Atrial Fibrillation & Flutter Common Questions

Atrial fibrillation is a heart rhythm disorder in which the electrical impulses that control muscle contractions in the upper chambers of the heart (atria) become rapid and chaotic. Atrial flutter is similar, but only a single electrical wave circulates very rapidly in the upper chambers. People with these conditions may experience a racing heartbeat and other symptoms. Below are some frequently asked questions about AF.

What is Atrial Fibrillation/Atrial Flutter (AF)?
AF occurs when the electrical signals that control muscle contractions in the upper chambers (atria) of the heart become rapid sometimes causing the heart to beat at a rate greater than 300 beats per minute. This may cause the heart muscle to spasm or quiver, so the atria cannot effectively pump blood to the lower chambers (ventricles). In atrial fibrillation, the heart beat often is irregular and chaotic. An irregular heartbeat usually is not a symptom of atrial flutter.

How Common is AF?
AF is the most common heart rhythm disorder. An estimated 2.2 million people in the United States have AF, and approximately 160,000 new cases are diagnosed every year.

Who is Most Likely to Develop AF?
AF is uncommon among young people, and the likelihood of developing the condition increases with age. After age 65, between 3 percent and 5 percent of people have AF. Approximately 9 percent of people age 80 or older have the condition.

What Causes AF?
In many people, there is no apparent cause for AF. These individuals have what is called "lone" or idiopathic AF. In others, AF may be related to other medical conditions, such as: coronary artery disease (CAD), thyroid disease, high blood pressure (hypertension), structural defects of the heart and its valves, lung disease and other medical conditions.

What Is the Function of the Atria?
The right atrium receives returning blood that has circulated through the body and the left atrium receives oxygenated blood from the lungs. The atria act as priming pumps to send the blood to the lower chambers (ventricles). The ventricles pump the blood out of the heart and back to the lungs and the body.

What are the different types of AF?
AF may occur from time-to-time (paroxysmal AF), or it may occur constantly (persistent or permanent AF).

How Serious is AF?
AF is usually not life-threatening if it is properly diagnosed and treated. In younger people who have no other disease that affects the heart, AF usually is not considered serious. In some people, however, AF increases the risk of stroke, congestive heart failure or cardiomyopathy. According to the Framingham Heart Study, people with AF have a 3 to 5 times greater risk of stroke, especially individuals who are older than 65, have already had a stroke, or have high blood pressure, diabetes or congestive heart failure. These risks can be reduced by the careful use of blood thinners such as coumadin

Sometimes, AF also can damage heart muscle, alter the normal electrical signals of the heart and change the patterns of contraction and relaxation of heart muscle. This is known as electrical remodeling.

What is the relationship between AF and stroke?
During an episode of AF, the muscle of the upper chambers of the heart does not contract as it normally does to force open the valve through which blood passes from the atrium to the ventricle. The valve opens passively, but some blood may not enter the ventricle as it should. Instead, it pools in parts of the atrium, increasing the risk that clots will form in the stagnant blood. Even small blood clots can cause problems if they leave the heart and are released into the general circulation. They may clog arteries in the body and disrupt the blood supply to vital organs. Stroke happens when a clot interrupts the blood supply to the brain.

How is Atrial Fibrillation Diagnosed?
The simplest way for your doctor to diagnose AF is a combination of feeling your pulse and recording an electrocardiogram (ECG). If your pulse is faster than 100 beats per minute and irregular, AF is suspected. The diagnosis is then confirmed with an ECG - a simple, painless test that records the electrical activity of the heart through electrodes that are pasted temporarily to the skin of the chest, arms and legs. An ECG often is performed in your doctor's office, using a machine that prints out a graph showing electrical activity of different parts of the heart.

Sometimes, the patient may be asked to wear a small portable device with electronic memory to record a series of ECGs over time. These devices include Holter monitors and event recorders. A Holter monitor runs continuously, and usually is worn for 24 to 48 hours. An event recorder is switched on by the patient to record an ECG whenever he or she senses an irregular heartbeat.

How is Atrial Fibrillation Treated?

To Prevent Stroke. Aspirin and warfarin (Coumadin®) are drugs that may be prescribed to prevent the formation of blood clots that can lead to stroke. These medications, called anticoagulants, must be carefully regulated so that the body maintains its ability to form clots that will stop bleeding in the event of injury. The decision to prescribe these medications - and which to prescribe - is based on patient age and risk factors. Warfarin usually is prescribed for patients who are over age 65, or who have had a prior stroke or have other health problems such as heart failure, coronary artery disease, diabetes or hypertension. Aspirin (or no medication) is the standard treatment for people under age 65 who do not have any risk factors that increase the likelihood they will develop blood clots associated with AF.

To Treat Arrhythmias. There are a number of short-term and long-term treatments aimed at preventing or controlling the abnormal heart rhythm associated with AF.

Short-Term Treatments:
Oral medications that slow the heart rate during AF include drugs such as beta blockers (metoprolol, atenolol, propranolol), calcium antagonists (verapamil, diltiazam) and digitalis. (digoxin) These slow the transmission of electrical signals from the atria to the ventricles.

Electrical Cardioversion. For most individuals with chronic AF or those whose symptoms are not improved with medications, the heart's normal rhythm can be restored by delivering a controlled electric shock to the heart. This breaks the pattern of abnormal electrical signals. This procedure is performed under careful medical supervision and short-acting sedatives are used so that patients do not feel any pain or discomfort.

Drug Cardioversion is when drugs such as ibutilide are given to restore the heart's normal rhythm.

Long-Term Treatments:
The goal of long-term treatment may be to maintain the heart's normal sinus rhythm and prevent future episodes of AF. Sometimes the goal is to control the heart rate. These treatments may include:
Oral medications: Medications to control heart rhythms are called "anti-arrhythmics". A number of different drugs with different characteristics may be used to convert or prevent AF. Antiarrhythmic drugs need to be tailored specifically to the individual patient. Unfortunately, medications are not always effective in controlling AF, or cannot be used in some patients because of undesirable side effects. When medications do not work or are not an option because of side effects, catheter ablation (CA) may be effective in some patients.
Catheter Ablation (CA): In this procedure, flexible, thin tubes (catheters) are introduced into blood vessels and directed into the heart under x-ray guidance. A burst of radiofrequency energy is delivered which destroys small areas of heart muscle that give rise to abnormal electrical signals, thus preventing the initiation of AF. When medications to not prevent AF and rapid heart rates remain difficult to control, CA may also be used to cut the electrical connection between the atria and ventricles. This requires implantation of a pacemaker and does not eliminate the need for blood thinners, but does restore a regular heart rhythm and many people feel much better after undergoing this procedure.
Atrial Pacemakers are devices permanently implanted under the skin to regulate the rhythm of the heart to reduce the frequency of paroxysmal AF in some patients, especially in those with slow rhythms, either because of abnormalities of their own pacemaker or as the result of medications. Low-energy internal atrial defibrillators (atrial ICDs) automatically (or on command) deliver a controlled electric shock to restore the heart's normal rhythm when they detect an episode of AF. In many patients a decision may be made to allow atrial fibrillation to persist. Thearapy is then focused on adequate rate control with medications and protection from the formation of blood clots as outlined above.