Atrial Fibrillation

What is Atrial Fibrillation?

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 a 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.

Atrial Fibrillation Symptoms

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.

Atrial Fibrillation Causes

The most common cause of atrial fibrillation is long-standing and uncontrolled high blood pressure. Other underlying heart diseases that cause atrial fibrillation include:

• Heart valve disease, especially of the mitral valve.
• Coronary artery disease (CAD) with impaired blood flow to the heart muscle (ischemia).
• Cardiomyopathy ( cardiac muscle disease) with the weakened heart muscle.

This condition may be caused by other medical conditions, such as hyperthyroidism, chronic obstructive pulmonary disease (COPD), and pneumonia.

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.

Atrial Fibrillation Treatment

For certain individuals, atrial fibrillation can return to a normal state by itself. 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.

Various antiarrhythmic drugs can be utilized to normalize an irregular heartbeat, stop future arrhythmia or maintain the heart rate during an arrhythmia. These drugs work mostly by stabilizing the heart muscle tissue or slowing the heart rate.

Examples of antiarrhythmic medications are:

• Ibutilide (Corvert).
• Amiodarone (such as Cordarone or Pacerone).
• Flecainide (Tambocor).
• Sotalol (Betapace AF).
• Procainamide (Procanbid).
• Propafenone (Rythmol).
• Quinidine (such as Quinidex).
• Disopyramide (Norpace).
• Dofetilide (Tikosyn).

Many of these medications have side effects and interactions with other medications.

It is highly recommended for anyone taking medication maintain open communication with their healthcare practitioner to ensure proper health.

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 clots 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 your heart rate while the underlying disease is being treated.

In some people, the heart rate remains rapid, because the 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.