How Is Atrial Fibrillation Diagnosed?

Some people who have atrial fibrillation (AF) don't have symptoms. For these people, AF often is found during a physical exam or EKG (electrocardiogram) test done for another purpose. Other times, AF is diagnosed after a person goes to the doctor because of symptoms.

To understand why a person has AF and the best way to treat it, the doctor will want to find any immediate or underlying causes of the condition.

Doctors use several methods to diagnose AF, including taking medical and family histories, doing a physical exam, and doing several tests and procedures.

Specialists Involved

A primary care doctor often is involved in the initial diagnosis and treatment of AF. These doctors can include family practitioners and internists.

Doctors who specialize in the diagnosis and treatment of heart disease also may be involved, such as:

• Cardiologists. These are doctors who diagnose and treat heart diseases and conditions.
• Electrophysiologists. These are cardiologists who specialize in arrhythmias.

Medical and Family Histories

Your doctor will ask questions about your:

• Signs and symptoms. What symptoms are you having? Have you had palpitations? Are you dizzy or short of breath? Are your feet or ankles swollen (a possible sign of heart failure)? Do you have any chest pain?
• Medical history. This includes other health problems, such as a history of heart disease, high blood pressure, lung disease, diabetes, or thyroid problems.
• Family's medical history. Does anyone in your family have a history of AF? Has anyone in your family ever had heart disease or high blood pressure? Has anyone had thyroid problems? Are there other illnesses or health problems in your family?
• Health habits. Your doctor may ask whether you smoke or use alcohol or caffeine.

Physical Exam

Your doctor will do a complete cardiac exam, listening to the rate and rhythm of your heartbeat and taking your pulse and blood pressure reading. He or she will likely check to see whether you have any signs of heart muscle or valve problems. Your doctor will listen to your lungs to check for signs of heart failure.

Your doctor also will check for swelling in your legs or feet and look for an enlarged thyroid gland or other signs of hyperthyroidism (too much thyroid hormone).

Diagnostic Tests and Procedures

EKG

An EKG is a simple, painless test that records the heart's electrical activity. It's the most useful test for diagnosing AF.

An EKG shows how fast your heart is beating and its rhythm (steady or irregular). It also records the strength and timing of electrical signals as they pass through each part of your heart.

A standard EKG only records the heartbeat for a few seconds. It won't detect an AF episode that doesn't happen during the test. To diagnose paroxysmal AF, your doctor may ask you to wear a portable EKG monitor that can record your heartbeat for longer periods.

The two most common types of portable EKGs are Holter and event monitors.

Holter and Event Monitors

 A Holter monitor records the heart's electrical activity for a full 24- or 48-hour period. You wear small patches called electrodes on your chest. These patches are connected by wires to a small, portable recorder. The recorder can be clipped to a belt, kept in a pocket, or hung around your neck.

You wear the Holter monitor while you do your normal daily activities. This allows the monitor to record your heart for a longer time than a standard EKG.

An event monitor is similar to a Holter monitor. You wear an event monitor while doing your normal activities. However, an event monitor only records your heart's electrical activity at certain times while you're wearing it.

For many event monitors, you push a button to start the monitor when you feel symptoms. Other event monitors start automatically when they sense abnormal heart rhythms.

You might wear an event monitor for 1 to 2 months, or as long as it takes to get a recording of your heart during symptoms.

Stress Test

Some heart problems are easier to diagnose when your heart is working hard and beating fast. During stress testing, you exercise (or are given medicine if you're unable to exercise) to make your heart work hard and beat fast while heart tests are done.

Echocardiography

Echocardiography (echo) uses sound waves to create a moving picture of your heart. The test provides information about the size and shape of your heart and how well your heart chambers and valves are working.

Echo also can identify areas of poor blood flow to the heart, areas of heart muscle that aren't contracting normally, and previous injury to the heart muscle caused by poor blood flow.

This test is sometimes called transthoracic (trans-thor-AS-ik) echocardiography. It's painless and noninvasive (no instruments are inserted into the body). The test is done by placing a device called a transducer on your chest. The device sends special sound waves through your chest wall to your heart.

The sound waves bounce off the structures of your heart, and a computer converts them into pictures on a screen.

Transesophageal Echocardiography

Transesophageal (trans-e-SOF-ah-ge-al) echo, or TEE, takes pictures of your heart through the esophagus (the passage leading from your mouth to your stomach).

The atria are deep in your chest and often can't be seen very well using transthoracic echo. Your doctor can see the atria much better using TEE.

During this test, the transducer is attached to the end of a flexible tube that's guided down your throat and into your esophagus. You'll probably be given medicine to help you relax during the procedure. TEE is used to detect blood clots that may be developing in the atria because of AF.

Chest X Ray

A chest x ray is a painless test that creates pictures of the structures in your chest, such as your heart and lungs. This test can show fluid buildup in the lungs and other complications of AF.

Blood Tests

Blood tests check the level of thyroid hormone and the balance of your body's electrolytes. Electrolytes are minerals that help maintain fluid levels and acid-base balance in the body. They're essential for normal health and functioning of your body's cells and organs.