Atrial fibrillation is the most common form of irregular heartbeat (arrhythmia). Normally, your heart’s electrical system controls the rhythm at which your heart beats. See illustrations of the heart and its electrical system.
In atrial fibrillation, abnormal electrical impulses cause the upper chambers of the heart (atria) to fibrillate, or quiver, resulting in irregular and rapid beating of the ventricles, the heart’s main pump.
As a result, the heart pumps less efficiently, reducing blood flow to the body and to the heart muscle itself. For most people, this aspect in itself is usually not life-threatening.
However, people with atrial fibrillation are at increased risk for life-threatening strokes, especially if they are not taking anticoagulant medications. Inefficient pumping of the atria allows blood to pool and clot there. If these clots are pumped out of the heart and into the bloodstream, they can lodge in the brain’s blood vessels, resulting in stroke.
In addition, if the heart rate is fast and uncontrolled over a long period, this can damage the heart and lead to heart attack and heart failure.
Many people with atrial fibrillation do not notice that their heart is beating irregularly and may not have symptoms. Others may have symptoms such as weakness, shortness of breath, and heart palpitations or more serious problems such as fainting (syncope), stroke, or heart failure.
Because atrial fibrillation increases your risk for stroke and many people do not have symptoms, the American Heart Association recommends that everyone, particularly those age 55 or older, check their heartbeats once a month.
To learn how to check your pulse, see taking your pulse. If you notice your heartbeat does not have a regular rhythm, talk to your doctor.
The most common cause of atrial fibrillation is long-standing and uncontrolled high blood pressure. Other underlying heart diseases that cause atrial fibrillation include:
Excessive alcohol consumption, caffeine and stimulant drug use can also trigger atrial fibrillation.
It may also occur in people with otherwise normal hearts. This is known as lone atrial fibrillation.
In some people, atrial fibrillation returns to a normal rhythm on its own. About 50% of people with recent-onset of this condition return to a normal rhythm within 24 to 48 hours.
If a normal rhythm does not naturally return, your doctor will probably try to convert your heart rhythm to a normal rhythm (cardioversion) with medication or a low-voltage electrical shock.
When atrial fibrillation is long-standing, it is more difficult to convert to a normal rhythm (also called a normal sinus rhythm). When cardioversion is not an option or does not work, this condition persists and medications are given to control the heart rate and prevent stroke.
Antiarrhythmic medications may be used to return an irregular heartbeat (arrhythmia) to its normal rhythm, prevent the occurrence of an arrhythmia, or control the heartbeat during an arrhythmia. These drugs work mostly by stabilizing the heart muscle tissue or slowing the heart rate.
Examples of antiarrhythmic medications are:
Many of these medications have side effects and interactions with other medications.
A person taking any of these medications should be in good communication with his or her health professional.
However, for some people, antiarrhythmic medications may not be the preferred treatment.
In a recent study, called the AFFIRM trial, medications to slow the heart rate, such as beta-blockers, calcium channel blockers, and cardiac glycosides (digoxin), were found to be preferable to antiarrhythmic medications as first-line treatment for certain people with atrial fibrillation, specifically older people at risk for stroke who did not have severe symptoms.
Taking medications to slow your heart rate may leave you in atrial fibrillation, although most people tolerate an irregular heart rhythm if the rate is kept between 60 to 100 beats per minute. Furthermore, the study found that antiarrhythmic medications were expensive, often had side effects, and did not produce better results in this group of people.
Anticoagulant medications, such as heparin, warfarin, and aspirin, are used to reduce the risk of blood clot forming. Blood clots can cause problems in the brain (stroke), the heart (heart attack), or other organs in the body. Treatment with anticoagulants may be continued for the rest of your life.
If infection, hyperthyroidism, or heart failure is the cause of your atrial fibrillation, medications are used to control heart rate while the underlying disease is being treated.
In some people the heart rate remains rapid, because medication may either be ineffective or not tolerated. In these cases, a non-surgical procedure called radiofrequency catheter ablation may be done. If available, electrophysiology testing is first done to try to identify the source of the abnormal electrical signals.
If identified, radio frequency energy is used to destroy, or ablate, that tissue. If this does not cure atrial fibrillation or is not an option, then the AV node can be ablated, which blocks abnormal impulses and normal signals from the sinoatrial (SA) node from pacing the ventricles.
A permanent pacemaker is then implanted to regulate the heart rhythm. Anticoagulation therapy is still necessary in these cases.
An electrocardiogram, or EKG, is the best and simplest way to determine whether you have atrial fibrillation. An electrocardiogram is a tracing of the electrical activity of your heart. It is usually done along with a history and physical exam, lab tests, and a chest X-ray.
How you fare with atrial fibrillation depends most often on the underlying condition causing it and your symptoms. High blood pressure and other underlying heart diseases are common causes of this condition.
Seen mostly in people over 65, atrial fibrillation due to underlying heart disease is often the most complicated to treat. Initially, episodes of this condition typically come on suddenly and last a short time before subsiding on their own. This is called paroxysmal atrial fibrillation.
Over time, episodes of atrial fibrillation usually become longer and more frequent, and eventually the irregular heartbeat becomes persistent, meaning that it no longer resolves on its own. Your doctor may attempt to convert to a normal rhythm by a procedure called cardioversion, using either medication or electrical cardioversion. The longer this condition has been present, the less likely cardioversion will result in a lasting normal rhythm.
If cardioversion fails or atrial fibrillation returns, medications are used to control the heart rate, although this condition will persist. If you continue to have symptoms, antiarrhythmic medications may be given.
Many people are able to live full and active lives while being treated for atrial fibrillation. Others become short of breath and weak with normal physical activities and need further treatment, such as catheter ablation, a procedure used to destroy the atrioventricular (AV) node and other tissues, such as triggers in the pulmonary veins, that are responsible for an irregular heart rhythm.
When an underlying cause, such as hyperthyroidism, can be treated, atrial fibrillation usually goes away. Likewise, when severe infections are cured or caffeine or other stimulant use is discontinued, atrial fibrillation usually stops and the heart stays in a normal rhythm.
This condition frequently occurs after cardiac surgery and can increase the risk of complications, such as stroke. Treatment usually results in conversion to a normal rhythm within 6 weeks after leaving the hospital.
In rare cases, the underlying cause of this condition cannot be determined. Lone atrial fibrillation usually occurs in people under 65. It often stops on its own or it can be treated easily.
Lone atrial fibrillation progresses to permanent atrial fibrillation in about 20% of cases.