Atrial fibrillation may not be a common household term, but it describes the nation's most common type of cardiac arrhythmia, or abnormal heartbeat. In fact, atrial fibrillation affects more than 2 million people in the United States, and it increases the risk for stroke and heart failure. It's also an equal opportunity ailment, affecting women as well as men.

Causes, Symptoms And Risks

The culprit in atrial fibrillation is malfunction of the atria, the two upper chambers of the heart. Normally, the atria contract in a wondrous synchrony that facilitates blood flow from the upper chambers to the lower ones, called the ventricles, explains Shaun Cho, M.D., an electrophysiologist (cardiologist with advanced training in the diagnosis and treatment of arrhythmias) at the John Muir Cardiac Rhythm Center. "During atrial fibrillation, there's a chaotic quivering of the upper chambers, and that leads to inefficient blood flow and pooling in the upper chambers," says Dr. Cho. "Pools of blood tend to form clots, which can sometimes be sent from the heart out to the blood vessels. If the clot goes to the brain, it can cause a stroke." In fact, he adds, 15 percent of strokes can be traced to atrial fibrillation.

Beyond stroke, atrial fibrillation can lead to other health problems, including heart failure. "Typically, these patients lose 15 to 20 percent of cardiac output," says Paul Ludmer, M.D., an electrophysiologist on staff at the John Muir Cardiac Rhythm Center.

In about half of atrial fibrillation cases, patients experience rapid, irregular heartbeat or palpitations, fatigue and shortness of breath. In the other half of cases, patients don't notice any symptoms.

Fortunately, medical science has pinpointed risk factors for atrial fibrillation. Increasing age plays a role. According to Dr. Cho, as many as two to three percent of those over 60 and 10 percent of those over 80 have the condition. Other risk factors include high blood pressure, coronary artery disease, diabetes, overactive thyroid and excessive alcohol consumption.

Diagnosis And Treatments

Atrial fibrillation's quivering heartbeat clearly audible with a stethoscope—is typically discovered by a doctor during a physical exam. Once a follow-up ECG (electrocardiogram) confirms the diagnosis, explains Dr. Cho, "we look for reversible factors, such as hypertension and hyperthyroidism, and address those issues." At the same time, high-risk patients are started on an anticoagulant medication, such as Coumadin, to prevent blood clots and reduce the risk of stroke.

"Most people are also given some sort of drug to slow down a rapid heart rate," adds Dr. Ludmer. "The third line of treatment is to use specific drugs to restore normal heart rhythm."

If these strategies don't remedy the problem, some patients need a pacemaker to regulate their heartbeat. Others undergo a procedure called electrical cardioversion (sometimes done in combination with drug therapy), in which electrical shock is applied to the heart to jolt it into normal rhythm.

New Frontiers

An advanced procedure called ablation offers new hope for patients who are highly symptomatic and haven't been helped by standard therapies. "Ablation is definitely leading-edge," says Dr. Ludmer. "It uses radio frequency to destroy the abnormal cells that are triggering fibrillation. The procedure requires a great deal of advanced technology. We're fortunate to have this technology at John Muir's Cardiac Rhythm Center."

In ablation, catheters are guided through a vein in the patient's leg up to the heart. Special computerized mapping systems "allow us to see the upper chambers of the heart in 3-D and help us identify areas that need to be ablated," says Dr. Ludmer.

The volume of ablation procedures in a center is an important consideration, according to Dr. Cho. "A high-volume center is an advantage for patients," he says. "It attracts highly skilled physicians who want to be practicing at the cutting-edge of electrophysiology. For, physicians, we have the opportunity to work with people who have great expertise, which is ultimately reflected in our outcomes."

Dr. Ludmer is equally enthusiastic about the possibilities of the ablation procedure. "This intervention can allow patients to lead a normal life and be able to stop their medications for an amount of time and may well decrease the incidence of stroke and heart failure," he says. "I'm extremely excited that we have more and more tools to help our patients achieve a better lifestyle and enjoy a vast improvement of their symptoms and quality of life."