Atrial fibrillation is a type of irregular heart rhythm, known as arrhythmia. Early diagnosis helps reduce the risk of severe complications, such as stroke and heart failure.

Atrial fibrillation (A-fib) is the most common form of heart arrhythmia in the United States. To diagnose A-fib, doctors may perform several assessments, from physical examinations to ultrasound imaging.

In addition to looking for signs of A-fib, doctors may check for underlying conditions that can cause arrhythmia and any resulting complications.

Sometimes, a general practitioner will refer a person to a cardiologist, who is a specialist in heart disease.

In this article, we look at the procedures and tests that doctors use to confirm a diagnosis of A-fib and identify possible causes and complications of the condition.

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As an initial assessment, a doctor will ask a person about their medical history. This will include questions about A-fib symptoms and their frequency, and questions about other risk factors.

In addition, the doctor may ask about eating and exercise habits, alcohol consumption, and any tobacco or recreational drug use.

They may also ask about a family history of A-fib. This is because people who have relatives with A-fib may have an increased risk of developing the condition.

Answering these questions can help the doctor identify any potential signs of A-fib or another condition and assess the overall risk.

The clearest physical sign of A-fib is an irregular heart rhythm. As a result, the doctor will check how fast the heart is beating by taking the person’s pulse. They can also listen to the rhythm and rate of heartbeats with a stethoscope.

As part of the examination, the doctor will assess other physical markers that may indicate a problem with heart function. They may measure blood pressure, check for heart murmurs, and look for evidence of heart failure.

The doctor will also look for signs of health conditions that can cause or contribute to A-fib, such as hyperthyroidism, which is an overactive thyroid gland.

Learn more about hyperthyroidism here.

Following a physical assessment, doctors can perform tests to confirm an A-fib diagnosis.

To diagnose A-fib, find its most likely cause, and identify any complications, a doctor may order:

An electrocardiogram: An electrocardiogram (EKG) records the electrical activity of the heart. Doctors often use this to confirm initial pulse rate evaluations. When someone has A-fib, the EKG will identify an irregular rhythm. This means that heartbeats do not have a regular pattern.

Holter monitoring: A Holter monitor is a portable EKG monitor that a person wears to record their heart rhythm and rate, usually for 24–48 hours. It can help document A-fib that occurs intermittently or has no symptoms. The longer a person wears the monitor, the higher the sensitivity of detection.

Event recorder: A person may need to wear this heart rate and rhythm monitor for weeks or even months. It may record on its own, or the person may need to push a button to start recording when they experience symptoms. This is effective for people who have arrhythmia intermittently.

Echocardiogram: An echocardiogram uses sound waves to produce a moving picture of the heart. This can help doctors see any blockages within the heart, such as blood clots.

This test may involve moving a wand-like tool called a transducer around the outside of the chest. In this case, it is called a transthoracic echocardiograph.

To get a clearer image of the heart, the doctor may need a transesophageal echocardiograph, which involves inserting a device into the esophagus.

Some other tests that may help point to the causes or complications of A-fib include:

Blood tests: These can help identify potential causes of A-fib, such as hyperthyroidism, and other contributing health issues, such as blood clots, anemia, or problems with kidney function.

Chest X-ray: This can help a doctor see the heart and lungs. An X-ray can highlight any visible complications of A-fib, such as a buildup of fluid, or an infection that may be causing A-fib.

A stress or exercise test: The doctor may need to conduct an EKG while the person does physical activity, such as running on a treadmill. This can show how A-fib may be affecting the person’s physical capability.

Tilt-table test: If an EKG or Holter monitor do not reveal arrhythmia, but the person still experiences symptoms, such as fainting or dizziness, the doctor may request this test. It shows heart function and blood pressure while the person lies on a table that moves them from a prone to an upright position.

Electrophysiology: If a doctor diagnoses arrhythmia, they may recommend an electrophysiologic study. This involves threading a catheter through a blood vessel into the chambers of the heart. The catheter then stimulates the heart and records where any abnormal impulses originate from and how fast they are.

Once a doctor has determined what is causing the arrhythmia, they can recommend treatments to correct it.

A-fib can be serious, but several tests can confirm the diagnosis and help identify the cause and any complications.

A doctor will ask about a person’s individual and family medical histories and personal exercise and dietary habits. They will also perform a physical examination to check for signs and complications of A-fib, as well as any underlying conditions.

Further tests may be necessary to confirm a diagnosis. These can include an EKG, ultrasound imaging procedures, or an X-ray of the chest. A person may also need to wear a monitor that measures their heart rate and rhythm over an extended period.

Once a doctor has diagnosed A-fib, treatments can help correct it.