Atrial Fibrillation and Atrial Flutter

The main complications include the following:

In atrial fibrillation or atrial flutter, the atria do not empty completely into the ventricles with each beat. Over time, some blood inside the atria may stagnate, and blood clots may form. Pieces of the clot may break off, often shortly after atrial fibrillation converts back to normal rhythm—whether spontaneously or because of treatment. These pieces of clot may pass into the left ventricle, travel through the bloodstream (becoming emboli), and block a smaller artery. If pieces of a clot block an artery in the brain, a stroke Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction). Symptoms occur suddenly... read more results. Rarely, a stroke is the first sign of atrial fibrillation or atrial flutter.

When atrial fibrillation or atrial flutter causes the heart to beat too rapidly, the ventricles do not have enough time to fill completely with blood. Because they do not fill completely, the amount of blood pumped by the heart decreases. This decrease may cause the blood pressure to fall, and heart failure Heart Failure (HF) Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or... read more may occur.

Usually, the first step in treating atrial fibrillation or atrial flutter is to slow the beating of the ventricles so that the heart pumps blood more efficiently. Usually, drugs can slow the ventricle. Often, the first drug tried is a calcium channel blocker, such as diltiazem or verapamil, which may slow the conduction of impulses to the ventricles (see table ). A beta-blocker, such as propranolol or atenolol, may be used. For people who have heart failure, digoxin may be used.

Atrial fibrillation or atrial flutter may spontaneously convert to a normal rhythm. In some people, these arrhythmias must be actively converted to a normal rhythm (cardioversion Cardioversion-Defibrillation There are many causes of abnormal heart rhythms (arrhythmias). Some arrhythmias are harmless and do not need treatment. Sometimes arrhythmias stop on their own or with changes in lifestyle,... read more ). Such people include those in whom the atrial fibrillation or atrial flutter causes heart failure or other symptoms of low heart output.

Before restoring normal rhythm, because there is a risk that a blood clot will break off and cause a stroke during conversion, measures must be taken to prevent blood clots.

If the atrial fibrillation or atrial flutter has been present for more than 48 hours, doctors give an anticoagulant, such as warfarin, for 3 to 4 weeks before attempting conversion. Alternatively, doctors can give a short-acting anticoagulant, such as heparin, and do echocardiography. If echocardiography does not show a clot in the heart, the person can undergo conversion immediately. If the rhythm has clearly been present less than 48 hours, people do not need an anticoagulant before conversion. However, most people need an anticoagulant for at least 4 weeks after conversion.

Methods of conversion include

An electrical shock to the heart is the most effective approach. The electrical shock is synchronized to be given only at a certain point in the heart's electrical activity (synchronized cardioversion Cardioversion-Defibrillation There are many causes of abnormal heart rhythms (arrhythmias). Some arrhythmias are harmless and do not need treatment. Sometimes arrhythmias stop on their own or with changes in lifestyle,... read more ) so that it does not cause ventricular fibrillation. Cardioversion is effective in 75 to 90% of people.

Certain antiarrhythmic drugs (most commonly, amiodarone, flecainide, procainamide, propafenone, or sotalol—see table ) also may restore a normal rhythm. However, these drugs are effective in only about 50 to 60% of people and often cause side effects.

Conversion to a normal rhythm by any means becomes less likely the longer the arrhythmia has been present (especially after 6 months or more), the larger the atria become, and the more severe the underlying heart disorder becomes. When conversion is successful, the risk of recurrence is high, even if people are taking a drug to prevent recurrence (typically one of the same drugs used to convert the arrhythmia to a normal rhythm).

Rarely, when all other treatments of atrial fibrillation are ineffective, the atrioventricular node can be destroyed by an ablation procedure Destroying Abnormal Heart Tissue (Ablation) There are many causes of abnormal heart rhythms (arrhythmias). Some arrhythmias are harmless and do not need treatment. Sometimes arrhythmias stop on their own or with changes in lifestyle,... read more . Ablation is a process to kill a specific area of abnormal tissue using energy from radiofrequency waves, lasers, or electrical current, or by applying very cold temperatures. These are applied using a catheter inserted into the heart.

By destroying the AV node, this ablation procedure completely stops conduction from the atria to the ventricles. Thus, although the atria continue to fibrillate, the ventricular rate slows down. However, a permanent artificial pacemaker Artificial Pacemakers There are many causes of abnormal heart rhythms (arrhythmias). Some arrhythmias are harmless and do not need treatment. Sometimes arrhythmias stop on their own or with changes in lifestyle,... read more is required to activate the ventricles afterward.

Another type of ablation procedure for atrial fibrillation destroys atrial tissue near the pulmonary veins (pulmonary vein isolation). Pulmonary vein isolation spares the atrioventricular node and can stop the atrial fibrillation but is less often successful (60 to 80%), and the risk of serious complications is significant (1 to 5%). Accordingly, this procedure is often reserved for the best candidates (such as, younger people who have no significant heart disease like a heart valve disorder, people without other options such as those with atrial fibrillation that does not respond to drug therapy, or people with heart failure Heart Failure (HF) Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or... read more .

For people who have atrial flutter, ablation may be used to interrupt the flutter circuit in the atrium and permanently re-establish normal rhythm. This procedure is successful in about 90% of people.

Measures to prevent blood clots (and thus prevent stroke Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction). Symptoms occur suddenly... read more ) are necessary when atrial fibrillation or atrial flutter is converted back to normal rhythm. Most people also usually need such measures during long-term treatment. Doctors typically give an anticoagulant Anticoagulation Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or... read more such as warfarin, dabigatran, or a clotting factor Xa inhibitor (rivaroxaban, apixaban, or edoxaban). People who cannot be given an anticoagulant may be given aspirin, which also can help prevent stroke, but aspirin is not as effective as warfarin.

Otherwise healthy people who had only one episode of atrial fibrillation that converted to normal rhythm (spontaneously or with treatment) need anticoagulant treatment for only 4 weeks. People who had several episodes of atrial fibrillation or atrial flutter or who remain in such rhythms despite treatment should take a drug to prevent blood clots indefinitely.

Doctors use warfarin or other anticoagulants for people who have one or more risk factors for developing stroke. Such risk factors include

Some people without those risk factors are given aspirin, and some are not given any treatment to prevent strokes.

Even after atrial fibrillation or atrial flutter converts to normal rhythm, doctors usually continue anticoagulant treatment, often for the remainder of the person’s life. This anticoagulant treatment is needed because the arrhythmia may come back without the person being aware of it. Dangerous blood clots can form during these episodes.