Atrial Fibrillation Part I
Hector Fontanet, MD, FACC
August 5, 2005

Atrial fibrillation (a quivering of the upper chambers of the heart) is the most common form of irregular heart rhythm. Over two million Americans have it. It is present in 6% of our population over the age of 65 and 10% in the population over the age of 80. Studies done in other developed nations have similar percentages ( www.affacts.org ). This abnormal rhythm may cause no symptoms. Some patients can live with the condition for years before symptoms become uncomfortable or they are diagnosed on routine exam. For others, an awareness of rapid heart beats, shortness of breath, palpitations, dizziness and fatigue can be bothersome. Atrial fibrillation can be caused by acute isolated events and underlying cardiac disease but may also occur in patients without any structural heart disease.

For many patients, atrial fibrillation can be bothersome, but pose minimal or no medical risk. However, for patients with coronary artery disease, Diabetes Mellitus or high blood pressure, atrial fibrillation can be dangerous. It can lead to tachycardia-induced cardiomyopathy, heart failure and stroke (the most serious clinical consequence of atrial fibrillation). For this reason, proper diagnosis of atrial fibrillation by detailed medical history and physical examination as well as EKG and/or holter monitoring is necessary. If the condition is confirmed, further diagnostic testing (echocardiogram, stress testing, and in rare instances cardiac catheterization) will be performed to determine if there is an underlying cardiac condition that is causing atrial fibrillation and a plan course of treatment.

In some cases, emergency treatment for atrial fibrillation is necessary to convert the heart back to a normal rhythm by the use of IV medications or electric cardioversion. Long-term treatment options vary depending upon the underlying cause of the abnormal heart rhythm. Treatment includes restoring and maintaining normal heart rhythm or controlling heart rate. In most cases, in addition to other treatment options, patients will be treated with a blood thinner (Coumadin or Warfarin) to reduce the risk of stroke.

The AFFIRM Trial (Analysis of cause-specific mortality in the Atrial Fibrillation Follow-up Investigation of Rhythm Management) compared the two treatment strategies (rhythm and rate control) in patients who are at high risk of stroke. Though the outcomes did not show that rhythm control offered any advantage over rate control with respect to survival, it did show that in each treatment arm the rates of stroke were associated to the discontinuation of anticoagulation therapy or subtherapeutic levels of anticoagulation ( www.NEJM.org ).

Your heart specialist will be best suited to establish the etiology of the rhythm disturbance and discuss treatment strategies with you. In nearly all patients prevention of stroke with anticoagulation will be necessary. However, controlling the heart rate or restoring heart rhythm to normal is a choice that requires careful consideration of the risks and benefits to each individual patient. On our next article, we will discuss specific treatment options to restore normal rhythm.

Sources:
New England Journal of Medicine
American Heart Association
Heart Rhythm Society
Atrial Fibrillation Foundation

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Atrial Fibrillation Part II
Hector Fontanet, M.D., FACC
Marie Cheine, Medical Writer
August 26, 2005

In our last article, we discussed atrial fibrillation, the most common form of irregular heart rhythm. The goals of treatment for atrial fibrillation are prevention of stroke, control of heart rate and restoration of normal rhythm. As previously reported, the prevention of stroke in nearly all patients with atrial fibrillation will be necessary. This is carried out by the anticoagulation (blood thinning) with Coumadin® or Warfarin. It has been shown in clinical trials that treatment with aspirin is not sufficient to prevent stroke in this class of patients. Common medications for rate control include calcium channel blockers, beta-blockers and digoxin. Although this group of medications is effective in controlling the heart rate they are not usually effective in restoring normal heart rhythm. Medications that convert and maintain normal rhythm are called antiarrhythmics. Long term options for treatment are dependent upon the underlying cause (etiology) of each individual case.

Based on the results recently learned from various clinical trials, most asymptomatic patients will be best managed with rate control and anticoagulation only, avoiding potential side effects of antiarrhythmics. However, some patients remain symptomatic after rate is controlled. For these patients, or patients who have underlying heart disease, the use of antiarrhythmics has advantages, most importantly the improvement of quality of life, improving heart function in patients with heart failure and potentially allowing the discontinuation of anticoagulation therapy.

Antiarrhythmics, nevertheless, are a complex class of medications and carry risk and potential side effects. The most effective medication in this class is Amiodarone, which works by slowing nerve impulses in the heart and acting directly on the heart cells to synchronize the electrical impulses. These medications should be used judiciously and patients must be closely monitored while using them. In some cases, these medications can cause life threatening rhythm disturbances in patients with certain heart conditions. For this reason, your doctor may elect to start this type of medication in the hospital under careful observation.

In cases where symptoms or side effects remain intolerable or a patient fails medical therapy, other therapies such as electrical cardioversion (electric shock to restore normal rhythm) or radiofrequency ablation can be considered. Radiofrequency ablation is an invasive procedure performed in the hospital in the cardiac catheterization laboratory. During this procedure, x-rays are utilized to position a special catheter at the exact place in the heart where the abnormal rhythm is generated and “microwave-like” energy is transmitted to destroy this area and prevent the abnormal rhythm. Radiofrequency ablation is only performed by electrophysiologists who have special training in this procedure. Your physician can refer you to an electrophysiologist with this expertise if necessary.

In summary, atrial fibrillation is a common non life threatening rhythm disturbance of the heart. The approach for treatment varies with each patient. Whether it is rate control or restoration of normal rhythm, with any one of many modalities, the risks and benefits of medical and/or invasive treatment must be weighed carefully and discussed in detail with your physician.

Sources:

American Heart Association
Cleveland Clinic Journal of Medicine
Electrophysiology Division University of California San Francisco
Heart Rhythm Society
Medline Plus

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