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What is atrial fibrillation?

Atrial fibrillation (AFib) is a type of cardiac arrhythmia, or irregular heartbeat. In a healthy heart, oxygen-rich blood moves from your lungs to the left upper chamber of your heart. The upper chambers are called your atria. Your atria pump the blood into the two lower chambers of your heart, known as your ventricles. Blood from your lungs is pumped from the left atrium into the left ventricle. The left ventricle pumps your blood around your body and back to the right atrium, the right ventricle, and then your lungs.

Electrical impulses allow each part of your heart to beat in rhythm with other parts. If you have AFib, your heart’s electrical signals become disorganized. This causes your heart’s atria to beat chaotically, preventing proper blood flow.

In some cases, AFib causes potentially life-threatening complications. Blood clots are one of the more common complications. AFib interferes with the flow of blood through your heart. This can cause blood to pool in your heart’s upper chambers, which can cause blood clots to form.

It’s possible to have AFib with no noticeable symptoms. If you do develop symptoms, they may include:

  • heart palpitations
  • racing heartbeat
  • chest pain
  • shortness of breath
  • dizziness
  • fatigue
  • weakness
  • sweating

Even if you don’t have noticeable symptoms, AFib can still increase your chance of blood clots in the upper heart chambers. If a blood clot forms, it can travel throughout your body. Your symptoms depend on where the blood clot gets lodged after it breaks off. The most common complication of blood clots in the heart related to AFib is stroke. Blood clots usually form in the left atrium. If they break off, they will move into the left ventricle and then into the arterial circulation. The anatomy of your arterial system places your brain in a direct path downstream where the clots can easily lodge.

If a blood clot blocks the flow of blood to your brain, it causes a stroke. Symptoms may include:

  • numbness or paralysis on one side of your body
  • trouble walking or coordinating your movements
  • problems speaking or understanding others
  • difficulty seeing
  • headache
  • slurred speech
  • difficulty swallowing
  • dizziness

If you notice any signs of stroke, get medical help immediately. Early diagnosis and treatment is essential.

Blood clots can travel to other areas of the body as well. They can cause tissue damage to other organs including the liver, spleen, bowel, and kidneys. Damage to the liver and spleen from these small blood clots usually goes unnoticed. If you have a clot travel to the bowel, you may experience abdominal pain, nausea, vomiting, blood in your stool, or fever. If a blood clot travels to a kidney, you may have back pain, painful urination, or blood in the urine. In either case, you should seek medical attention. The clots may be very small, however, and cause no symptoms.

Clots can also lodge in the small arteries of your fingers and toes. This can cause bluish spots or bluish discoloration of the tips of the affected digits and severe pain. It may even cause eventual loss of part of the digit as well.

Many cases of AFib are caught during a routine electrocardiogram (EKG). This is a simple test that your doctor can use to assess your heart’s electrical activity. It can help them spot irregularities, including AFib.

AFib isn’t always life-threatening. You can potentially go your entire life without experiencing complications from AFib. To lower your risk of complications, follow your doctor’s recommended treatment and management plan. This can help you prevent blood clots from forming.


If you’ve been diagnosed with AFib, your doctor might prescribe blood thinners to lower your risk of blood clots. They may also prescribe other medications to help restore your heart’s normal rate and rhythm.

Cardiac procedures

In some cases, your doctor may recommend electrical cardioversion to restore your heart’s rhythm. Your doctor will use paddles or patches to apply an electrical current to your chest.

Sometimes, your doctor may not be able to control your heart rate with medication. Atrial fibrillation tends cause your heart rate to be very high. Rate control medications usually help keep your rate normal but, occasionally, an adequate dose to keep your rate normal may also result in a very low heart rate. A low heart rate or fluctuating heart rate can occur without medications as well. This condition is known as tachy-brady syndrome. In this case, you may be a candidate for catheter ablation. During this procedure, your doctor will thread a thin catheter through one of the veins in your heart. Electricity is then used to destroy either the area that is firing too fast or the pathway that allows the electrical impulses to travel from the atria where the impulses originate to the ventricles.

Treating underlying conditions

Your doctor may also recommend treatment for underlying conditions that might be contributing to your AFib. For example, heart defects, heart disease, electrolyte abnormalities, drug and alcohol use and abuse, pulmonary emboli, thyroid problems, and infections can cause AFib and increase your risk of blood clots. Your recommended treatment plan will vary, depending on your specific diagnosis.

Diet and lifestyle changes

Healthy lifestyle choices can help you prevent AFib, other forms of heart disease, and the formation of blood clots. For example:

  • Get regular exercise, such as walking, running, biking, and swimming.
  • Eat a well-balanced diet, while limiting your intake of sodium, saturated fat, and cholesterol.
  • Restrict your consumption of caffeine and alcohol.
  • Avoid smoking.

It’s possible to have AFib without developing complications. But in some cases, it can cause blood clots to form. If left untreated, these blood clots can travel to other areas of the body and cause serious damage, with stroke being the most common and serious complication.

If you suspect you might have AFib or blood clots, contact your doctor. They can help diagnose your symptoms. They can also help you develop a treatment plan to manage your condition and lower your risk of complications.



Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
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