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
