An electrocardiogram (EKG, ECG) is the best and simplest way to determine whether you have atrial fibrillation. An electrocardiogram is a recording of the electrical activity of your heart. It is usually done along with a medical history and physical exam. During your exam, your doctor will take your blood pressure to determine whether you have high blood pressure. Your doctor will also listen to your heart to see if you have a heart murmur.

If your doctor suspects that you have atrial fibrillation that comes and goes, he or she may ask you to use a device to record your heart rhythm on a continuous basis. This is referred to by several names, including ambulatory electrocardiogram, ambulatory EKG, Holter monitoring, 24-hour EKG, or cardiac event monitoring.

Your doctor may do more tests to see whether you have damage to your heart or heart valves. An exercise electrocardiogram, also called a stress test, will help your doctor see whether you have coronary artery disease. An echocardiogram gives your doctor a lot of information about your heart. It can show whether your heart valves are damaged, how well your heart is pumping, and whether you have heart failure or have had a heart attack.

You may also have a blood test to check for hyperthyroidism. Hyperthyroidism develops when the thyroid gland makes too much thyroid hormone.

You may get an X-ray if your exams show that you might have heart failure or a problem in your lungs, such as pneumonia.

If you take anticoagulant medications for atrial fibrillation, you will need to have frequent blood tests to monitor how long it takes for your blood to clot (prothrombin time).