Treatment for Atrial Fibrillation
Treatment of atrial fibrillation is complex and depends on whether the patient is currently experiencing symptoms, how long the patient has been in atrial fibrillation, the overall health of the patient, and the size and function of the heart's chambers.
Treatment in Stable Patients with Atrial Fibrillation
In stable patients, several general approaches may be taken. Those who are experiencing palpitations can be treated with certain medications that "slow" conduction of electrical impulses through the AV node and down into the ventricles.
Such medications include the following:
- Beta-blockers slow the heart rate. Several in use include: atenolol (Tenormin®), bisoprolol (Zebeta®), carvedilol (Coreg®), metoprolol (Lopressor®, Toprol XL®), nadolol (Corgard®), propranolol (Inderal®, Inderal® LA), and timolol (Blockadren®). These medications may initially be given intravenously. Long-term, they are usually taken in pill form once or twice a day.
- Calcium channel blockers have multiple effects on the heart. Two of these agents can be used to slow the heart rate in patients with atrial fibrillation: diltiazem (Cardizem®) and verapamil (Calan®, Calan SR®, Covera® HS, Isoptin®, Isoptin SR®, Veralan®). There are long-acting forms available that can be taken only once or twice a day.
- Digoxin (Lanoxin®) is often used to treat patients with heart failure, since it can stimulate the left ventricle to contract and pump blood a little more vigorously. Digoxin also slows electrical conduction through the AV node and can thus decrease the rate at which electrical impulses are conducted from the atria to the ventricles.
In July 2009, the U.S. Food and Drug Administration (FDA) approved dronedarone (Multaq®) to maintain normal heart rhythm in patients with atrial fibrillation. This drug can be used in stable patients who have returned to normal heart rhythms and patients who will undergo cardioversion to restore sinus rhythm. Dronedarone should not be used in patients with severe heart failure and can cause serious reactions and death in these patients. This medication is labeled with a black box warning. Side effects include fatigue, gastrointestinal (GI) problems (e.g., nausea, vomiting, diarrhea), and weakness.
Blood Thinners to Treat Atrial Fibrillation
Patients at risk for developing a blood clot in the left atrium are usually treated with blood thinners. Those who may already have a blood clot in the left atrium can be treated with blood thinners that help prevent the formation of more blood clots and allow the body to dissolve any formed blood clot. These patients usually receive heparin when admitted to the hospital.
The older form of heparin, unfractionated heparin, is usually administered via continuous intravenous infusion, and frequent blood tests (PPT, prothrombin-proconvertin test) are performed to monitor how "thin" the heparin is making the blood. Some doctors use one of the newer heparin preparations, low-molecular-weight heparin, to thin the blood. These preparations are injected in the skin (usually in the abdomen) twice a day, and repeated monitoring is not required. Some doctors may use these medications after discharge from the hospital. Such medications include enoxaparin (Lovenox®), dalteparin (Fragmin®), and nadroparin (Fraxiparin®)
Patients who require long-term "blood thinning" are treated with the medication warfarin (Coumadin®). Patients treated long term with warfarin require periodic monitoring with an INR test of the blood to assess if the blood is "thinned" to the correct degree. In patients with atrial fibrillation, most doctors aim for an INR value in the range of 2.03.0.
In February 2009, the U.S. Food and Drug Administration (FDA) approved ablation catheters to treat atrial fibrillation that does not respond to medication. In this procedure, a thin tube (catheter) is threaded into the heart to destroy targeted areas of tissue and block irregular impulses that cause atrial fibrillation. Ablation catheters also are approved to treat other types of arrhythmia. The long-term effects of this treatment are not yet known and remain under investigation.
Cardioversion through Medication
Although long-term treatment with warfarin may decrease the chances of having a stroke, it is generally felt that a more ideal approach to prevent stroke is to try to "convert" the heart rhythm from atrial fibrillation back into sinus rhythm. Not every patient can be successfully converted back into sinus rhythm. These patients include those who have been in atrial fibrillation for a long period of time and those who are found to have very enlarged (dilated) atria.
Patients can be converted into sinus rhythm through the administration of certain medications or by electrically "shocking" the heart. One of the newer medicines frequently being used to try to convert atrial fibrillation back into sinus rhythm is called ibutilide (Corvert®). This medication is administered intravenously for 10 minutes. If necessary, a second ten-minute infusion of the medication can be administered. Ibutilide is successful in converting selected patients with atrial fibrillation into sinus rhythm in approximately 6070% of cases. Ibutilide is associated with a small risk for causing other abnormal heart rhythms, and patients treated with ibutilide must be monitored for several hours after administration of the medication.
Many other medications are also used to try to chemically convert atrial fibrillation back into normal sinus rhythm. These include the following:
- Amiodarone (Cordarone®)
- Disopyramide (Norpace®)
- Flecainide (Tambocor®)
- Procainamide (Procanbid®, Pronestyl®)
- Propafenone (Rhythmol®)
- Quinidine (Quinaglute®, Quinidex®)
- Sotalol (Betapace®)