How Atrial Fibrillation Is Diagnosed

In contrast to the diagnostic puzzle posed by many medical conditions, there is little mystery to diagnosing atrial fibrillation. Making a firm diagnosis is simply a matter of seeing the arrhythmia on an electrocardiogram (ECG). Once atrial fibrillation has been diagnosed, the real work begins in determining any underlying cause that needs to be treated.

Senior woman checks her heart rate on smart watch taking a break
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Self Checks/At-Home Testing

Make note of any symptoms that could be related to atrial fibrillation—palpitations, easy fatiguability, shortness of breath, chest discomfort, or episodes of lightheadedness or passing out. Try to recall any events or behaviors that seem to bring on your symptoms, such as exercise, emotional upset, sleeping poorly, or drinking alcohol.

If you have access to heart rate monitor app or a fitness tracker that senses heart rate, you could use this to record what is happening during your symptom episodes. This might be of use to your healthcare provider during your examination. However, conclusions you might draw from any such information should not prevent you from getting immediate medical attention to have your condition assessed.

A Surprise Diagnosis

It is possible for you to have no discernible symptoms of AFib whatsoever. The arrhythmia may be detected as an unexpected “incidental finding” on an office ECG, or during a stress test or an ambulatory monitoring study that is being done for another reason.

Physical Examination

As a first step, your healthcare provider will perform a full medical evaluation to characterize your arrhythmia and its potential causes as fully as possible.

You will be asked about your medical history and any symptoms that might suggest underlying cardiovascular or lung disease. Be as thorough as possible when providing your answers. Atrial fibrillation is known to develop after cardiac surgery, so that history will be noted.

Don’t be surprised if your healthcare provider asks you more than once about alcohol. Atrial fibrillation can be triggered by alcohol ingestion—in some people, even small amounts can do it. Because alcohol is one of the few truly reversible causes of atrial fibrillation, it is important for your healthcare provider to assess this aspect of your history carefully.

Your healthcare provider will then perform a careful physical examination looking for any additional clues (for instance, the presence of hypertension). They should take special care to check for reversible causes of atrial fibrillation, since treating these conditions is likely to keep the arrhythmia from recurring. These include hyperthyroidism, pulmonary embolus, and pericarditis.

Labs and Tests

An electrocardiogram is the first test that will be done to assess heart palpitations and other signs of atrial fibrillation. If you are having atrial fibrillation when you first seek medical help, the diagnosis will become immediately apparent as soon as an ECG is performed.

On the other hand, you might have paroxysmal (intermittent) atrial fibrillation, with symptoms that come and go, and the ECG in the healthcare provider’s office may be normal. Here, ambulatory monitoring (wearing an ECG recorder for a few days or a few weeks) will eventually reveal the problem. The trick is to make sure ambulatory monitoring continues until at least one episode of symptoms is captured.

Additional tests will also be used to help your healthcare provider determine what's behind your AFib. For example:

  • Blood testing: In addition to standard blood testing (including a fasting blood sugar to look for signs of diabetes), it is important for your healthcare provider to get thyroid function tests. Especially in older people, thyroid problems can be present without any of the classic symptoms.
  • Stress test: A stress test is usually not necessary for the evaluation of atrial fibrillation, but may be helpful if your medical history or your symptoms suggest the presence of coronary artery disease.

Besides providing the diagnosis of atrial fibrillation, the ECG can also give important clues about the presence or absence of underlying heart disease.

Intermittent/Paroxysmal AFib
  • The problem is brand-new or only happens once in a while

  • You have a normal heart rate most of the time

  • Your atrial fibrillation episodes are infrequent or brief

Chronic/Persistent AFib
  • You have atrial fibrillation more often than not

  • Periods of normal heart rhythm are infrequent or short-lived


An echocardiogram (echo) should be done to evaluate the cardiac valves and chambers, looking again for signs of underlying heart disease. This is a non-invasive test that can be performed in the healthcare provider's office. It doesn't require any anesthesia or special preparation.

