Atrial Fibrillation Blood Clots: Symptoms, Prevention, and More

Atrial Fibrillation


  1. Atrial fibrillation (A-fib) is a type of cardiac arrhythmia, or irregular heartbeat.
  2. Blood clots are a common complication of A-fib.
  3. Blood clots can contribute to breathing problems, inconsistent blood supply, and even stroke.

Atrial fibrillation (A-fib) is a type of cardiac arrhythmia, or irregular heartbeat. In a healthy heart, blood moves into your atria and then into your ventricles. The ventricles are the lower chambers of your heart. From there, blood flows around your body and back to your heart. Electrical impulses allow each part of your heart to beat in sync with the other parts.

However, A-fib misdirects your heart’s electrical signals. This causes your heart’s two upper chambers, the atria, to beat chaotically, preventing proper blood flow through your heart. This commonly causes blood clots, a life-threatening problem associated with A-fib.

How Does Atrial Fibrillation Cause Blood Clots?


Atria that beat irregularly don’t fully contract during each heartbeat cycle. This is dangerous for several reasons. One of the biggest concerns is a blood clot. When the atria beat improperly, blood doesn’t flow properly through your heart. This can cause blood to pool in your heart’s chambers, possibly resulting in blood clots.

Blood clots can cause breathing problems, an inconsistent blood supply, and even a stroke. You’re nearly five times more likely to suffer a stroke if you have A-fib, as compared to those who don’t have A-fib.

A-fib isn’t always life-threatening. You can live your entire life without experiencing any extreme symptoms of A-fib. However, if you’ve been diagnosed with A-fib, it’s important to be aware of the possibility of blood clots.

Symptoms of Blood Clots from Atrial Fibrillation


When clots are in your bloodstream, they can travel throughout your body. The symptoms you have depend on where the blood clot is in your body. For example, a blood clot that blocks blood flow to your brain can cause a stroke, damage to brain cells, or permanent damage to your brain. The clot can be life-threatening in some cases.

A blood clot isn’t the only potential sign of A-fib. Before a blood clot causes problems, it may cause other symptoms that are more easily identified. Common symptoms of A-fib include:

  • shortness of breath
  • dizziness
  • feeling faint or extreme fatigue
  • chest pain
  • general weakness
  • sweating
  • heart palpitations, or a racing heartbeat

Not everyone with A-fib experiences symptoms. It’s possible to have A-fib without knowing you have the condition. However, A-fib increases your risk of blood clots and stroke even if you don’t have symptoms. Strokes from A-fib often happen when blood pools in your heart and causes a clot that blocks blood flow to your brain. A stroke can cause more consequences if you have A-fib. It’s important to know if you have A-fib as early as possible.

Preventing Blood Clots from Atrial Fibrillation



Your doctor may prescribe blood thinners to help prevent blood clots from forming. Medications can also restore your heart’s normal rate and rhythm. Restoring your heart’s rhythm reduces your risk of blood pooling.


In some cases, your doctor may recommend procedures that treat A-fib, including catheter ablation and electrical cardioversion. These procedures change the design of your heart and correct its rhythm.

Treating Underlying Conditions

Treating underlying conditions that contribute to A-fib is also important. Other heart diseases increase your risk for blood clots from A-fib, including heart disease, infections, and heart defects. It’s important to address both A-fib and any conditions that may make the problem worse.

Diet and Lifestyle Changes

Healthy lifestyle choice can help you prevent A-fib. Regular exercise contributes to a healthy heart. This includes:

  • walking
  • running
  • swimming
  • biking

Maintaining a diet high in vitamin K and low in fats also lowers your risk of developing A-fib. Avoiding both smoking and excessive caffeine also helps protect your heart’s health. If you drink alcohol, you should restrict it to two drinks or less per day.

Types of Atrial Fibrillation

 Type 1

The two main types of A-fib are controlled and uncontrolled.

Controlled Atrial Fibrillation

Cardiac output is the amount of blood pumped out to your body. A-fib happens when the slowing of your heart’s ventricles lowers your cardiac output. Controlled A-fib usually results in a heart rate less than 100 beats per minute (BPM).

Uncontrolled Atrial Fibrillation

Uncontrolled A-fib happens when the slowing of your ventricles increases your cardiac rate above 100 BPM. Your heart is most controlled when you’re at rest and your cardiac output is around 100 BPM.

Atrial Fibrillation vs. Atrial Flutter

Atrial flutter affects your heart in similar ways as A-fib, but it’s not a type of A-fib. Atrial flutter happens when your heart’s upper chambers beat quickly but regularly while the lower chambers beat either regularly or irregularly. Atrial flutter is usually less harmful than atrial fibrillation. The risks of clot formation are much lower when you have atrial flutter.

Risk Factors

Risk Factors

Most cases of A-fib are caught during a routine electrocardiogram (EKG). This simple test monitors your heart’s electrical activity and can reveal irregularities.

Talk to your doctor if you’re concerned that any symptoms you’re having may be the result of A-fib. Your doctor may request an EKG to check for heart problems or refer you to a cardiologist, a doctor who specializes in treating heart conditions.

If you have A-fib, work with your doctor to do everything you can to lower your risk of complications such as blood clot and stroke. Avoid serious complications later by getting ahead of your symptoms before they become problematic. There are many steps you can take to prevent the consequences of A-fib. Be kind to your heart and choose a healthy lifestyle.

You asked, we answered

  • What types of exercises are best for someone with atrial fibrillation?- Anonymous
  • Low-impact exercises are traditionally better, such as walking, cycling, swimming, or even yoga. Listen to your body. Keeping a slow, steady pace is always best.

    - Mark R. LaFlamme, M.D.

Read This Next

Atrial Fibrillation: What’s My Prognosis?
Recurrent Venous Thromboembolism: Symptoms, Treatment, and More
What Does It Feel Like When You Have a Blood Clot?
Where Can Blood Clots Form?
Blood Clots After Surgery: Tips for Prevention