Atrial fibrillation: Diagnosis and testing

A doctor may perform one or more tests to diagnose atrial fibrillation (A-fib).

The doctor will look for signs of A-fib as well as any underlying conditions that might be causing arrhythmia and possible complications.

Sometimes a doctor will refer someone to a cardiologist, who is a specialist in heart disease.

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

Medical history

Firstly, a doctor will ask an individual about their medical history to determine whether they have any risk factors for A-fib.

They will ask about eating habits, exercise routine, whether a person smokes tobacco or uses illicit drugs, and how often they drink alcohol.

They will also ask if there is a family history of A-fib, as people with a family member who has the disorder have an increased risk of having A-fib themselves.

The medical history might help a doctor identify whether a person has any potential signs of A-fib, or symptoms of other conditions that could be causing A-fib.

Holter monitoring: This is a portable ECG monitor that a person wears to record their heart rhythm and rate over a more extended period while they carry out their daily activities. A person usually wears it for 24 to 48 hours. It is an effective way to document A-fib that occurs intermittently or has no symptoms.

Event recorder: Similar to a Holter monitor, a person wears an event recorder for weeks or even months. The individual wearing the monitor pushes a button to start recording whenever they experience symptoms.

This allows the doctor to examine the heart rate and rhythm when the symptoms occur and make an accurate diagnosis. This is an effective test for someone who only has the arrhythmia intermittently. However, a person must experience symptoms to know when to start recording, which is not always the case.

Echocardiogram: This test uses a device called a transducer that sends sound waves to produce a moving picture of the heart, helping to highlight any blockages, such as blood clots. When a doctor places the transducer on the outside of the chest, it is called a transthoracic echocardiograph (TTE).

If the transducer sits on a scope that a doctor then inserts into the esophagus, it is known as a transesophageal echocardiograph (TEE). A TEE produces a clearer image.

Some other tests that look for causes or complications of A-fib include:

Blood tests: These help identify potential causes of A-fib, such as hyperthyroidism. They can also highlight whether a person has other conditions that may affect A-fib, such as anemia or problems with kidney function.

Chest X-Ray: This creates an image of the chest, including the heart and lungs. An X-ray can highlight whether a person has any heart problems, such as heart failure that has caused fluid to build up in the lungs or enlarged the heart.

A stress or exercise test: The doctor conducts an ECG while the person engages in a physical activity, such as running on a treadmill. This test can show if A-fib is reducing blood supply to the heart.

Tilt-table test: A doctor may perform a tilt-table test if an ECG or Holter monitor do not reveal arrhythmia but the person still experiences symptoms, such as fainting or dizziness. The test checks a person’s heart function and blood pressure as the table moves them from a prone to an upright position.

If the test shows low blood pressure changes when a person is in an upright position, this may indicate that the brain is not receiving enough blood.

Electrophysiology: If a doctor diagnoses a person with arrhythmia, they may recommend an electrophysiologic test.

This is an invasive test that involves threading a catheter through a blood vessel into the chambers of the heart. The catheter stimulates the heart and records where the abnormal impulses come from, how fast they are, and which important conduction pathways they bypass.

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


A-fib can lead to serious complications, but several tests are available to confirm the diagnosis and detect complications.

A doctor will ask about a person’s medical history, including exercise routine and diet. They will also perform a physical examination, checking for signs and complications of both A-fib and any underlying conditions.

They might also perform several tests, including an ECG, take an X-ray of the chest, measure heart activity during exercise, or provide a take-home device to measure heart rate and rhythm over an extended period.

Once a doctor has diagnosed arrhythmia, treatments are available to try to stop it.


Does A-fib ever go undetected after visiting a doctor for a diagnosis


A doctor should be able to detect A-fib when they listen to your heart or take your pulse because they can hear and feel the irregular heartbeat.

In the unlikely event that a doctor orders an electrocardiogram (ECG) or echocardiogram without listening to your heart, these tests would pick up any signs of A-fib.

A doctor cannot identify A-fib if they do not check your heart or pulse. If you experience any symptoms of potential A-fib, such as a fast heartbeat, dizziness, confusion, or chest pains during activity, your doctor will check your heart or pulse.

A doctor will not automatically check your heart if you go to see them for something unrelated to your heart, such as a mild skin rash. This means A-fib could remain undetected.

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