As with ultrasound imaging, gel is placed on your chest and small transducer is applied. It sends sound waves toward your heart, like sonar. These are processed by a computer and an image of your beating heart appears on the screen. You are often asked to change positions to see the heart from different angles.

It may also be necessary to do a transesophageal echocardiogram (TEE), in which the echo transducer is passed into the esophagus (swallowing tube) directly behind the heart. It is considered an invasive test and may be done in a laboratory or operating room.

You will need to fast for 12 hours prior to the test. It requires a mild intravenous sedative and numbing local anesthetic for the back of your throat to suppress your gag reflex. The TEE can be useful in looking for blood clots in the left atrium before performing a cardioversion.

Differential Diagnoses

Most people with palpitations have some type of cardiac arrhythmia. Besides atrial fibrillation, the most common causes are premature atrial complexes (PACs), premature ventricular complexes (PVCs), and episodes of supraventricular tachycardia (SVT). A more dangerous cause of palpitations is ventricular tachycardia.

People who have significant heart disease are the most at risk for life-threatening arrhythmias, making it especially important to identify the cause of their palpitations. You are more likely to have heart disease if you have risk factors including a family history of heart disease, smoking, high cholesterol, an unhealthy weight, or a sedentary lifestyle.

Symptoms that seem to be palpitations might be due to something other than a heart arrhythmia as well. The assessment might show that the cause is a musculoskeletal problem or a gastrointestinal disturbance—even something as simple as gas.

A Word From Verywell

Having palpitations and other symptoms of atrial fibrillation can be scary. You may still be worried when an ECG shows that you indeed have this condition. While it may point to heart or health problems and risk factors that need to be addressed, it is usually not a dangerous condition in itself. Once your healthcare provider gathers all of the information, you will begin discussing which treatments for atrial fibrillation will be best for you.

Frequently Asked Questions

  • Can I take my own pulse to monitor atrial fibrillation?

    Sometimes, yes. In fact, healthcare providers can sometimes diagnose atrial fibrillation from a stethoscope alone. If you have a fitness tracker or smartwatch, you can also use these to track your heart rate and rhythm. If you notice unusual heart rhythms, be sure to see your healthcare provider or seek emergency care.

  • When should I see a healthcare provider for symptoms of atrial fibrillation?

    While symptoms of atrial fibrillation may come and go, if you experience heart rhythm disturbances that last longer than a few minutes, make an appointment to see your healthcare provider right away. If you experience any of the signs of a stroke or heart attack, such as sudden severe headache, weakness in an arm, or facial drooping, call 911.

  • How do I know if I have atrial fibrillation?

    Afib may go unnoticed, since it doesn’t always cause symptoms. The only way to be sure you have it is to get regular medical checkups. Common signs to watch for include fatigue, an irregular heart rate or a faster heart rate than usual, and shortness of breath. If these symptoms are occurring, your healthcare provider can confirm a diagnosis of Afib with an electrocardiogram.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Atrial Fibrillation Fact Sheet.

  2. Page RL, Wilkinson WE, Clair WK, Mccarthy EA, Pritchett EL. Asymptomatic arrhythmias in patients with symptomatic paroxysmal atrial fibrillation and paroxysmal supraventricular tachycardia. Circulation. 1994;89(1):224-7. doi:10.1161/01.cir.89.1.224

  3. Selmer C, Olesen JB, Hansen ML, et al. The spectrum of thyroid disease and risk of new onset atrial fibrillation: a large population cohort study. BMJ. 2012;345:e7895. doi:10.1136/bmj.e7895

  4. Goswami KC, Yadav R, Rao MB, Bahl VK, Talwar KK, Manchanda SC. Clinical and echocardiographic predictors of left atrial clot and spontaneous echo contrast in patients with severe rheumatic mitral stenosis: a prospective study in 200 patients by transesophageal echocardiography. Int J Cardiol. 2000;73(3):273-9. doi:10.1016/S0167-5273(00)00235-7

  5. AF Association. Know your pulse.

Additional Reading

By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.