Tests for Atrial Fibrillation

by Gerald Couzens

Symptoms of atrial fibrillation vary. It may be detected as an incidental finding during a physical examination or test that has been ordered for some other reason. Palpitations are a common symptom, and if you experience them, or other things such as shortness of breath, lightheadedness, dizziness, or chest pain, make an appointment with your doctor.

Electrophysiologist reviewing ECG with patient.


If atrial fibrillation is present on your electrocardiogram or if your history suggests AFib, your doctor may then refer you to an electrophysiologist (cardiologists who specialize in the heart’s electrical system) for further testing and/or treatment. These tests may include one or more of the following:

EKG monitor display

Electrocardiogram (ECG)

An electrocardiogram (ECG) is a simple test that traces the electrical activity of your heart. During an ECG, you lie flat on a table, connected to an ECG machine with wires taped to your chest, arms, and legs. The test is painless and takes a few minutes. The ECG produces a printout that doctors can examine to diagnose arrhythmias or other types of heart disease. When you have AFib, the atria produce a signature set of wiggles in the tracing, and the ventricular rate is typically irregular.

Holter monitor hooked up to man.

Holter monitoring: part 1

Holter monitoring is a continuous ECG recording—usually for 24 to 48 hours—while you go about your normal daily activities. It is useful to detect arrhythmias that may not occur during a resting ECG. During Holter monitoring, wires are connected to your chest and attached to a small recording device that you carry with you.

Doctor reviewing cardiogram chart.

Holter monitoring: part 2

If you experience any symptoms, you are asked to push a button and record your symptoms so that your heart rhythm at the time of your symptoms can be determined. An arrhythmia specialist will analyze the electrical recordings to determine what your actual heart rhythm was at the time that you were experiencing your symptoms and whether any asymptomatic abnormal heart rhythms occurred while you were wearing the Holter monitor.

Doctor reviewing event monitor read out on tablet

Event monitor: part 1

An event monitor, similar to a Holter monitor, does not record the heart rhythm continuously. Event monitors only record the heart rhythm when an abnormally fast or slow heartbeat occurs or when you activate them. An event monitor is used for a few months, during which you are instructed to trigger the device if symptoms occur. The ECG tracing can be transmitted over the phone to a monitoring station that will analyze the recording and send it to your arrhythmia specialist.

Technology has provided ECG tracking that can be saved to cell phone

Event monitor: part 2

Recently several new devices have appeared on the market that allow single lead ECGs to be obtained using a smart phone (AliveCor and ECG Check). Unlike standard event monitors, which are used by patients for 7 to 30 days and then returned to the monitoring company or hospital, these new devices can be purchased with a cost of less than $200 and are available for patients to use indefinitely. The ECG tracing, once recorded, can be transmitted to a physician via email or as a text message.

Doctor reading printed version of ECG from implantable device.

Implantable monitor: part 1

The implantable monitor is a device that is inserted under the skin and functions like an event monitor. The device is typically recommended for patients who have passing-out spells every three to 12 months. It is used to both detect AFib and determine the amount of AFib that a patient is having. They also note the amount of time a patient is in atrial fibrillation. Recent studies have shown that these devices identify AFib in a significant proportion of patients who have an unexplained stroke.

Implantable monitors are so small can now be injected

Implantable monitor: part 2

The technique involved for inserting these devices has recently been simplified. The latest models are about the size of an AAA battery. Rather than requiring insertion through an incision (as a pacemaker does), the monitor is injected under the skin—avoiding the need for a large incision. Also in contrast to a pacemaker, no wires need to be placed in the heart, and the insertion is performed on an outpatient basis.

Doctors performing exercise stress test on young man.

Exercise stress test

Some arrhythmias only occur while a patient is exercising. Because of this, your doctor may recommend an exercise stress test. During this test, you briskly walk or jog on a treadmill while hooked up to an ECG machine. This allows your arrhythmia specialist to determine if you are experiencing any arrhythmias while exercising and determine if you have evidence of a blocked heart artery.

Doctor performing echocardiography on man

Echocardiogram: part 1

An echocardiogram is a noninvasive, painless test that allows cardiologists to see if your heart is functioning normally or if it is enlarged or weakened or has a damaged valve. Ultrasound waves are directed through the chest to the heart. The echoes of the sound waves are processed and used to produce images of the heart.

Doppler echocardiography display

Echocardiogram: part 2

Additionally, a transesophageal echocardiogram (TEE) may be performed by having you swallow the ultrasound probe (following numbing medication to the throat and appropriate sedation). The TEE provides close-up images of the heart from the esophagus. This technique is an excellent way to search for blood clots in the atria. Your physician may request that you have a TEE prior to an electrical cardioversion or catheter ablation.

CT image of heart

CT scan

Computed tomography (CT) scanning is performed by taking high-resolution X-ray images using a multislice scanner. This advanced imaging can detect coronary artery disease, evaluate congenital heart disease, and may be used to evaluate a patient’s heart prior to a complex catheter ablation procedure.

woman about to get MRI

Magnetic Resonance Imaging

Cardiac magnetic resonance imaging (MRI) is a painless means of evaluating the heart’s structure and function. It can sometimes detect rare heart conditions (such as arrhythmogenic right ventricular dysplasia and cardiac sarcoidosis) and involves no radiation. In the past, MRI was not allowed in patients with implanted cardiac pacemakers and defibrillators—but due to efforts of several physicians and researchers, MRI can now be safely performed in many patients with implanted cardiac devices.

Large bore IV catheter on ECG printout

Electrophysiology study: part 1

Some arrhythmias are difficult to diagnose and may require an electrophysiology (EP) study. An EP study is often used to evaluate patients who have “fainted” or have experienced an abnormal rapid heart rhythm. This test may be recommended for patients even if they are not experiencing symptoms. In other cases, patients with an inherited cardiac condition may undergo an EP study as part of their risk assessment. In these cases, the EP study may indicate the need for preventive treatment.

Electrophysiologist looking at heart Xray

Electrophysiology study: part 2

In an EP study, an electrophysiologist inserts several intravenous (IV) lines into large veins. The electrophysiologist then passes several electrical catheters through the IVs and guides them into the heart using X-ray imaging. This allows the electrophysiologist to examine the electrical activity inside your heart to determine if and why the rhythm is abnormal. Once that is known, your physician can prescribe the most effective treatment.

Gerald Couzens
Meet Our Writer
Gerald Couzens

Gerald Secor Couzens is the author and coauthor of more than two dozen books about health and medical topics, specializing in prostate health and memory disorders. He was the co-creator and managing editor of The Johns Hopkins Prostate Bulletin for more than 20 years.