How Atrial Fibrillation Is Diagnosed

ECG output
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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.

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 doctor during your examination. However, any such notes don't replace getting immediate medical attention to have your condition assessed.

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 doctor’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.

It is even possible for you to have no discernible symptoms whatsoever, and 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 other reasons. But one way or another, diagnosing atrial fibrillation is a matter of capturing the arrhythmia on an ECG.

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

You will need to be thorough in telling your doctor about your symptoms and medical history. Your doctor will ask you about any symptoms that might suggest underlying cardiovascular or lung disease, and will perform a careful physical examination looking for any additional clues (for instance, the presence of hypertension). Your doctor should take special care to check for reversible causes of atrial fibrillation, since treating these conditions is likely to keep the arrhythmia from recurring. Reversible causes include hyperthyroidism, pulmonary embolus, pericarditis, and recent surgical procedures.

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

Blood testing: In addition to standard blood testing (including a fasting blood sugar to look for signs of diabetes), it is important for your doctor to get thyroid function tests. Especially in older people, thyroid problems can be present without any of the classic symptoms.

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

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.

Imaging

An echocardiogram 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 doctor'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. The imaging procedure lasts for 30 to 60 minutes.

It may also be necessary to do a transesophageal echocardiogram (a 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 at 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, being overweight, 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, such as gas.

If the diagnosis is atrial fibrillation, it may be labeled as one of several types. Unfortunately, there are several classification systems, which can be confusing. It is useful to lump the types of atrial fibrillation into only two types:

  • New onset or intermittent atrial fibrillation. If this is a brand-new problem for you or it only happens once in a while, it may be called intermittent atrial fibrillation or paroxysmal atrial fibrillation. You have a normal heart rate most of the time and only brief or infrequent atrial fibrillation episodes.
  • Chronic or persistent atrial fibrillation. In this type, you have atrial fibrillation more often than not, with periods of normal heart rhythm being infrequent or short-lived.

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 doctor gathers all of the information, you will begin discussing which treatments for atrial fibrillation will be best for you.

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