
  • changes to your sympathetic nervous system after surgery
  • medication side effects
  • restricted blood supply to the atrium (ischemia)
  • imbalances in electrolytes and other substances in your blood
  • the development of a serious complication called sepsis
  • changes in blood flow in your heart

More than 200,000 people undergo a coronary bypass every year in the United States. AFib is the most common complication, and it occurs in 15–45% of people. It often goes away within 6 weeks.

Some research shows that people who develop AFib may have a 2–4 times increased risk of stroke.

Symptoms of AFib include:

In some cases, AFib doesn’t cause any symptoms, and you may not realize you have it.

Learn more about the symptoms of AFib.

Developing AFib after bypass surgery seems to occur more frequently in people with certain health conditions or other risk factors.

In a 2021 review of studies, researchers identified the following risk factors for developing AFib after bypass surgery:

  • being an older adult
  • having high blood pressure
  • having preexisting kidney failure
  • having higher presurgery serum creatinine levels
  • having lower presurgery hemoglobin levels
  • having lower left ventricular ejection fraction
  • undergoing a longer surgery
  • having a need for a second surgery
  • taking inotropes, a class of medication that helps the heart contract, postsurgery
  • experiencing kidney failure postsurgery

Studies suggest that people who develop AFib after bypass surgery tend to develop it 2–3 days day after the procedure.

People who develop AFib may be at an increased risk of stroke and other cardiovascular complications in the short and long term.

In a 2021 study, researchers examined the long-term outlook of 7,368 people who developed AFib following bypass surgery in Sweden from 2007–2015 at a median follow-up period of 4.5 years.

The researchers found that AFib was associated with an increased risk of:

  • ischemic stroke by 18% (95% confidence intervals from 5–32%)
  • thromboembolic episodes by 16% (95% confidence intervals from 5–28%)
  • heart failure requiring hospitalization by 35% (95% confidence intervals from 21–51%)
  • recurrent AFib by 316% (95% confidence intervals from 276–360%)

Other studies report that people who develop AFib postsurgery have about a four times elevated risk of stroke in the years following the procedure.

Doctors can diagnose AFib with a standard 12-lead electrocardiogram or continuous cardiac monitoring (telemetry).

Doctors use telemetry to diagnose AFib postsurgery in about 75% of people. Telemetry involves continuously monitoring your heart rate for days to identify abnormalities in your heart rhythm.

Current international guidelines recommend oral anticoagulation for AFib that develops after bypass surgery.

The 2023 ACC/AHA/ACCP/HRS guidelines for diagnosing and managing AFib strongly recommend the following treatments for people who develop AFib postsurgery:

  • beta-blockers, which are recommended for managing heart rate; if ineffective or if they can’t be administered due to a health concern, the guidelines recommend using calcium channel blockers
  • heart rate or heart rhythm control medications, which are recommended as an initial therapy
  • direct current cardioversion, in which a controlled shock is applied to the heart
  • antiarrhythmic drug therapy, which is recommended for people with AFib who haven’t taken anticoagulation medications and have had AFib for more than 48 hours

The guidelines also recommend that doctors administer anticoagulation medications when deemed safe for 60 days postsurgery unless complications develop.

In addition, for people taking heart rate control medications, doctors can assess their heart rhythm 30–60 days postsurgery and consider whether direct current cardioversion may be beneficial if anticoagulation medications have not helped.

Researchers are continuing to examine how to best prevent AFib after surgery.

Taking beta-blockers before heart surgery has been associated with a reduced risk of AFib. Doctors may also administer the antiarrhythmic medication amiodarone for people with a high risk of developing AFib.

Here are some frequently asked questions people have about AFib after bypass surgery.

How serious is AFib after bypass surgery?

Research from 2022 associates developing AFib after bypass surgery with longer hospital stays and an increased risk of cardiovascular incidents following surgery. However, many people recover without any long-term complications.

Does AFib go away after surgery?

AFib that develops after surgery is often temporary. Your doctor will likely recommend taking anticoagulation medications and possibly an antiarrhythmic medication to help reduce your risk of complications.

How long does AFib last after bypass surgery?

About 15–20% of cases of AFib that develop after bypass surgery go away within several hours. More than 90% of cases go away within 6 weeks.

AFib is one of the most common complications following bypass surgery. It’s often temporary and goes away without causing issues. However, people who develop AFib may be at an increased risk of stroke or other cardiovascular complications.

Some medications, like beta-blockers and amiodarone, may decrease your risk of AFib after surgery. It’s important to speak with your surgical team before your procedure to learn about how to best prepare for your procedure.