Atrial Fibrillation
How is it treated?
There are numerous ways to treat AF. The methods include reversing the underlying cause of the atrial fibrillation, slowing the heart rate with medications, or using medication or electrical shocks to correct the rhythm of the heart. Consideration should also be given to using medications that keep the blood from clotting in order to prevent strokes in patients with AF.
The most recent guidelines by the American College of Cardiology and the American Heart Association state that controlling heart rate is equally effective to controlling heart rhythm. Several large studies support the conclusion that heart rate control is better tolerated and may have better outcomes in certain people.
What?s the difference between rate and rhythm control? Rate control means lowering the heart rate to between 60 and 80 beats per minute when at rest and between 90 and 115 beats per minute during moderate exercise. The drugs most commonly used to control heart rate are non-dihydropyridine calcium channel blockers, beta-blockers, digoxin, and amiodarone.
Rhythm control means attempting to restore the regular beating pattern of the heart. There are multiple drugs used to change heart rhythm and most can only be used in certain situations and may require special follow-up with the doctor. The medications used to change heart rhythm are called anti-arrhythmics and include amiodarone, dofetilide, sotalol, flecanide, propafenone, dispyramide, procainamide, and quinidine. The table below lists which anti-arrhythmics are the most effective to treat AF in different patient populations
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If you have: |
Then your doctor may prescribe one of the following: |
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Heart failure
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Amiodarone, Dofetilide
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Coronary artery disease
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Sotalol, Amiodarone, Dofetilide
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High blood pressure
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Amiodarone
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Normal blood pressure
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Flecainide, Propafenone, Amiodarone
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AF that was not controlled with previous therapies
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Disopyramide, Procainamide, Quinidine
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Electronic cardioversion is another method used to restore normal heart rhythm. A strong electrical charge or ?shock? is applied through paddles to the heart ?resetting? the SA node and hopefully restoring normal rhythm. Cardioversion is used in patients who cannot take certain drugs used to change heart rhythm. It is generally considered more effective than using medication to correct the rhythm of the heart. This procedure requires a very short acting anesthetic before the procedure and is only done in the hospital. This method may be repeated up to three times if the abnormal rhythm returns.
In patients with recurrent AF (AF that returns in less than 12 months after previously successful therapy), surgery is an option. One surgical procedure is the destruction of the atrioventricular (AV) node. The AV node passes electrical impulses from the atria to the ventricles. Once the node is destroyed, a pacemaker is placed in the heart. Pacemakers are mechanical devices that maintain the heart's normal rhythm. Another procedure is the implantation of an atrial defibrillator. When the heart is beating irregularly, the defibrillator sends electrical shocks to the heart to bring it back to a normal rhythm. These surgeries all have separate risks and benefits which should be discussed with a cardiologist (a doctor specialized in treating heart diseases) before a decision is made. Most are minimally invasive and require only short hospital stays.
In addition to controlling rate or rhythm, special care must be taken to prevent thromboembolism (blood clot) and strokes in patients with AF. Stroke is by far the most devastating complication of AF. There are several effective stroke prevention strategies. The most common are the use of warfarin (Coumadin) or aspirin.
The choice of therapy is up to the cardiologist, but certain risk factors may dictate the need for one therapy over another based on American Heart Association clinical guidelines. Risk factors for strokes in patients with AF include previous stroke or transient ischemic attack (?mini-stroke?), high blood pressure, heart failure, diabetes, coronary artery disease, mitral stenosis (a condition in which the mitral valve in the heart is abnormally narrow), artificial heart valves, and thyrotoxicosis (a condition in which the thyroid gland excessively functions and causes rapid heart rate and high blood pressure). Those patients with one or more of these risk factors should be started on warfarin as opposed to aspirin.
Warfarin is an oral anticoagulant, and sometimes called a blood thinner because it prevents clot formation. If cardioversion, either with medicine or an electrical shock, is planned, the patient must be on warfarin. The warfarin dose is adjusted based on a blood test called the INR. The INR must be between 2 and 3 to do the cardioversion, unless the AF is very new. Once the heart is in normal rhythm, the warfarin can usually be discontinued after 1 month. However, warfarin may need to be continued long-term if the patient is considered to be at high risk for stroke.
If a patient does not have any risk factors for stroke, aspirin (also an inhibitor of clot formation) 325mg per day may be used.
Drug classes used to treat Atrial Fibrillation Anti-Arrhythmics Beta Blockers Calcium Channel Blockers Cardiac Glycosides Oral Anticoagulants Salicylates
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How is it treated?
